ngx_lua - Embed the power of Lua into Nginx
This module is not distributed with the Nginx source. See the installation instructions.
This module is under active development and is production ready.
This document describes ngx_lua v0.5.0rc17 released on 6 March 2012.
# set search paths for pure Lua external libraries (';;' is the default path):
lua_package_path '/foo/bar/?.lua;/blah/?.lua;;';
# set search paths for Lua external libraries written in C (can also use ';;'):
lua_package_cpath '/bar/baz/?.so;/blah/blah/?.so;;';
server {
location /inline_concat {
# MIME type determined by default_type:
default_type 'text/plain';
set $a "hello";
set $b "world";
# inline lua script
set_by_lua $res "return ngx.arg[1]..ngx.arg[2]" $a $b;
echo $res;
}
location /rel_file_concat {
set $a "foo";
set $b "bar";
# script path relative to nginx prefix
# $ngx_prefix/conf/concat.lua contents:
#
# return ngx.arg[1]..ngx.arg[2]
#
set_by_lua_file $res conf/concat.lua $a $b;
echo $res;
}
location /abs_file_concat {
set $a "fee";
set $b "baz";
# absolute script path not modified
set_by_lua_file $res /usr/nginx/conf/concat.lua $a $b;
echo $res;
}
location /lua_content {
# MIME type determined by default_type:
default_type 'text/plain';
content_by_lua "ngx.say('Hello,world!')";
}
location /nginx_var {
# MIME type determined by default_type:
default_type 'text/plain';
# try access /nginx_var?a=hello,world
content_by_lua "ngx.print(ngx.var['arg_a'], '\\n')";
}
location /request_body {
# force reading request body (default off)
lua_need_request_body on;
client_max_body_size 50k;
client_body_buffer_size 50k;
content_by_lua 'ngx.print(ngx.var.request_body)';
}
# transparent non-blocking I/O in Lua via subrequests
location /lua {
# MIME type determined by default_type:
default_type 'text/plain';
content_by_lua '
local res = ngx.location.capture("/some_other_location")
if res.status == 200 then
ngx.print(res.body)
end';
}
# GET /recur?num=5
location /recur {
# MIME type determined by default_type:
default_type 'text/plain';
content_by_lua '
local num = tonumber(ngx.var.arg_num) or 0
if num > 50 then
ngx.say("num too big")
return
end
ngx.say("num is: ", num)
if num > 0 then
res = ngx.location.capture("/recur?num=" .. tostring(num - 1))
ngx.print("status=", res.status, " ")
ngx.print("body=", res.body)
else
ngx.say("end")
end
';
}
location /foo {
rewrite_by_lua '
res = ngx.location.capture("/memc",
{ args = { cmd = 'incr', key = ngx.var.uri } }
)
';
proxy_pass http://blah.blah.com;
}
location /blah {
access_by_lua '
local res = ngx.location.capture("/auth")
if res.status == ngx.HTTP_OK then
return
end
if res.status == ngx.HTTP_FORBIDDEN then
ngx.exit(res.status)
end
ngx.exit(ngx.HTTP_INTERNAL_SERVER_ERROR)
';
# proxy_pass/fastcgi_pass/postgres_pass/...
}
location /mixed {
rewrite_by_lua_file /path/to/rewrite.lua;
access_by_lua_file /path/to/access.lua;
content_by_lua_file /path/to/content.lua;
}
# use nginx var in code path
# WARN: contents in nginx var must be carefully filtered,
# otherwise there'll be great security risk!
location ~ ^/app/(.+) {
content_by_lua_file /path/to/lua/app/root/$1.lua;
}
location / {
lua_need_request_body on;
client_max_body_size 100k;
client_body_buffer_size 100k;
access_by_lua '
-- check the client IP addr is in our black list
if ngx.var.remote_addr == "132.5.72.3" then
ngx.exit(ngx.HTTP_FORBIDDEN)
end
-- check if the request body contains bad words
if ngx.var.request_body and
string.match(ngx.var.request_body, "fsck")
then
return ngx.redirect("/terms_of_use.html")
end
-- tests passed
';
# proxy_pass/fastcgi_pass/etc settings
}
}
This module embeds Lua, via the standard interpreter or LuaJIT, into Nginx and by leveraging Nginx subrequests, allows the integration of the powerful Lua threads ( Lua coroutines) into the Nginx event model.
Unlike Apache's mod_lua and Lighttpd's mod_magnet, Lua code executed using this module can be 100% non-blocking on network traffic as long as either of the ngx.location.capture or ngx.location.capture_multi interfaces are used to handle requests to upstream services such as mysql, postgresql, memcached, redis, or upstream http web services. (see HttpDrizzleModule, ngx_postgres, HttpMemcModule, HttpRedis2Module and HttpProxyModule modules for details).
The Lua interpreter or LuaJIT instance is shared across all the requests in a single nginx worker process but request contexts are segregated using lightweight Lua coroutines. Loaded Lua modules persist at the nginx worker process level resulting in a small memory footprint even when under heavy loads.
syntax: lua_code_cache on | off
default: lua_code_cache on
context: main, server, location, location if
Enables or disables the Lua code cache for set_by_lua_file, content_by_lua_file, rewrite_by_lua_file, and access_by_lua_file, and also force Lua module reloading on a per-request basis.
The Lua files referenced in set_by_lua_file,
content_by_lua_file, access_by_lua_file,
and rewrite_by_lua_file will not be cached
and the Lua package.loaded table will be cleared
at the entry point of every request (such that Lua modules
will not be cached either). With this in place, developers can adopt an edit and refresh approach.
Please note however, that Lua code inlined into nginx.conf
such as those specified by set_by_lua, content_by_lua,
access_by_lua, and rewrite_by_lua will always be
cached because only the Nginx config file parser can correctly parse the nginx.conf
file and the only ways to to reload the config file
are to send a HUP signal or to restart Nginx.
The ngx_lua module does not currently support the stat mode available with the
Apache mod_lua module but this is planned for implementation in the future.
Disabling the Lua code cache is strongly discouraged for production use and should only be used during development as it has a significant negative impact on overall performance. In addition, race conditions when reloading Lua modules are common for concurrent requests when the code cache is disabled.
syntax: lua_regex_cache_max_entries <num>
default: lua_regex_cache_max_entries 1024
context: http
Specifies the maximum number of entries allowed in the worker process level compiled regex cache.
The regular expressions used in ngx.re.match, ngx.re.gmatch, ngx.re.sub, and ngx.re.gsub will be cached within this cache if the regex option o (i.e., compile-once flag) is specified.
The default number of entries allowed is 1024 and when this limit is reached, new regexes will not be cached (as if the o option was not specified) and there will be one, and only one, warning in the error.log file:
2011/08/27 23:18:26 [warn] 31997#0: *1 lua exceeding regex cache max entries (1024), ...
Do not activate the o option for regexes (and/or replace string arguments for ngx.re.sub and ngx.re.gsub) that are generated on the fly and give rise to infinite variations to avoid hitting the specified limit.
syntax: lua_package_path <lua-style-path-str>
default: The content of LUA_PATH environ variable or Lua's compiled-in defaults.
context: main
Sets the Lua module search path used by scripts specified by set_by_lua,
content_by_lua and others. The path string is in standard Lua path form, and ;;
can be used to stand for the original path.
syntax: lua_package_cpath <lua-style-cpath-str>
default: The content of LUA_CPATH environ variable or Lua's compiled-in defaults.
context: main
Sets the Lua C-module search path used by scripts specified by set_by_lua,
content_by_lua and others. The cpath string is in standard Lua cpath form, and ;;
can be used to stand for the original cpath.
syntax: set_by_lua $res <lua-script-str> [$arg1 $arg2 ...]
context: main, server, location, server if, location if
phase: rewrite
Executes code specified in <lua-script-str> with optional input arguments $arg1 $arg2 ..., and returns string output to $res.
The code in <lua-script-str> can make API calls and can retrieve input arguments from the ngx.arg table (index starts from 1 and increases sequentially).
This directive is designed to execute short, fast running code blocks as the Nginx event loop is blocked during code execution. Time consuming code sequences should therefore be avoided.
Note that I/O operations such as ngx.say, ngx.exec, echo and similar are not permitted within the context of this directive.
In addition, note that this directive can only output a value to a single Nginx variable at a time. However, a workaround is possible using the ngx.var.VARIABLE interface.
location /foo {
set $diff ''; # we have to predefine the $diff variable here
set_by_lua $sum '
local a = 32
local b = 56
ngx.var.diff = a - b; -- write to $diff directly
return a + b; -- return the $sum value normally
';
echo "sum = $sum, diff = $diff";
}
This directive can be freely mixed with all directives of the HttpRewriteModule, HttpSetMiscModule, and HttpArrayVarModule modules. All of these directives will run in the same order as they appear in the config file.
set $foo 32;
set_by_lua $bar 'tonumber(ngx.var.foo) + 1';
set $baz "bar: $bar"; # $baz == "bar: 33"
This directive requires the ngx_devel_kit module.
syntax: set_by_lua_file $res <path-to-lua-script-file> [$arg1 $arg2 ...]
context: main, server, location, server if, location if
phase: rewrite
Equivalent to set_by_lua, except that the file specified by <path-to-lua-script-file> contains the lua code to be executed.
When the Lua code cache is on (default state), the user code is loaded once at the first request and cached
and the Nginx config must be reloaded each time the Lua source file is modified.
The Lua code cache can be temporarily disabled during development by
switching lua_code_cache off in nginx.conf to avoid reloading Nginx.
This directive requires the ngx_devel_kit module.
syntax: content_by_lua <lua-script-str>
context: location, location if
phase: content
Acts as a "content handler" and executes lua code string specified in <lua-script-str> for every request.
The lua code may make API calls and is executed as a new spawned coroutine in an independent global environment (i.e. a sandbox).
Do not use this directive and other content handler directives in the same location. For example, this directive and the proxy_pass directive should not be used in the same location.
syntax: content_by_lua_file <path-to-lua-script-file>
context: location, location if
phase: content
Equivalent to content_by_lua, except that the file specified by <path-to-lua-script-file> contains the lua code to be executed.
Nginx variables can be used in the <path-to-lua-script-file> string to provide flexibility. This however carries some risks and is not ordinarily recommended.
When the Lua code cache is on (default state), the user code is loaded once at the first request and cached
and the Nginx config must be reloaded each time the Lua source file is modified.
The Lua code cache can be temporarily disabled during development by
switching lua_code_cache off in nginx.conf to avoid reloading Nginx.
syntax: rewrite_by_lua <lua-script-str>
context: http, server, location, location if
phase: rewrite tail
Acts as a rewrite phase handler and executes Lua code string specified in <lua-script-str> for every request.
The Lua code may make API calls and is executed as a new spawned coroutine in an independent global environment (i.e. a sandbox).
Note that this handler always runs after the standard HttpRewriteModule. So the following will work as expected:
location /foo {
set $a 12; # create and initialize $a
set $b ""; # create and initialize $b
rewrite_by_lua 'ngx.var.b = tonumber(ngx.var.a) + 1';
echo "res = $b";
}
because set $a 12 and set $b "" run before rewrite_by_lua.
On the other hand, the following will not work as expected:
? location /foo {
? set $a 12; # create and initialize $a
? set $b ''; # create and initialize $b
? rewrite_by_lua 'ngx.var.b = tonumber(ngx.var.a) + 1';
? if ($b = '13') {
? rewrite ^ /bar redirect;
? break;
? }
?
? echo "res = $b";
? }
because if runs before rewrite_by_lua even if it is put after rewrite_by_lua in the config.
The right way of doing this is as follows:
location /foo {
set $a 12; # create and initialize $a
set $b ''; # create and initialize $b
rewrite_by_lua '
ngx.var.b = tonumber(ngx.var.a) + 1
if tonumber(ngx.var.b) == 13 then
return ngx.redirect("/bar");
end
';
echo "res = $b";
}
Note that the ngx_eval module can be approximated using rewrite_by_lua. For example,
location / {
eval $res {
proxy_pass http://foo.com/check-spam;
}
if ($res = 'spam') {
rewrite ^ /terms-of-use.html redirect;
}
fastcgi_pass ...;
}
can be implemented in ngx_lua as:
location = /check-spam {
internal;
proxy_pass http://foo.com/check-spam;
}
location / {
rewrite_by_lua '
local res = ngx.location.capture("/check-spam")
if res.body == "spam" then
ngx.redirect("/terms-of-use.html")
end
';
fastcgi_pass ...;
}
Just as any other rewrite phase handlers, rewrite_by_lua also runs in subrequests.
Note that when calling ngx.exit(ngx.OK) within a rewrite_by_lua handler, the nginx request processing control flow will still continue to the content handler. To terminate the current request from within a rewrite_by_lua handler, calling ngx.exit with status >= 200 (ngx.HTTP_OK) and status < 300 (ngx.HTTP_SPECIAL_RESPONSE) for successful quits and ngx.exit(ngx.HTTP_INTERNAL_SERVER_ERROR) (or its friends) for failures.
If the HttpRewriteModule's rewrite directive is used to change the URI and initiate location re-lookups (internal redirections), then any rewrite_by_lua or rewrite_by_lua_file code sequences within the current location will not be executed. For example,
location /foo {
rewrite ^ /bar;
rewrite_by_lua 'ngx.exit(503)';
}
location /bar {
...
}
Here the Lua code ngx.exit(503) will never run. This will be the case if rewrite ^ /bar last is used as this will similarly initiate an internal redirection. If the break modifier is used instead, there will be no internal rediction and the rewrite_by_lua code will be executed.
syntax: rewrite_by_lua_file <path-to-lua-script-file>
context: http, server, location, location if
phase: rewrite tail
Equivalent to rewrite_by_lua, except that the file specified by <path-to-lua-script-file> contains the Lua code to be executed.
Nginx variables can be used in the <path-to-lua-script-file> string to provide flexibility. This however carries some risks and is not ordinarily recommended.
When the Lua code cache is on (default state), the user code is loaded once at the first request and cached and the Nginx config must be reloaded each time the Lua source file is modified. The Lua code cache can be temporarily disabled during development by switching lua_code_cache off in nginx.conf to avoid reloading Nginx.
syntax: access_by_lua <lua-script-str>
context: http, server, location, location if
phase: access tail
Acts as an access phase handler and executes lua code string specified in <lua-script-str> for every request.
The Lua code may make API calls and is executed as a new spawned coroutine in an independent global environment (i.e. a sandbox).
Note that this handler always runs after the standard HttpAccessModule. So the following will work as expected:
location / {
deny 192.168.1.1;
allow 192.168.1.0/24;
allow 10.1.1.0/16;
deny all;
access_by_lua '
local res = ngx.location.capture("/mysql", { ... })
...
';
# proxy_pass/fastcgi_pass/...
}
That is, if a client IP address is in the blacklist, it will be denied before the MySQL query for more complex authentication is executed by access_by_lua.
Note that the ngx_auth_request module can be approximated using access_by_lua:
location / {
auth_request /auth;
# proxy_pass/fastcgi_pass/postgres_pass/...
}
can be implemented in ngx_lua as:
location / {
access_by_lua '
local res = ngx.location.capture("/auth")
if res.status == ngx.HTTP_OK then
return
end
if res.status == ngx.HTTP_FORBIDDEN then
ngx.exit(res.status)
end
ngx.exit(ngx.HTTP_INTERNAL_SERVER_ERROR)
';
# proxy_pass/fastcgi_pass/postgres_pass/...
}
As with other access phase handlers, access_by_lua will not run in subrequests.
Note that when calling ngx.exit(ngx.OK) within a access_by_lua handler, the nginx request processing control flow will still continue to the content handler. To terminate the current request from within a access_by_lua handler, calling ngx.exit with status >= 200 (ngx.HTTP_OK) and status < 300 (ngx.HTTP_SPECIAL_RESPONSE) for successful quits and ngx.exit(ngx.HTTP_INTERNAL_SERVER_ERROR) (or its friends) for failures.
syntax: access_by_lua_file <path-to-lua-script-file>
context: http, server, location, location if
phase: access tail
Equivalent to access_by_lua, except that the file specified by <path-to-lua-script-file> contains the Lua code to be executed.
Nginx variables can be used in the <path-to-lua-script-file> string to provide flexibility. This however carries some risks and is not ordinarily recommended.
When the Lua code cache is on (default state), the user code is loaded once at the first request and cached
and the Nginx config must be reloaded each time the Lua source file is modified.
The Lua code cache can be temporarily disabled during development by switching lua_code_cache off in nginx.conf to avoid repeatedly reloading Nginx.
syntax: header_filter_by_lua <lua-script-str>
context: http, server, location, location if
phase: output-header-filter
Uses Lua code specified in <lua-script-str> to define an output header filter. Note that the following API functions are currently disabled within this context:
- Output API functions (e.g., ngx.say and ngx.send_headers)
- Control API functions (e.g., ngx.exit)
- Subrequest API functions (e.g., ngx.location.capture and ngx.location.capture_multi)
Here is an example of overriding a response header (or adding one if absent) in our Lua header filter:
location / {
proxy_pass http://mybackend;
header_filter_by_lua 'ngx.header.Foo = "blah"';
}
This directive was first introduced in the v0.2.1rc20 release.
syntax: header_filter_by_lua_file <path-to-lua-script-file>
context: http, server, location, location if
phase: output-header-filter
Equivalent to header_filter_by_lua, except that the file specified by <path-to-lua-script-file> contains the lua code to be executed.
This directive was first introduced in the v0.2.1rc20 release.
syntax: lua_need_request_body <on|off>
default: off
context: main | server | location
phase: depends on usage
Determines whether to force the request body data to be read before running rewrite/access/access_by_lua* or not. The Nginx core does not read the client request body by default and if request body data is required, then this directive should be turned on or the ngx.req.read_body function should be called within the Lua code.
To read the request body data within the $request_body variable, client_body_buffer_size must have the same value as client_max_body_size. Because when the content length exceeds client_body_buffer_size but less than client_max_body_size, Nginx will automatically buffer the data into a temporary file on the disk, which will lead to empty value in the $request_body variable.
If the current location includes rewrite_by_lua or rewrite_by_lua_file directives,
then the request body will be read just before the rewrite_by_lua or rewrite_by_lua_file code is run (and also at the
rewrite phase). Similarly, if only content_by_lua is specified,
the request body will not be read until the content handler's Lua code is
about to run (i.e., the request body will be read during the content phase).
It is recommended however, to use the ngx.req.read_body and ngx.req.discard_body functions for finer control over the request body reading process instead.
This also applies to access_by_lua and access_by_lua_file.
syntax: lua_shared_dict <name> <size>
default: no
context: http
phase: depends on usage
Declares a shared memory zone, <name>, to serve as storage for the shm-based Lua dictionary ngx.shared.<name>.
The <size> argument accepts size units such as k and m:
http {
lua_shared_dict dogs 10m;
...
}
See ngx.shared.DICT for details.
This directive was first introduced in the v0.3.1rc22 release.
syntax: lua_socket_connect_timeout <time>
default: lua_socket_connect_timeout 60s
context: http, server, location
This directive controls the default timeout value used in TCP/unix-domain socket object's connect method and can be overridden by the settimeout method.
The <time> argument can be an integer, with an optional time unit, like s (second), ms (millisecond), m (minute). The default time unit is s, i.e., "second". The default setting is 60s.
This directive was first introduced in the v0.5.0rc1 release.
syntax: lua_socket_send_timeout <time>
default: lua_socket_send_timeout 60s
context: http, server, location
Controls the default timeout value used in TCP/unix-domain socket object's send method and can be overridden by the settimeout method.
The <time> argument can be an integer, with an optional time unit, like s (second), ms (millisecond), m (minute). The default time unit is s, i.e., "second". The default setting is 60s.
This directive was first introduced in the v0.5.0rc1 release.
syntax: lua_socket_send_lowat <size>
default: lua_socket_send_lowat 0
context: http, server, location
Controls the lowat (low water) value for the cosocket send buffer.
syntax: lua_socket_read_timeout <time>
default: lua_socket_read_timeout 60s
context: http, server, location
phase: depends on usage
This directive controls the default timeout value used in TCP/unix-domain socket object's receive method and iterator functions returned by the receiveuntil method. This setting can be overridden by the settimeout method.
The <time> argument can be an integer, with an optional time unit, like s (second), ms (millisecond), m (minute). The default time unit is s, i.e., "second". The default setting is 60s.
This directive was first introduced in the v0.5.0rc1 release.
syntax: lua_socket_buffer_size <size>
default: lua_socket_buffer_size 4k/8k
context: http, server, location
Specifies the buffer size used by cosocket reading operations.
This buffer does not have to be that big to hold everything at the same time because cosocket supports 100% non-buffered reading and parsing. So even 1 byte buffer size should still work everywhere but the performance could be bad.
This directive was first introduced in the v0.5.0rc1 release.
syntax: lua_socket_pool_size <size>
default: lua_socket_pool_size 30
context: http, server, location
Specifies the size limit (in terms of connection count) for every cosocket connection pool associated with every remote server (i.e., identified by either the host-port pair or the unix domain socket file path).
Default to 30 connections for every pool.
When the connection pool is exceeding the size limit, the least recently used (idle) connection already in the pool will be closed automatically to make room for the current connection.
Note that the cosocket connection pool is per nginx worker process rather than per nginx server instance, so so size limit specified here also applies to every single nginx worker process.
This directive was first introduced in the v0.5.0rc1 release.
syntax: lua_socket_keepalive_timeout <time>
default: lua_socket_keepalive_timeout 60s
context: http, server, location
This directive controls the default maximal idle time of the connections in the cosocket built-in connection pool. When this timeout reaches, idle connections will be closed automatically and removed from the pool. This setting can be overridden by cosocket objects' setkeepalive method.
The <time> argument can be an integer, with an optional time unit, like s (second), ms (millisecond), m (minute). The default time unit is s, ie, "second". The default setting is 60s.
This directive was first introduced in the v0.5.0rc1 release.
The various *_by_lua and *_by_lua_file configuration directives serve as gateways to the Lua API within the nginx.conf file. The Nginx Lua API described below can only be called within the user Lua code run in the context of these configuration directives.
The API is exposed to Lua in the form of two standard packages ngx and ndk. These packages are in the default global scope within ngx_lua and are always available within ngx_lua directives.
The packages can be introduced into external Lua modules by using the package.seeall option:
module("my_module", package.seeall)
function say(a) ngx.say(a) end
Alternatively, they can be imported to external Lua modules by using file scoped local Lua variables:
local ngx = ngx
module("my_module")
function say(a) ngx.say(a) end
It is also possible to directly require the packages in external Lua modules:
local ngx = require "ngx"
local ndk = require "ndk"
The ability to require these packages was introduced in the v0.2.1rc19 release.
Network I/O operations in user code should only be done through the Nginx Lua API calls as the Nginx event loop may be blocked and performance drop off dramatically otherwise. Disk operations with relatively small amount of data can be done using the standard Lua io library but huge file reading and writing should be avoided wherever possible as they may block the Nginx process significantly. Delegating all network and disk I/O operations to Nginx subrequests (via the ngx.location.capture method and similar) is strongly recommended for maximum performance.
syntax: val = ngx.arg[index]
context: set_by_lua*
Index the input arguments to the set_by_lua and set_by_lua_file directives:
value = ngx.arg[n]
Here is an example
location /foo {
set $a 32;
set $b 56;
set_by_lua $res
'return tonumber(ngx.arg[1]) + tonumber(ngx.arg[2])'
$a $b;
echo $sum;
}
that outputs 88, the sum of 32 and 56.
syntax: ngx.var.VAR_NAME
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Read and write Nginx variable values.
value = ngx.var.some_nginx_variable_name
ngx.var.some_nginx_variable_name = value
Note that only already defined nginx variables can be written to. For example:
location /foo {
set $my_var ''; # this line is required to create $my_var at config time
content_by_lua '
ngx.var.my_var = 123;
...
';
}
That is, nginx variables cannot be created on-the-fly.
Some special nginx variables like $args and $limit_rate can be assigned a value,
some are not, like $arg_PARAMETER.
Nginx regex group capturing variables $1, $2, $3, and etc, can be read by this
interface as well, by writing ngx.var[1], ngx.var[2], ngx.var[3], and etc.
Setting ngx.var.Foo to a nil value will unset the $Foo Nginx variable.
ngx.var.args = nil
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
ngx.OK (0)
ngx.ERROR (-1)
ngx.AGAIN (-2)
ngx.DONE (-4)
Note that only two of these constants are utilized by the Nginx API for Lua (i.e., ngx.exit accepts NGX_OK and NGX_ERROR as input).
ngx.null
The ngx.null constant is a NULL light userdata which is usually used to represent nil values in Lua tables and etc. It is identical with the lua-cjson library's cjson.null constant. This constant was first introduced in the v0.5.0rc5 release.
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
ngx.HTTP_GET
ngx.HTTP_HEAD
ngx.HTTP_PUT
ngx.HTTP_POST
ngx.HTTP_DELETE
These constants are usually used in ngx.location.catpure and ngx.location.capture_multi method calls.
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
value = ngx.HTTP_OK (200)
value = ngx.HTTP_CREATED (201)
value = ngx.HTTP_SPECIAL_RESPONSE (300)
value = ngx.HTTP_MOVED_PERMANENTLY (301)
value = ngx.HTTP_MOVED_TEMPORARILY (302)
value = ngx.HTTP_SEE_OTHER (303)
value = ngx.HTTP_NOT_MODIFIED (304)
value = ngx.HTTP_BAD_REQUEST (400)
value = ngx.HTTP_UNAUTHORIZED (401)
value = ngx.HTTP_FORBIDDEN (403)
value = ngx.HTTP_NOT_FOUND (404)
value = ngx.HTTP_NOT_ALLOWED (405)
value = ngx.HTTP_GONE (410)
value = ngx.HTTP_INTERNAL_SERVER_ERROR (500)
value = ngx.HTTP_METHOD_NOT_IMPLEMENTED (501)
value = ngx.HTTP_SERVICE_UNAVAILABLE (503)
value = ngx.HTTP_GATEWAY_TIMEOUT (504) (first added in the v0.3.1rc38 release)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
ngx.STDERR
ngx.EMERG
ngx.ALERT
ngx.CRIT
ngx.ERR
ngx.WARN
ngx.NOTICE
ngx.INFO
ngx.DEBUG
These constants are usually used by the ngx.log method.
syntax: print(...)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Writes ngx.NOTICE log level arguments prefixed with lua print: to the nginx error.log file.
It is equivalent to
ngx.log(ngx.NOTICE, 'lua print: ', a, b, ...)
Lua nil arguments are accepted and result in literal "nil" strings while Lua booleans result in literal "true" or "false" strings. And the ngx.null constant will yield the "null" string output.
There is a hard-coded length limitation on the error messages in the Nginx core. It is 2048 bytes at most, including the trailing newlines and the leading timestamps. You can manually modify this limit by modifying the NGX_MAX_ERROR_STR macro definition in the src/core/ngx_log.h file in the Nginx source tree. If the message size exceeds this limit, the Nginx core will truncate the message text automatically.
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
This table can be used to store per-request Lua context data and has a life time identical to the current request (as with the Nginx variables).
Consider the following example,
location /test {
rewrite_by_lua '
ngx.say("foo = ", ngx.ctx.foo)
ngx.ctx.foo = 76
';
access_by_lua '
ngx.ctx.foo = ngx.ctx.foo + 3
';
content_by_lua '
ngx.say(ngx.ctx.foo)
';
}
Then GET /test will yield the output
foo = nil
79
That is, the ngx.ctx.foo entry persists across the rewrite, access, and content phases of a request.
Every request, including subrequests, has its own copy of the table. For example:
location /sub {
content_by_lua '
ngx.say("sub pre: ", ngx.ctx.blah)
ngx.ctx.blah = 32
ngx.say("sub post: ", ngx.ctx.blah)
';
}
location /main {
content_by_lua '
ngx.ctx.blah = 73
ngx.say("main pre: ", ngx.ctx.blah)
local res = ngx.location.capture("/sub")
ngx.print(res.body)
ngx.say("main post: ", ngx.ctx.blah)
';
}
Then GET /main will give the output
main pre: 73
sub pre: nil
sub post: 32
main post: 73
Here, modification of the ngx.ctx.blah entry in the subrequest does not affect the one in the parent request. This is because they have two separate versions of ngx.ctx.blah.
Internal redirection will destroy the original request ngx.ctx data (if any) and the new request will have an empty ngx.ctx table. For instance,
location /new {
content_by_lua '
ngx.say(ngx.ctx.foo)
';
}
location /orig {
content_by_lua '
ngx.ctx.foo = "hello"
ngx.exec("/new")
';
}
Then GET /orig will give
nil
rather than the original "hello" value.
Arbitrary data values, including Lua closures and nested tables, can be inserted into this "matic" table. It also allows the registration of custom meta methods.
Overriding ngx.ctx with a new Lua table is also supported, for example,
ngx.ctx = { foo = 32, bar = 54 }
syntax: res = ngx.location.capture(uri, options?)
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Issue a synchronous but still non-blocking Nginx Subrequest using uri.
Nginx subrequests provide a powerful way to make non-blocking internal requests to other locations configured with disk file directory or any other nginx C modules like ngx_proxy, ngx_fastcgi, ngx_memc,
ngx_postgres, ngx_drizzle, and even ngx_lua itself and etc etc etc.
Also note that subrequests just mimic the HTTP interface but there is no extra HTTP/TCP traffic nor IPC involved. Everything works internally, efficiently, on the C level.
Subrequests are completely different from HTTP 301/302 redirection (via ngx.redirect) and internal redirection (via ngx.exec).
Here is a basic example:
res = ngx.location.capture(uri)
Returns a Lua table with three slots (res.status, res.header, and res.body).
res.header holds all the response headers of the
subrequest and it is a normal Lua table. For multi-value response headers,
the value is a Lua (array) table that holds all the values in the order that
they appear. For instance, if the subrequest response headers contains the following
lines:
Set-Cookie: a=3
Set-Cookie: foo=bar
Set-Cookie: baz=blah
Then res.header["Set-Cookie"] will be evaluted to the table value
{"a=3", "foo=bar", "baz=blah"}.
URI query strings can be concatenated to URI itself, for instance,
res = ngx.location.capture('/foo/bar?a=3&b=4')
Named locations like @foo are not allowed due to a limitation in
the nginx core. Use normal locations combined with the internal directive to
prepare internal-only locations.
An optional option table can be fed as the second argument, which support the options:
methodspecify the subrequest's request method, which only accepts constants likengx.HTTP_POST.bodyspecify the subrequest's request body (string value only).argsspecify the subrequest's URI query arguments (both string value and Lua tables are accepted)ctxspecify a Lua table to be the ngx.ctx table for the subrequest. It can be the current request's ngx.ctx table, which effectively make the parent and its subrequest to share exactly the same context table. This option was first introduced in thev0.3.1rc25release.varstake a Lua table which holds the values to set the specified Nginx variables in the subrequest as this option's value. This option was first introduced in thev0.3.1rc31release.copy_all_varsspecify whether to copy over all the Nginx variable values of the current request to the subrequest in question. modifications of the nginx variables in the subrequest will not affect the current (parent) request. This option was first introduced in thev0.3.1rc31release.share_all_varsspecify whether to share all the Nginx variables of the subrequest with the current (parent) request. modifications of the Nginx variables in the subrequest will affect the current (parent) request.
Issuing a POST subrequest, for example, can be done as follows
res = ngx.location.capture(
'/foo/bar',
{ method = ngx.HTTP_POST, body = 'hello, world' }
)
See HTTP method constants methods other than POST.
The method option is ngx.HTTP_GET by default.
The args option can specify extra URI arguments, for instance,
ngx.location.capture('/foo?a=1',
{ args = { b = 3, c = ':' } }
)
is equivalent to
ngx.location.capture('/foo?a=1&b=3&c=%3a')
that is, this method will automatically escape argument keys and values according to URI rules and
concatenating them together into a complete query string. The format for the Lua table passed as the args argument is identical to the format used in the ngx.encode_args method.
The args option can also take plain query strings:
ngx.location.capture('/foo?a=1',
{ args = 'b=3&c=%3a' } }
)
This is functionally identical to the previous examples.
The share_all_vars option controls whether to share nginx variables among the current request and new subrequests.
If this option is set to true, then the current request and associated subrequests will share the same Nginx variable scope. Hence, changes to Nginx variables made by a subrequest will affect the current request.
Care should be taken in using this option as variable scope sharing can have unexpected side effects. The args, vars, or copy_all_vars options are generally preferable instead.
This option is set to false by default
location /other {
set $dog "$dog world";
echo "$uri dog: $dog";
}
location /lua {
set $dog 'hello';
content_by_lua '
res = ngx.location.capture("/other",
{ share_all_vars = true });
ngx.print(res.body)
ngx.say(ngx.var.uri, ": ", ngx.var.dog)
';
}
Accessing location /lua gives
/other dog: hello world
/lua: hello world
The copy_all_vars option provides a copy of the parent request's Nginx variables to subrequests when such subrequests are issued. Changes made to these variables by such subrequests will not affect the parent request or any other subrequests sharing the parent request's variables.
location /other {
set $dog "$dog world";
echo "$uri dog: $dog";
}
location /lua {
set $dog 'hello';
content_by_lua '
res = ngx.location.capture("/other",
{ copy_all_vars = true });
ngx.print(res.body)
ngx.say(ngx.var.uri, ": ", ngx.var.dog)
';
}
Request GET /lua will give the output
/other dog: hello world
/lua: hello
Note that if both share_all_vars and copy_all_vars are set to true, then share_all_vars takes precedence.
In addition to the two settings above, it is possible to specify
values for variables in the subrequest using the vars option. These
variables are set after the sharing or copying of variables has been
evaluated, and provides a more efficient method of passing specific
values to a subrequest over encoding them as URL arguments and
unescaping them in the Nginx config file.
location /other {
content_by_lua '
ngx.say("dog = ", ngx.var.dog)
ngx.say("cat = ", ngx.var.cat)
';
}
location /lua {
set $dog '';
set $cat '';
content_by_lua '
res = ngx.location.capture("/other",
{ vars = { dog = "hello", cat = 32 }});
ngx.print(res.body)
';
}
Accessing /lua will yield the output
dog = hello
cat = 32
The ctx option can be used to specify a custom Lua table to serve as the ngx.ctx table for the subrequest.
location /sub {
content_by_lua '
ngx.ctx.foo = "bar";
';
}
location /lua {
content_by_lua '
local ctx = {}
res = ngx.location.capture("/sub", { ctx = ctx })
ngx.say(ctx.foo);
ngx.say(ngx.ctx.foo);
';
}
Then request GET /lua gives
bar
nil
It is also possible to use this ctx option to share the same ngx.ctx table between the current (parent) request and the subrequest:
location /sub {
content_by_lua '
ngx.ctx.foo = "bar";
';
}
location /lua {
content_by_lua '
res = ngx.location.capture("/sub", { ctx = ngx.ctx })
ngx.say(ngx.ctx.foo);
';
}
Request GET /lua yields the output
bar
Note that subrequests issued by ngx.location.capture inherit all the
request headers of the current request by default and that this may have unexpected side effects on the
subrequest responses. For example, when using the standard ngx_proxy module to serve
subrequests, an "Accept-Encoding: gzip" header in the main request may result
in gzipped responses that cannot be handled properly in Lua code. Original request headers should be ignored by setting
proxy_pass_request_headers to off in subrequest locations.
There is a hard-coded upper limit on the number of concurrent subrequests every main request. In older versions of Nginx, the limit is 50, which is then increased to 200 in recent Nginx 1.1.x releases. You can manually edit this limit by modifying the definition of the NGX_HTTP_MAX_SUBREQUESTS macro in the nginx/src/http/ngx_http_request.h file in the Nginx source tree. When you are exceeding this limit, you will get the following error message in your error.log file:
[error] 13983#0: *1 subrequests cycle while processing "/uri"
Please also refer to restrictions on capturing locations that include Echo Module directives.
syntax: res1, res2, ... = ngx.location.capture_multi({ {uri, options?}, {uri, options?}, ... })
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Just like ngx.location.capture, but supports multiple subrequests running in parallel.
This function issues several parallel subrequests specified by the input table and returns their results in the same order. For example,
res1, res2, res3 = ngx.location.capture_multi{
{ "/foo", { args = "a=3&b=4" } },
{ "/bar" },
{ "/baz", { method = ngx.HTTP_POST, body = "hello" } },
}
if res1.status == ngx.HTTP_OK then
...
end
if res2.body == "BLAH" then
...
end
This function will not return until all the subrequests terminate. The total latency is the longest latency of the individual subrequests rather than the sum.
Lua tables can be used for both requests and responses when the number of subrequests to be issued is not known in advance:
-- construct the requests table
local reqs = {}
table.insert(reqs, { "/mysql" })
table.insert(reqs, { "/postgres" })
table.insert(reqs, { "/redis" })
table.insert(reqs, { "/memcached" })
-- issue all the requests at once and wait until they all return
local resps = { ngx.location.capture_multi(reqs) }
-- loop over the responses table
for i, resp in ipairs(resps) do
-- process the response table "resp"
end
The ngx.location.capture function is just a special form of this function. Logically speaking, the ngx.location.capture can be implemented like this
ngx.location.capture =
function (uri, args)
return ngx.location.capture_multi({ {uri, args} })
end
Please also refer to restrictions on capturing locations that include Echo Module directives.
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Read and write the current request's response status. This should be called before sending out the response headers.
ngx.status = ngx.HTTP_CREATED
status = ngx.status
syntax: ngx.header.HEADER = VALUE
syntax: value = ngx.header.HEADER
context: rewrite_by_lua, access_by_lua*, content_by_lua*, header_filter_by_lua**
Set, add to, or clear the current request HEADER response header. Underscores (_) in the header names will be replaced by dashes (-) and the header names will be matched case-insensitively.
-- equivalent to ngx.header["Content-Type"] = 'text/plain'
ngx.header.content_type = 'text/plain';
ngx.header["X-My-Header"] = 'blah blah';
Multi-value headers can be set this way:
ngx.header['Set-Cookie'] = {'a=32; path=/', 'b=4; path=/'}
will yield
Set-Cookie: a=32; path=/
Set-Cookie: b=4; path=/
in the response headers.
Only Lua tables are accepted (Only the last element in the table will take effect for standard headers such as Content-Type that only accept a single value).
ngx.header.content_type = {'a', 'b'}
is equivalent to
ngx.header.content_type = 'b'
Setting a slot to nil effectively removes it from the response headers:
ngx.header["X-My-Header"] = nil;
The same applies to assigning an empty table:
ngx.header["X-My-Header"] = {};
Setting ngx.header.HEADER after sending out response headers (either explicitly with ngx.send_headers or implicitly with ngx.print and similar) will throw out a Lua exception.
Reading ngx.header.HEADER will return the value of the response header named HEADER.
Underscores (_) in the header names will also be replaced by dashes (-) and the header names will be matched case-insensitively. If the response header is not present at all, nil will be returned.
This is particularly useful in the context of header_filter_by_lua and header_filter_by_lua_file, for example,
location /test {
set $footer '';
proxy_pass http://some-backend;
header_filter_by_lua '
if ngx.header["X-My-Header"] == "blah" then
ngx.var.footer = "some value"
end
';
echo_after_body $footer;
}
For multi-value headers, all of the values of header will be collected in order and returned as a Lua table. For example, response headers
Foo: bar
Foo: baz
will result in
{"bar", "baz"}
to be returned when reading ngx.header.Foo.
Note that ngx.header is not a normal Lua table and as such, it is not possible to iterate through it using the Lua ipairs function.
For reading request headers, use the ngx.req.get_headers function instead.
syntax: ngx.req.set_uri(uri, jump?)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Rewrite the current request's (parsed) URI by the uri argument. The uri argument must be a Lua string and cannot be of zero length, or a Lua exception will be thrown.
The optional boolean jump argument can trigger location rematch (or location jump) as HttpRewriteModule's rewrite directive, that is, when jump is true (default to false), this function will never return and it will tell Nginx to try re-searching locations with the new URI value at the later post-rewrite phase and jumping to the new location.
Location jump will not be triggered otherwise, and only the current request's URI will be modified, which is also the default behavior. This function will return but with no returned values when the jump argument is false or absent altogether.
For example, the following nginx config snippet
rewrite ^ /foo last;
can be coded in Lua like this:
ngx.req.set_uri("/foo", true)
Similarly, Nginx config
rewrite ^ /foo break;
can be coded in Lua as
ngx.req.set_uri("/foo", false)
or equivalently,
ngx.req.set_uri("/foo")
The jump can only be set to true in rewrite_by_lua and rewrite_by_lua_file. Use of jump in other contexts is prohibited and will throw out a Lua exception.
A more sophisticated example involving regex substitutions is as follows
location /test {
rewrite_by_lua '
local uri = ngx.re.sub(ngx.var.uri, "^/test/(.*)", "$1", "o")
ngx.req.set_uri(uri)
';
proxy_pass http://my_backend;
}
which is functionally equivalent to
location /test {
rewrite ^/test/(.*) /$1 break;
proxy_pass http://my_backend;
}
Note that it is not possible to use this interface to rewrite URI arguments and that ngx.req.set_uri_args should be used for this instead. For instance, Nginx config
rewrite ^ /foo?a=3? last;
can be coded as
ngx.req.set_uri_args("a=3")
ngx.req.set_uri("/foo", true)
or
ngx.req.set_uri_args({a = 3})
ngx.req.set_uri("/foo", true)
This interface was first introduced in the v0.3.1rc14 release.
syntax: ngx.req.set_uri_args(args)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Rewrite the current request's URI query arguments by the args argument. The args argument can be either a Lua string, as in
ngx.req.set_uri_args("a=3&b=hello%20world")
or a Lua table holding the query arguments' key-value pairs, as in
ngx.req.set_uri_args({ a = 3, b = "hello world" })
where in the latter case, this method will automatically escape argument keys and values according to the URI escaping rule.
This interface was first introduced in the v0.3.1rc13 release.
See also ngx.req.set_uri.
syntax: args = ngx.req.get_uri_args(count_limit?)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Returns a Lua table holding all the current request URL query arguments.
location = /test {
content_by_lua '
local args = ngx.req.get_uri_args()
for key, val in pairs(args) do
if type(val) == "table" then
ngx.say(key, ": ", table.concat(val, ", "))
else
ngx.say(key, ": ", val)
end
end
';
}
Then GET /test?foo=bar&bar=baz&bar=blah will yield the response body
foo: bar
bar: baz, blah
Multiple occurrences of an argument key will result in a table value holding all the values for that key in order.
Keys and values are automatically unescaped according to URI escaping rules. In the settings above, GET /test?a%20b=1%61+2 will yield:
a b: 1a 2
Arguments without the =<value> parts are treated as boolean arguments. GET /test?foo&bar will yield:
foo: true
bar: true
That is, they will take Lua boolean values true. However, they are different from arguments taking empty string values. GET /test?foo=&bar= will give something like
foo:
bar:
Empty key arguments are discarded. GET /test?=hello&=world will yield an empty output for instance.
Updating query arguments via the nginx variable $args (or ngx.var.args in Lua) at runtime is also supported:
ngx.var.args = "a=3&b=42"
local args = ngx.req.get_uri_args()
Here the args table will always look like
{a = 3, b = 42}
regardless of the actual request query string.
Note that a maximum of 100 request arguments are parsed by default (including those with the same name) and that additional request arguments are silently discarded to guard against potential denial of service attacks.
However, the optional count_limit function argument can be used to override this limit:
local args = ngx.req.get_uri_args(10)
This argument can be set to zero to remove the limit and to process all request arguments received:
local args = ngx.req.get_uri_args(0)
Removing the count_limit cap is strongly discouraged.
syntax: ngx.req.get_post_args(count_limit?)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Returns a Lua table holding all the current request POST query arguments (of the MIME type application/x-www-form-urlencoded). Call ngx.req.read_body to read the request body first or turn on the lua_need_request_body directive to avoid Lua exception errors.
location = /test {
content_by_lua '
ngx.req.read_body()
local args = ngx.req.get_post_args()
for key, val in pairs(args) do
if type(val) == "table" then
ngx.say(key, ": ", table.concat(val, ", "))
else
ngx.say(key, ": ", val)
end
end
';
}
Then
# Post request with the body 'foo=bar&bar=baz&bar=blah'
$ curl --data 'foo=bar&bar=baz&bar=blah' localhost/test
will yield the response body like
foo: bar
bar: baz, blah
Multiple occurrences of an argument key will result in a table value holding all of the values for that key in order.
Keys and values will be automatically unescaped according to URI escaping rules.
With the settings above,
# POST request with body 'a%20b=1%61+2'
$ curl -d 'a%20b=1%61+2' localhost/test
will yield:
a b: 1a 2
Arguments without the =<value> parts are treated as boolean arguments. GET /test?foo&bar will yield:
foo: true
bar: true
That is, they will take Lua boolean values true. However, they are different from arguments taking empty string values. POST /test with request body foo=&bar= will return something like
foo:
bar:
Empty key arguments are discarded. POST /test with body =hello&=world will yield empty outputs for instance.
Note that a maximum of 100 request arguments are parsed by default (including those with the same name) and that additional request arguments are silently discarded to guard against potential denial of service attacks.
However, the optional count_limit function argument can be used to override this limit:
local args = ngx.req.get_post_args(10)
This argument can be set to zero to remove the limit and to process all request arguments received:
local args = ngx.req.get_post_args(0)
Removing the count_limit cap is strongly discouraged.
syntax: headers = ngx.req.get_headers(count_limit?)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Returns a Lua table holding all the current request headers.
local h = ngx.req.get_headers()
for k, v in pairs(h) do
...
end
To read an individual header:
ngx.say("Host: ", ngx.req.get_headers()["Host"])
Note that the ngx.var.HEADER API call, which uses core $http_HEADER variables, may be more preferable for reading individual request headers.
For multiple instances of request headers such as:
Foo: foo
Foo: bar
Foo: baz
the value of ngx.req.get_headers()["Foo"] will be a Lua (array) table such as:
{"foo", "bar", "baz"}
Note that a maximum of 100 request headers are parsed by default (including those with the same name) and that additional request headers are silently discarded to guard against potential denial of service attacks.
However, the optional count_limit function argument can be used to override this limit:
local args = ngx.req.get_headers(10)
This argument can be set to zero to remove the limit and to process all request headers received:
local args = ngx.req.get_headers(0)
Removing the count_limit cap is strongly discouraged.
syntax: ngx.req.set_header(header_name, header_value)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Set the current request's request header named header_name to value header_value, overriding any existing ones.
None of the current request's subrequests will be affected.
Here is an example of setting the Content-Length header:
ngx.req.set_header("Content-Type", "text/css")
The header_value can take an array list of values,
for example,
ngx.req.set_header("Foo", {"a", "abc"})
will produce two new request headers:
Foo: a
Foo: abc
and old Foo headers will be overridden if there is any.
When the header_value argument is nil, the request header will be removed. So
ngx.req.set_header("X-Foo", nil)
is equivalent to
ngx.req.clear_header("X-Foo")
syntax: ngx.req.read_body()
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Reads the client request body synchronously without blocking the Nginx event loop.
ngx.req.read_body()
local args = ngx.req.get_post_args()
If the request body is already read previously by turning on lua_need_request_body or by using other modules, then this function does not run and returns immediately.
If the request body has already been explicitly discarded, either by the ngx.req.discard_body function or other modules, this function does not run and returns immediately.
In case of errors, such as connection errors while reading the data, this method will throw out a Lua exception or terminate the current request with a 500 status code immediately.
The request body data read using this function can be retrieved later via ngx.req.get_body_data or, alternatively, the temporary file name for the body data cached to disk using ngx.req.get_body_file. This depends on
- whether the current request body is already larger than the client_body_buffer_size,
- and whether client_body_in_file_only has been switched on.
In cases where current request may have a request body and the request body data is not required, The ngx.req.discard_body function must be used to explicitly discard the request body to avoid breaking things under HTTP 1.1 keepalive or HTTP 1.1 pipelining.
This function was first introduced in the v0.3.1rc17 release.
syntax: ngx.req.discard_body()
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Explicitly discard the request body, i.e., read the data on the connection and throw it away immediately. Please note that ignoring request body is not the right way to discard it, and that this function must be called to avoid breaking things under HTTP 1.1 keepalive or HTTP 1.1 pipelining.
This function is an asynchronous call and returns immediately.
If the request body has already been read, this function does nothing and returns immediately.
This function was first introduced in the v0.3.1rc17 release.
See also ngx.req.read_body.
syntax: data = ngx.req.get_body_data()
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Retrieves in-memory request body data. It returns a Lua string rather than a Lua table holding all the parsed query arguments. Use the ngx.req.get_post_args function instead if a Lua table is required.
This function returns nil if
- the request body has not been read,
- the request body has been read into disk temporary files,
- or the request body has zero size.
If the request body has not been read yet, call ngx.req.read_body first (or turned on lua_need_request_body to force this module to read the request body automatically, but this is not recommended).
If the request body has been read into disk files, try calling the ngx.req.get_body_file function instead.
To force in-memory request bodies, try setting client_body_buffer_size to the same size value in client_max_body_size.
Note that calling this function instead of using ngx.var.request_body or ngx.var.echo_request-body is more efficient because it can save one dynamic memory allocation and one data copy.
This function was first introduced in the v0.3.1rc17 release.
See also ngx.req.get_body_file.
syntax: file_name = ngx.req.get_body_file()
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Retrieves the file name for the in-file request body data. Returns nil if the request body has not been read or has been read into memory.
The returned file is read only and is usually cleaned up automatically by Nginx's memory pool. It should not be manually modified, renamed, or removed in Lua code.
If the request body has not been read yet, call ngx.req.read_body first (or turned on lua_need_request_body to force this module to read the request body automatically, but this is not recommended).
If the request body has been read into memory, try calling the ngx.req.get_body_data function instead.
To force in-file request bodies, try turning on client_body_in_file_only.
This function was first introduced in the v0.3.1rc17 release.
See also ngx.req.get_body_data.
syntax: ngx.req.set_body_data(data)
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Set the current request's request body using the in-memory data specified by the data argument.
If the current request's request body has not been read, then it will be properly discarded. When the current request's request body has been read into memory or buffered into a disk file, then the old request body's memory will be freed or the disk file will be cleaned up immediately, respectively.
This function requires patching the Nginx core to function properly because the Nginx core does not allow modifying request bodies by the current design. Here is a patch for Nginx 1.0.11: nginx-1.0.11-allow_request_body_updating.patch, and this patch should be applied cleanly to other releases of Nginx as well.
This patch has already been applied to ngx_openresty 1.0.8.17 and above.
This function was first introduced in the v0.3.1rc18 release.
See also ngx.req.set_body_file.
syntax: ngx.req.set_body_file(file_name, auto_clean?)
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Set the current request's request body using the in-file data specified by the file_name argument.
If the optional auto_clean argument is given a true value, then this file will be automatically removed at request completion or the next time this function or ngx.req.set_body_data are called in the same request. The auto_clean is default to false.
Please ensure that the file specified by the file_name argument exists and is readable by an Nginx worker process by setting its permission properly to avoid Lua exception errors.
If the current request's request body has not been read, then it will be properly discarded. When the current request's request body has been read into memory or buffered into a disk file, then the old request body's memory will be freed or the disk file will be cleaned up immediately, respectively.
This function requires patching the Nginx core to function properly because the Nginx core does not allow modifying request bodies by the current design. Here is a patch for Nginx 1.0.9: nginx-1.0.9-allow_request_body_updating.patch, and this patch should be applied cleanly to other releases of Nginx as well. This patch has already been applied to ngx_openresty 1.0.8.17 and above.
This function was first introduced in the v0.3.1rc18 release.
See also ngx.req.set_body_data.
syntax: tcpsock, err = ngx.req.socket()
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Returns a read-only cosocket object that wraps the downstream connection. Only receive and receiveuntil methods are supported on this object.
In case of error, nil will be returned as well as a string describing the error.
The socket object returned by this method is usually used to read the current request's body in a streaming fashion. Do not turn on the lua_need_request_body directive, and do not mix this call with ngx.req.read_body and ngx.req.discard_body.
If there is any request body data that has been preread into the Nginx core's request header buffer, the resulting cosocket object will take care of that automatically. So there will not be any data loss due to potential body data prereading.
This function was first introduced in the v0.5.0rc1 release.
syntax: ngx.req.clear_header(header_name)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Clear the current request's request header named header_name. None of the current request's subrequests will be affected.
syntax: ngx.exec(uri, args?)
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Does an internal redirect to uri with args.
ngx.exec('/some-location');
ngx.exec('/some-location', 'a=3&b=5&c=6');
ngx.exec('/some-location?a=3&b=5', 'c=6');
Named locations are also supported, but query strings are ignored. For example,
location /foo {
content_by_lua '
ngx.exec("@bar");
';
}
location @bar {
...
}
The optional second args can be used to specify extra URI query arguments, for example:
ngx.exec("/foo", "a=3&b=hello%20world")
Alternatively, a Lua table can passed for the args argument for ngx_lua to carry out URI escaping and string concatenation automatically.
ngx.exec("/foo", { a = 3, b = "hello world" })
The result is exactly the same as the previous example. The format for the Lua table passed as the args argument is identical to the format used in the ngx.encode_args method.
Note that this is very different from ngx.redirect in that it is just an internal redirect and no new HTTP traffic is involved.
This method never returns.
This method must be called before ngx.send_headers or explicit response body outputs by either ngx.print or ngx.say.
It's strongly recommended to combine the return statement with this call, i.e., return ngx.exec(...).
This method is similar to the echo_exec directive of the HttpEchoModule.
syntax: ngx.redirect(uri, status?)
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Issue an HTTP 301 or 302 redirection to uri.
The optional status parameter specifies whether
301 or 302 to be used. It is 302 (ngx.HTTP_MOVED_TEMPORARILY) by default.
Here is an example assuming the current server name is localhost and that it is listening on Port 1984:
return ngx.redirect("/foo")
which is equivalent to
return ngx.redirect("http://localhost:1984/foo", ngx.HTTP_MOVED_TEMPORARILY)
We can also use the numberical code directly as the second status argument:
return ngx.redirect("/foo", 301)
This method must be called before ngx.send_headers or explicit response body outputs by either ngx.print or ngx.say.
This method never returns.
This method is very much like the rewrite directive with the redirect modifier in the standard
HttpRewriteModule, for example, this nginx.conf snippet
rewrite ^ /foo? redirect; # nginx config
is equivalent to the following Lua code
return ngx.redirect('/foo'); -- lua code
while
rewrite ^ /foo? permanent; # nginx config
is equivalent to
return ngx.redirect('/foo', ngx.HTTP_MOVED_PERMANENTLY) -- Lua code
URI arguments can be specified as well, for example:
return ngx.redirect('/foo?a=3&b=4')
It's strongly recommended to combine the return statement with this call, i.e., return ngx.redirect(...).
syntax: ngx.send_headers()
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Explicitly send out the response headers.
Note that there is normally no need to manually send out response headers as ngx_lua will automatically send headers out
before content is output with ngx.say or ngx.print or when content_by_lua exits normally.
syntax: value = ngx.headers_sent
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Returns true if the response headers have been sent (by ngx_lua), and false otherwise.
This API was first introduced in ngx_lua v0.3.1rc6.
syntax: ngx.print(...)
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Emits arguments concatenated to the HTTP client (as response body). If response headers have not been sent, this function will send headers out first and then output body data.
Lua nil values will output "nil" strings and Lua boolean values will output "true" and "false" literal strings respectively.
Nested arrays of strings are permitted and the elements in the arrays will be sent one by one:
local table = {
"hello, ",
{"world: ", true, " or ", false,
{": ", nil}}
}
ngx.print(table)
will yield the output
hello, world: true or false: nil
Non-array table arguments will cause a Lua exception to be thrown.
The ngx.null constant will yield the "null" string output.
This is an asynchronous call and will return immediately without waiting for all the data to be written into the system send buffer. To run in synchronous mode, call ngx.flush(true) after calling ngx.print. This can be particularly useful for streaming output. See ngx.flush for more details.
syntax: ngx.say(...)
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Just as ngx.print but also emit a trailing newline.
syntax: ngx.log(log_level, ...)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Log arguments concatenated to error.log with the given logging level.
Lua nil arguments are accepted and result in literal "nil" string while Lua booleans result in literal "true" or "false" string outputs. And the ngx.null constant will yield the "null" string output.
The log_level argument can take constants like ngx.ERR and ngx.WARN. Check out Nginx log level constants for details.
There is a hard-coded length limitation on the error messages in the Nginx core. It is 2048 bytes at most, including the trailing newlines and the leading timestamps. You can manually modify this limit by modifying the NGX_MAX_ERROR_STR macro definition in the src/core/ngx_log.h file in the Nginx source tree. If the message size exceeds this limit, the Nginx core will truncate the message text automatically.
syntax: ngx.flush(wait?)
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Flushes response output to the client.
ngx.flush accepts an optional boolean wait argument (Default: false) first introduced in the v0.3.1rc34 release. When called with the default argument, it issues an asynchronous call (Returns immediately without waiting for output data to be written into the system send buffer). Calling the function with the wait argument set to true switches to synchronous mode.
In synchronous mode, the function will not return until all output data has been written into the system send buffer or until the send_timeout setting has expired. Note that using the Lua coroutine mechanism means that this function does not block the Nginx event loop even in the synchronous mode.
When ngx.flush(true) is called immediately after ngx.print or ngx.say, it causes the latter functions to run in synchronous mode. This can be particularly useful for streaming output.
Note that ngx.flush is non functional when in the HTTP 1.0 output buffering mode. See HTTP 1.0 support.
syntax: ngx.exit(status)
context: rewrite_by_lua, access_by_lua*, content_by_lua**
When status >= 200 (i.e., ngx.HTTP_OK and above), it will interrupt the execution of the current request and return status code to nginx.
When status == 0 (i.e., ngx.OK), it will only quit the current phase handler (or the content handler if the content_by_lua directive is used) and continue to run later phases (if any) for the current request.
The status argument can be ngx.OK, ngx.ERROR, ngx.HTTP_NOT_FOUND,
ngx.HTTP_MOVED_TEMPORARILY, or other HTTP status constants.
To return an error page with custom contents, use code snippets like this:
ngx.status = ngx.HTTP_GONE
ngx.say("This is our own content")
-- to cause quit the whole request rather than the current phase handler
ngx.exit(ngx.HTTP_OK)
The effect in action:
$ curl -i http://localhost/test
HTTP/1.1 410 Gone
Server: nginx/1.0.6
Date: Thu, 15 Sep 2011 00:51:48 GMT
Content-Type: text/plain
Transfer-Encoding: chunked
Connection: keep-alive
This is our own content
Number literals can be used directly as the argument, for instance,
ngx.exit(501)
Note that while this method accepts all HTTP status constants as input, it only accepts NGX_OK and NGX_ERROR of the core constants.
It's strongly recommended to combine the return statement with this call, i.e., return ngx.exit(...).
syntax: ngx.eof()
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Explicitly specify the end of the response output stream.
syntax: newstr = ngx.escape_uri(str)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Escape str as a URI component.
syntax: newstr = ngx.unescape_uri(str)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Unescape str as an escaped URI component.
For example,
ngx.say(ngx.unescape_uri("b%20r56+7"))
gives the output
b r56 7
syntax: str = ngx.encode_args(table)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Encode the Lua table to a query args string according to the URI encoded rules.
For example,
ngx.encode_args({foo = 3, ["b r"] = "hello world"})
yields
foo=3&b%20r=hello%20world
The table keys must be Lua strings.
Multi-value query args are also supported. Just use a Lua table for the arg's value, for example:
ngx.encode_args({baz = {32, "hello"}})
gives
baz=32&baz=hello
If the value table is empty and the effect is equivalent to the nil value.
Boolean argument values are also supported, for instance,
ngx.encode_args({a = true, b = 1})
yields
a&b=1
If the argument value is false, then the effect is equivalent to the nil value.
This method was first introduced in the v0.3.1rc27 release.
syntax: newstr = ngx.encode_base64(str)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Encode str to a base64 digest.
syntax: newstr = ngx.decode_base64(str)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Decodes the str argument as a base64 digest to the raw form. Returns nil if str is not well formed.
syntax: intval = ngx.crc32_short(str)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Calculates the CRC-32 (Cyclic Redundancy Code) digest for the str argument.
This method performs better on relatively short str inputs (i.e., less than 30 ~ 60 bytes), as compared to ngx.crc32_long. The result is exactly the same as ngx.crc32_long.
Behind the scene, it is just a thin wrapper around the ngx_crc32_short function defined in the Nginx core.
This API was first introduced in the v0.3.1rc8 release.
syntax: intval = ngx.crc32_long(str)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Calculates the CRC-32 (Cyclic Redundancy Code) digest for the str argument.
This method performs better on relatively long str inputs (i.e., longer than 30 ~ 60 bytes), as compared to ngx.crc32_short. The result is exactly the same as ngx.crc32_short.
Behind the scene, it is just a thin wrapper around the ngx_crc32_long function defined in the Nginx core.
This API was first introduced in the v0.3.1rc8 release.
syntax: digest = ngx.hmac_sha1(secret_key, str)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Computes the HMAC-SHA1 digest of the argument str and turns the result using the secret key <secret_key>.
The raw binary form of the HMAC-SHA1 digest will be generated, use ngx.encode_base64, for example, to encode the result to a textual representation if desired.
For example,
local key = "thisisverysecretstuff"
local src = "some string we want to sign"
local digest = ngx.hmac_sha1(key, src)
ngx.say(ngx.encode_base64(digest))
yields the output
R/pvxzHC4NLtj7S+kXFg/NePTmk=
This API requires the OpenSSL library enabled in the Nignx build (usually by passing the --with-http_ssl_module option to the ./configure script).
This function was first introduced in the v0.3.1rc29 release.
syntax: digest = ngx.md5(str)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Returns the hexadecimal representation of the MD5 digest of the str argument.
For example,
location = /md5 {
content_by_lua 'ngx.say(ngx.md5("hello"))';
}
yields the output
5d41402abc4b2a76b9719d911017c592
See ngx.md5_bin if the raw binary MD5 digest is required.
syntax: digest = ngx.md5_bin(str)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Returns the binary form of the MD5 digest of the str argument.
See ngx.md5 if the hexadecimal form of the MD5 digest is required.
syntax: digest = ngx.sha1_bin(str)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Returns the binary form of the SHA-1 digest of the str argument.
This function was first introduced in the v0.5.0rc6.
syntax: str = ngx.today()
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Returns current date (in the format yyyy-mm-dd) from the nginx cached time (no syscall involved unlike Lua's date library).
This is the local time.
syntax: secs = ngx.time()
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Returns the elapsed seconds from the epoch for the current timestamp from the nginx cached time (no syscall involved unlike Lua's date library).
Updates of the Nginx time cache an be forced by calling ngx.update_time first.
syntax: secs = ngx.now()
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Returns a floating-point number for the elapsed time in seconds (including microseconds as the decimal part) from the epoch for the current timestamp from the nginx cached time (no syscall involved unlike Lua's date library).
Use the Nginx core timer_resolution directive to adjust the accuracy or forcibly update the Nginx time cache by calling ngx.update_time first.
This API was first introduced in v0.3.1rc32.
syntax: ngx.update_time()
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Forcibly updates the Nginx current time cache. This call involves a syscall and thus has some overhead, so do not abuse it.
This API was first introduced in v0.3.1rc32.
syntax: str = ngx.localtime()
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Returns the current timestamp (in the format yyyy-mm-dd hh:mm:ss) of the nginx cached time (no syscall involved unlike Lua's os.date function).
This is the local time.
syntax: str = ngx.utctime()
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Returns the current timestamp (in the format yyyy-mm-dd hh:mm:ss) of the nginx cached time (no syscall involved unlike Lua's os.date function).
This is the UTC time.
syntax: str = ngx.cookie_time(sec)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Returns a formated string can be used as the cookie expiration time. The parameter sec is the timestamp in seconds (like those returned from ngx.time).
ngx.say(ngx.cookie_time(1290079655))
-- yields "Thu, 18-Nov-10 11:27:35 GMT"
syntax: str = ngx.http_time(sec)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Returns a formated string can be used as the http header time (for example, being used in Last-Modified header). The parameter sec is the timestamp in seconds (like those returned from ngx.time).
ngx.say(ngx.http_time(1290079655))
-- yields "Thu, 18 Nov 10 11:27:35 GMT"
syntax: sec = ngx.parse_http_time(str)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Parse the http time string (as returned by ngx.http_time) into seconds. Returns the seconds or nil if the input string is in bad forms.
local time = ngx.parse_http_time("Thu, 18 Nov 10 11:27:35 GMT")
if time == nil then
...
end
syntax: value = ngx.is_subrequest
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Returns true if the current request is an nginx subrequest, or false otherwise.
syntax: captures = ngx.re.match(subject, regex, options?, ctx?)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Matches the subject string using the Perl-compatible regular expression regex with the optional options.
Only the first occurrence of the match is returned, or nil if no match is found. In case of fatal errors, like seeing bad UTF-8 sequences in UTF-8 mode, a Lua exception will be raised.
When a match is found, a Lua table captures is returned, where captures[0] holds the whole substring being matched, and captures[1] holds the first parenthesized subpattern's capturing, captures[2] the second, and so on.
local m = ngx.re.match("hello, 1234", "[0-9]+")
-- m[0] == "1234"
local m = ngx.re.match("hello, 1234", "([0-9])[0-9]+")
-- m[0] == "1234"
-- m[1] == "1"
Unmatched subpatterns will have nil values in their captures table fields.
local m = ngx.re.match("hello, world", "(world)|(hello)")
-- m[0] == "hello"
-- m[1] == nil
-- m[2] == "hello"
Specify options to control how the match operation will be performed. The following option characters are supported:
a anchored mode (only match from the beginning)
d enable the DFA mode (or the longest token match semantics).
this requires PCRE 6.0+ or else a Lua exception will be thrown.
first introduced in ngx_lua v0.3.1rc30.
i caseless mode (similar to Perl's /i modifier)
j enable PCRE JIT compilation, this requires PCRE 8.21+ which
must be built with the --enable-jit option.
for optimum performance, this option should always be used
together with the 'o' option.
first introduced in ngx_lua v0.3.1rc30.
m multi-line mode (similar to Perl's /m modifier)
o compile-once mode (similar to Perl's /o modifer),
to enable the worker-process-level compiled-regex cache
s single-line mode (similar to Perl's /s modifier)
u UTF-8 mode. this requires PCRE to be built with
the --enable-utf8 option or else a Lua exception will be thrown.
x extended mode (similar to Perl's /x modifier)
These options can be combined:
local m = ngx.re.match("hello, world", "HEL LO", "ix")
-- m[0] == "hello"
local m = ngx.re.match("hello, 美好生活", "HELLO, (.{2})", "iu")
-- m[0] == "hello, 美好"
-- m[1] == "美好"
The o option is useful for performance tuning, because the regex pattern in question will only be compiled once, cached in the worker-process level, and shared among all requests in the current Nginx worker process. The upper limit of the regex cache can be tuned via the lua_regex_cache_max_entries directive.
The optional fourth argument, ctx, can be a Lua table holding an optional pos field. When the pos field in the ctx table argument is specified, ngx.re.match will start matching from that offset. Regardless of the presence of the pos field in the ctx table, ngx.re.match will always set this pos field to the position after the substring matched by the whole pattern in case of a successful match. When match fails, the ctx table will be left intact.
local ctx = {}
local m = ngx.re.match("1234, hello", "[0-9]+", "", ctx)
-- m[0] = "1234"
-- ctx.pos == 4
local ctx = { pos = 2 }
local m = ngx.re.match("1234, hello", "[0-9]+", "", ctx)
-- m[0] = "34"
-- ctx.pos == 4
The ctx table argument combined with the a regex modifier can be used to construct a lexer atop ngx.re.match.
Note that, the options argument is not optional when the ctx argument is specified and that the empty Lua string ("") must be used as placeholder for options if no meaningful regex options are required.
This method requires the PCRE library enabled in Nginx. (Known Issue With Special PCRE Sequences).
To confirm that PCRE JIT is indeed enabled, it's required to enable the debugging logs in your Nginx build (by passing the --with-debug option to your Nginx or ngx_openresty's ./configure script) and enable the "debug" error log level in your error_log directive, and then you can see the following message if PCRE JIT actually works:
pcre JIT compiling result: 1
This feature was introduced in the v0.2.1rc11 release.
syntax: iterator = ngx.re.gmatch(subject, regex, options?)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Similar to ngx.re.match, but returns a Lua iterator instead, so as to let the user programmer iterate all the matches over the <subject> string argument with the PCRE regex.
Here is a small exmple to demonstrate its basic usage:
local iterator = ngx.re.gmatch("hello, world!", "([a-z]+)", "i")
local m
m = iterator() -- m[0] == m[1] == "hello"
m = iterator() -- m[0] == m[1] == "world"
m = iterator() -- m == nil
More often we just put it into a Lua for loop:
for m in ngx.re.gmatch("hello, world!", "([a-z]+)", "i")
ngx.say(m[0])
ngx.say(m[1])
end
The optional options argument takes exactly the same semantics as the ngx.re.match method.
The current implementation requires that the iterator returned should only be used in a single request. That is, one should not assign it to a variable belonging to persistent namespace like a Lua package.
This method requires the PCRE library enabled in Nginx. (Known Issue With Special PCRE Sequences).
This feature was first introduced in the v0.2.1rc12 release.
syntax: newstr, n = ngx.re.sub(subject, regex, replace, options?)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Substitutes the first match of the Perl-compatible regular expression regex on the subject argument string with the string or function argument replace. The optional options argument has exactly the same meaning as in ngx.re.match.
This method returns the resulting new string as well as the number of successful substitutions, or throw out a Lua exception when an error occurred (syntax errors in the <replace> string argument, for example).
When the replace is a string, then it is treated as a special template for string replacement. For example,
local newstr, n = ngx.re.sub("hello, 1234", "([0-9])[0-9]", "[$0][$1]")
-- newstr == "hello, [12][1]34"
-- n == 1
where $0 referring to the whole substring matched by the pattern and $1 referring to the first parenthesized capturing substring.
Curly braces can also be used to disambiguate variable names from the background string literals:
local newstr, n = ngx.re.sub("hello, 1234", "[0-9]", "${0}00")
-- newstr == "hello, 10034"
-- n == 1
Literal dollar sign characters ($) in the replace string argument can be escaped by another dollar sign, for instance,
local newstr, n = ngx.re.sub("hello, 1234", "[0-9]", "$$")
-- newstr == "hello, $234"
-- n == 1
Do not use backlashes to escape dollar signs; it will not work as expected.
When the replace argument is of type "function", then it will be invoked with the "match table" as the argument to generate the replace string literal for substitution. The "match table" fed into the replace function is exactly the same as the return value of ngx.re.match. Here is an example:
local func = function (m)
return "[" .. m[0] .. "][" .. m[1] .. "]"
end
local newstr, n = ngx.re.sub("hello, 1234", "( [0-9] ) [0-9]", func, "x")
-- newstr == "hello, [12][1]34"
-- n == 1
The dollar sign characters in the return value of the replace function argument are not special at all.
This method requires the PCRE library enabled in Nginx. (Known Issue With Special PCRE Sequences).
This feature was first introduced in the v0.2.1rc13 release.
syntax: newstr, n = ngx.re.gsub(subject, regex, replace, options?)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Just like ngx.re.sub, but does global substitution.
Here is some examples:
local newstr, n = ngx.re.gsub("hello, world", "([a-z])[a-z]+", "[$0,$1]", "i")
-- newstr == "[hello,h], [world,w]"
-- n == 2
local func = function (m)
return "[" .. m[0] .. "," .. m[1] .. "]"
end
local newstr, n = ngx.re.gsub("hello, world", "([a-z])[a-z]+", func, "i")
-- newstr == "[hello,h], [world,w]"
-- n == 2
This method requires the PCRE library enabled in Nginx. (Known Issue With Special PCRE Sequences).
This feature was first introduced in the v0.2.1rc15 release.
syntax: dict = ngx.shared.DICT
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Fetching the shm-based Lua dictionary object for the shared memory zone named DICT defined by the lua_shared_dict directive.
The resulting object dict has the following methods:
Here is an example:
http {
lua_shared_dict dogs 10m;
server {
location /set {
content_by_lua '
local dogs = ngx.shared.dogs
dogs:set("Jim", 8)
ngx.say("STORED")
';
}
location /get {
content_by_lua '
local dogs = ngx.shared.dogs
ngx.say(dogs:get("Jim"))
';
}
}
}
Let us test it:
$ curl localhost/set
STORED
$ curl localhost/get
8
$ curl localhost/get
8
The number 8 will be consistently output when accessing /get regardless of how many Nginx workers there are because the dogs dictionary resides in the shared memory and visible to all of the worker processes.
The shared dictionary will retain its contents through a server config reload (either by sending the HUP signal to the Nginx process or by using the -s reload command-line option).
The contents in the dictionary storage will be lost, however, when the Nginx server quits.
This feature was first introduced in the v0.3.1rc22 release.
syntax: value, flags = ngx.shared.DICT:get(key)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Retrieving the value in the dictionary ngx.shared.DICT for the key key. If the key does not exist or has been expired, then nil will be returned.
The value returned will have the original data type when they were inserted into the dictionary, for example, Lua booleans, numbers, or strings.
The first argument to this method must be the dictionary object itself, for example,
local cats = ngx.shared.cats
local value, flags = cats.get(cats, "Marry")
or use Lua's syntactic sugar for method calls:
local cats = ngx.shared.cats
local value, flags = cats:get("Marry")
These two forms are fundamentally equivalent.
If the user flags is 0 (the default), then no flags value will be returned.
This feature was first introduced in the v0.3.1rc22 release.
See also ngx.shared.DICT.
syntax: success, err, forcible = ngx.shared.DICT:set(key, value, exptime?, flags?)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Unconditionally sets a key-value pair into the shm-based dictionary ngx.shared.DICT. Returns three values:
success: boolean value to indicate whether the key-value pair is stored or not.err: textual error message, can be"no memory".forcible: a boolean value to indicate whether other valid items have been removed forcibly when out of storage in the shared memory zone.
The value argument inserted can be Lua booleans, numbers, strings, or nil. Their value type will also be stored into the dictionary and the same data type can be retrieved later via the get method.
The optional exptime argument specifies expiration time (in seconds) for the inserted key-value pair. The time resolution is 0.001 seconds. If the exptime takes the value 0 (which is the default), then the item will never be expired.
The optional flags argument specifies a user flags value associated with the entry to be stored. It can also be retrieved later with the value. The user flags is stored as an unsigned 32-bit integer internally. Defaults to 0. The user flags argument was first introduced in the v0.5.0rc2 release.
When it fails to allocate memory for the current key-value item, then set will try removing existing items in the storage according to the Least-Recently Used (LRU) algorithm. Note that, LRU takes priority over expiration time here. If up to tens of existing items have been removed and the storage left is still insufficient (either due to the total capacity limit specified by lua_shared_dict or memory segmentation), then the err return value will be no memory and success will be false.
If this method succeeds in storing the current item by forcibly removing other not-yet-expired items in the dictionary via LRU, the forcible return value will be true. If it stores the item without forcibly removing other valid items, then the return value forcible will be false.
The first argument to this method must be the dictionary object itself, for example,
local cats = ngx.shared.cats
local succ, err, forcible = cats.set(cats, "Marry", "it is a nice cat!")
or use Lua's syntactic sugar for method calls:
local cats = ngx.shared.cats
local succ, err, forcible = cats:set("Marry", "it is a nice cat!")
These two forms are fundamentally equivalent.
This feature was first introduced in the v0.3.1rc22 release.
See also ngx.shared.DICT.
syntax: success, err, forcible = ngx.shared.DICT:add(key, value, exptime?, flags?)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Just like the set method, but only stores the key-value pair into the dictionary ngx.shared.DICT if the key does not exist.
If the key argument already exists in the dictionary (and not expired for sure), the success return value will be false and the err return value will be "exists".
This feature was first introduced in the v0.3.1rc22 release.
See also ngx.shared.DICT.
syntax: success, err, forcible = ngx.shared.DICT:replace(key, value, exptime?, flags?)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Just like the set method, but only stores the key-value pair into the dictionary ngx.shared.DICT if the key does exist.
If the key argument does not exist in the dictionary (or expired already), the success return value will be false and the err return value will be "not found".
This feature was first introduced in the v0.3.1rc22 release.
See also ngx.shared.DICT.
syntax: ngx.shared.DICT:delete(key)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Unconditionally removes the key-value pair from the shm-based dictionary ngx.shared.DICT.
It is equivalent to ngx.shared.DICT:set(key, nil).
This feature was first introduced in the v0.3.1rc22 release.
See also ngx.shared.DICT.
syntax: newval, err = ngx.shared.DICT:incr(key, value)
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Increments the (numerical) value for key in the shm-based dictionary ngx.shared.DICT by the step value value. Returns the new resulting number if the operation is successfully completed or nil and an error message otherwise.
The key must already exist in the dictionary, otherwise it will return nil and "not found".
If the original value is not a valid Lua number in the dictionary, it will return nil and "not a number".
The value argument can be any valid Lua numbers, like negative numbers or floating-point numbers.
This feature was first introduced in the v0.3.1rc22 release.
See also ngx.shared.DICT.
syntax: ngx.shared.DICT:flush_all()
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
Flushes out all the items in the dictionary.
This feature was first introduced in the v0.5.0rc17 release.
See also ngx.shared.DICT.
syntax: tcpsock = ngx.socket.tcp()
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Creates and returns a TCP (or Unix Domain) socket object (also known as the "cosocket" object). The following methods are supported on this object:
It is intended to be compatible with the TCP API of the LuaSocket library but is 100% nonblocking out of the box. Also, we introduce some new APIs to provide more functionalities.
This feature was first introduced in the v0.5.0rc1 release.
syntax: ok, err = tcpsock:connect(host, port)
syntax: ok, err = tcpsock:connect("unix:/path/to/unix-domain.socket")
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Attempts to connect a TCP socket object to a remote server or to a unix domain socket file nonblockingly.
Before actually resolving the host name and connecting to the remote backend, this method will always look up the connection pool for matched idle connections created by previous calls of this method (or the ngx.socket.connect function).
Both IP addresses and domain names can be specified as the host argument. In case of domain names, this method will use Nginx core's dynamic resolver to parse the domain name nonblockingly and it is required to configure the resolver directive in your nginx.conf file like this:
resolver 8.8.8.8; # use Google's public DNS nameserver
If the nameserver returns multiple IP addresses for the host name, this method will pick up one randomly.
In case of error, the method returns nil followed by a string describing the error. In case of success, the method returns 1.
Here is an example for connecting to a TCP server:
location /test {
resolver 8.8.8.8;
content_by_lua '
local sock = ngx.socket.tcp()
local ok, err = sock:connect("www.google.com", 80)
if not ok then
ngx.say("failed to connect to google: ", err)
return
end
ngx.say("successfully connected to google!")
sock:close()
';
}
Connecting to a Unix Domain Socket file is also possible:
local sock = ngx.socket.tcp()
local ok, err = sock:connect("unix:/tmp/memcached.sock")
if not ok then
ngx.say("failed to connect to the memcached unix domain socket: ", err)
return
end
assuming that your memcached (or something else) is listening on the unix domain socket file /tmp/memcached.sock.
Timeout for the connecting operation is controlled by the lua_socket_connect_timeout config directive and the settimeout method. And the latter takes priority. For example:
local sock = ngx.socket.tcp()
sock:settimeout(1000) -- one second timeout
local ok, err = sock:connect(host, port)
It is important here to call the settimeout method before calling this method.
Calling this method on an already connected socket object will cause the original connection to be closed first.
This feature was first introduced in the v0.5.0rc1 release.
syntax: bytes, err = tcpsock:send(data)
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Sends data nonblockingly on the current TCP or Unix Domain Socket connection.
This method is a synchronous operation that will not return until all the data has been flushed into the system socket send buffer or an error occurs.
In case of success, it returns the total number of bytes that have been sent. Otherwise, it returns nil and a string describing the error.
The input argument data can either be a Lua string or a (nested) Lua table holding string fragments. In case of table arguments, this method will automatically copy all the string elements piece by piece to the underlying Nginx socket send buffers, which is usually optimal than doing string concatenation operations on the Lua land.
Timeout for the sending operation is controlled by the lua_socket_send_timeout config directive and the settimeout method. And the latter takes priority. For example:
sock:settimeout(1000) -- one second timeout
local bytes, err = sock:send(request)
It is important here to call the settimeout method before calling this method.
This feature was first introduced in the v0.5.0rc1 release.
syntax: data, err, partial = tcpsock:receive(size)
syntax: data, err, partial = tcpsock:receive(pattern?)
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Receives data from the connected socket according to the reading pattern or size.
This method is a synchronous operation just like the send method and is 100% nonblocking.
In case of success, it returns the data received; in case of error, it returns nil with a string describing the error and the partial data received so far.
If a number-like argument is specified (including strings that look like numbers), then it is interpreted as a size. This method will not return until it reads exactly this size of data or an error occurs.
If a non-number-like string argument is specified, then it is interpreted as a "pattern". The following patterns are supported:
'*a': reads from the socket until the connection is closed. No end-of-line translation is performed;'*l': reads a line of text from the socket. The line is terminated by aLine Feed(LF) character (ASCII 10), optionally preceded by aCarriage Return(CR) character (ASCII 13). The CR and LF characters are not included in the returned line. In fact, all CR characters are ignored by the pattern.
If no argument is specified, then it is assumed to be the pattern '*l', that is, the line reading pattern.
Timeout for the reading operation is controlled by the lua_socket_read_timeout config directive and the settimeout method. And the latter takes priority. For example:
sock:settimeout(1000) -- one second timeout
local line, err, partial = sock:receive()
if not line then
ngx.say("failed to read a line: ", err)
return
end
ngx.say("successfully read a line: ", line)
It is important here to call the settimeout method before calling this method.
This feature was first introduced in the v0.5.0rc1 release.
syntax: iterator = tcpsock:receiveuntil(pattern)
context: rewrite_by_lua, access_by_lua*, content_by_lua**
This method returns an iterator Lua function that can be called to read the data stream until it sees the specified pattern or an error occurs.
Here is an example for using this method to read a data stream with the boundary sequence --abcedhb:
local reader = sock:receiveuntil("\r\n--abcedhb")
local data, err, partial = reader()
if not data then
ngx.say("failed to read the data stream: ", err)
end
ngx.say("read the data stream: ", data)
When called without any argument, the iterator function returns the received data right before the specified pattern string in the incoming data stream. So for the example above, if the incoming data stream is 'hello, world! -agentzh\r\n--abcedhb blah blah', then the string 'hello, world! -agentzh' will be returned.
In case of error, the iterator function will return nil along with a string describing the error and the partial data bytes that have been read so far.
The iterator function can be called multiple times and can be mixed safely with other cosocket method calls or other iterator function calls.
The iterator function behaves differently (i.e., like a real iterator) when it is called with a size argument. That is, it will read that size of data at earch invocation and will return nil at the last invocation (either sees the boundary pattern or meets an error). For the last successful invocation of the iterator function, the err return value will be nil too. The iterator function will automatically reset after its last successful invocation that returns nil data and nil error. Consider the following example:
local reader = sock:receiveuntil("\r\n--abcedhb")
while true then
local data, err, partial = reader(4)
if not data then
if err then
ngx.say("failed to read the data stream: ", err)
break
end
ngx.say("read done")
break
end
ngx.say("read chunk: [", data, "]")
end
Then for the incoming data stream 'hello, world! -agentzh\r\n--abcedhb blah blah', we shall get the following output from the sample code above:
read chunk: [hell]
read chunk: [o, w]
read chunk: [orld]
read chunk: [! -a]
read chunk: [gent]
read chunk: [zh]
read done
Note that, the actual data returned might be a little longer than the size limit specified by the size argument when your boundary pattern has ambiguity for streaming parsing. Near the boundary of the data stream, the data string actually returned could also be shorter than the size limit.
Timeout for the iterator function's reading operation is controlled by the lua_socket_read_timeout config directive and the settimeout method. And the latter takes priority. For example:
local readline = sock:receiveuntil("\r\n")
sock:settimeout(1000) -- one second timeout
line, err, partial = readline()
if not line then
ngx.say("failed to read a line: ", err)
return
end
ngx.say("successfully read a line: ", line)
It is important here to call the settimeout method before calling the iterator function (note that the receiveuntil call is irrelevant here).
This feature was first introduced in the v0.5.0rc1 release.
syntax: ok, err = tcpsock:close()
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Closes the current TCP or Unix Domain socket. It returns the 1 in case of success and returns nil with a string describing the error otherwise.
For socket objects that have invoked the setkeepalive method, there is no need to call this method on it because the socket object is already closed (and the current connection is saved into the builtin connection pool).
For socket objects that have not invoked setkeepalive, they (and their connections) will be automatically closed when the socket object is released by the Lua GC (Garbage Collector) or the current client HTTP request finishes processing.
This feature was first introduced in the v0.5.0rc1 release.
syntax: tcpsock:settimeout(time)
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Set the timeout value in milliseconds for subsequent socket operations (connect, receive, and iterators returned from receiveuntil).
Settings done by this method takes priority over those config directives, i.e., lua_socket_connect_timeout, lua_socket_send_timeout, and lua_socket_read_timeout.
Note that this method does not affect the lua_socket_keepalive_timeout setting; the timeout argument to the setkeepalive method should be used for this purpose instead.
This feature was first introduced in the v0.5.0rc1 release.
syntax: tcpsock:setoption(option, value?)
context: rewrite_by_lua, access_by_lua*, content_by_lua**
This function is added for LuaSocket API compatibility and does nothing for now. Its functionality will be implemented in future.
This feature was first introduced in the v0.5.0rc1 release.
syntax: ok, err = tcpsock:setkeepalive(timeout?, size?)
context: rewrite_by_lua, access_by_lua*, content_by_lua**
Puts the current socket's connection into the cosocket built-in connection pool and keep it alive until other connect method calls request it or the associated maximal idle timeout is expired.
The first optional argument, timeout, can be used to specify the maximal idle timeout (in milliseconds) for the current connection. If omitted, the default setting in the lua_socket_keepalive_timeout config directive will be used. If the 0 value is given, then the timeout interval is unlimited.
The second optional argument, size, can be used to specify the maximal number of connections allowed in the connection pool for the current server (i.e., the current host-port pair or the unix domain socket file path). Note that the size of the connection pool cannot be changed once the pool is created. When this argument is omitted, the default setting in the lua_socket_pool_size config directive will be used.
When the connection pool is exceeding the size limit, the least recently used (idle) connection already in the pool will be closed automatically to make room for the current connection.
Note that the cosocket connection pool is per Nginx worker process rather than per Nginx server instance, so the size limit specified here also applies to every single Nginx worker process.
Idle connections in the pool will be monitored for any exceptional events like connection abortion or unexpected incoming data on the line, in which cases the connection in question will be closed and removed from the pool.
In case of success, this method returns 1; otherwise, it returns nil and a string describing the error.
This method also makes the current cosocket object enter the "closed" state, so you do not need to manually call the close method on it afterwards.
This feature was first introduced in the v0.5.0rc1 release.
syntax: count, err = tcpsock:getreusedtimes()
context: rewrite_by_lua, access_by_lua*, content_by_lua**
This method returns the (successfully) reused times for the current connection. In case of error, it returns nil and a string describing the error.
If the current connection does not come from the built-in connection pool, then this method always returns 0, that is, the connection has never been reused (yet). If the connection comes from the connection pool, then the return value is always non-zero. So this method can also be used to determine if the current connection comes from the pool.
This feature was first introduced in the v0.5.0rc1 release.
syntax: tcpsock, err = ngx.socket.connect(host, port)
syntax: tcpsock, err = ngx.socket.connect("unix:/path/to/unix-domain.socket")
context: rewrite_by_lua, access_by_lua*, content_by_lua**
This function is a shortcut for combining ngx.socket.tcp() and the connect() method call in a single operation. It is actually implemented like this:
local sock = ngx.socket.tcp()
local ok, err = sock:connect(...)
if not ok then
return nil, err
end
return sock
There is no way to use the settimeout method to specify connecting timeout for this method. You have to use the lua_socket_connect_timeout directive at configure time instead.
This feature was first introduced in the v0.5.0rc1 release.
syntax: res = ndk.set_var.DIRECTIVE_NAME
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua**
This mechanism allows calling other nginx C modules' directives that are implemented by Nginx Devel Kit (NDK)'s set_var submodule's ndk_set_var_value.
For example, the following HttpSetMiscModule directives can be invoked this way:
- set_quote_sql_str
- set_quote_pgsql_str
- set_quote_json_str
- set_unescape_uri
- set_escape_uri
- set_encode_base32
- set_decode_base32
- set_encode_base64
- set_decode_base64
- set_encode_hex
- set_decode_hex
- set_sha1
- set_md5
For instance,
local res = ndk.set_var.set_escape_uri('a/b');
-- now res == 'a%2fb'
Similarly, the following directives provided by HttpEncryptedSessionModule can be invoked from within Lua too:
This feature requires the ngx_devel_kit module.
The HTTP 1.0 protocol does not support chunked outputs and always requires an
explicit Content-Length header when the response body is non-empty. So when
an HTTP 1.0 request is present, This module will automatically buffer all the
outputs of user calls of ngx.say and ngx.print and
postpone sending response headers until it sees all the outputs in the response
body, and at that time ngx_lua can calculate the total length of the body and
construct a proper Content-Length header for the HTTP 1.0 client.
Note that, common HTTP benchmark tools like ab and http_load always issue
HTTP 1.0 requests by default. To force curl to send HTTP 1.0 requests, use
the -0 option.
NOTE: This mechanism behaves differently when code cache is turned off and should be considered a DIRTY TRICK. Note that backward compatibility is NOT guaranteed and that there may be other undesirable consequences. A new data sharing mechanism will be designed later.
To globally share data among all the requests handled by the same nginx worker process, encapsulate the shared data into a Lua module, use the Lua require builtin to import the module, and then manipulate the shared data in Lua. This works because required Lua modules are loaded only once and all coroutines will share the same copy of the module. Note however that Lua global variables WILL NOT persist between requests because of the one-coroutine-per-request isolation design.
Here is a complete small example:
-- mydata.lua
module("mydata", package.seeall)
local data = {
dog = 3,
cat = 4,
pig = 5,
}
function get_age(name)
return data[name]
end
and then accessing it from nginx.conf:
location /lua {
content_lua_by_lua '
local mydata = require("mydata")
ngx.say(mydata.get_age("dog"))
';
}
The mydata module in this example will only be loaded and run on the first request to the location /lua,
and all subsequent requests to the same nginx worker process will use the reloaded instance of the
module as well as the same copy of the data in it, until a HUP signal is sent to the Nginx master process to force a reload.
This data sharing technique is essential for high performance Lua applications based on this module.
Note that this data sharing is on a per-worker basis and not on a ''per-server' basis'. That is, when there are multiple nginx worker processes under an Nginx master, data sharing cannot cross the process boundary between these workers.
If server wide data sharing is required:
- Use the ngx.shared.DICT API provied by this module.
- Use only a single nginx worker and a single server. This is however not recommended when there is a multi core CPU or multiple CPUs in a single machine.
- Use data storage mechanisms such as
memcached,redis,MySQLorPostgreSQL. The ngx_openresty bundle associated with this module comes with a set of companion Nginx modules that provide interfaces with these data storage mechanisms. See the HttpMemcModule, HttpRedis2Module, HttpDrizzleModule and HttpPostgresModule modules for details
- As the module's predefined Nginx I/O API uses the coroutine yielding/resuming mechanism, user code should not call any Lua modules that use the Lua coroutine mechanism in order to prevent conflicts with the module's predefined Nginx API methods such as ngx.location.capture (Actually, coroutine modules have been masked off in content_by_lua directives and others). This limitation is significant and work is ongoing on an alternative coroutine implementation that can fit into the Nginx event model to address this. When this is done, it will be possible to use the Lua coroutine mechanism freely as it is in standard Lua implementations.
- Lua's
dofilebuiltin is implemented as a C function in both Lua 5.1 and LuaJIT 2.0 and when ngx.location.capture is called, ngx.exec, ngx.exit or ngx.req.read_body or similar in the file to be loaded bydofile, a coroutine yield across the C function boundary will be initiated. This however is not allowed within ngx_lua and will usually result in error messages likelua handler aborted: runtime error: attempt to yield across C-call boundary. To avoid this, define a real Lua module and use the Luarequirebuiltin instead. - Because the standard Lua 5.1 interpreter's VM is not fully resumable, the methods ngx.location.capture, ngx.location.capture_multi, ngx.redirect, ngx.exec, and ngx.exit cannot be used within the context of a Lua pcall() or xpcall() when the standard Lua 5.1 interpreter is used and the
attempt to yield across metamethod/C-call boundaryerror will be produced. Please use LuaJIT 2.0, which supports a fully resumable VM, to avoid this.
Care should be taken when importing modules and this form should be used:
local xxx = require('xxx')
instead of the old deprecated form:
require('xxx')
If the old form is required, force reload the module for every request by using the `package.loaded.<module>` command:
package.loaded.xxx = nil
require('xxx')
It is recommended to always place the following piece of code at the end of Lua modules that use the ngx.location.capture or ngx.location.capture_multi directives to prevent casual use of module-level global variables that are shared among all requests:
getmetatable(foo.bar).__newindex = function (table, key, val)
error('Attempt to write to undeclared variable "' .. key .. '": '
.. debug.traceback())
end
Assuming the current Lua module is named foo.bar, this will guarantee that local variables in module foo.bar functions have been declared as "local". It prevents undesirable race conditions while accessing such variables. See Data Sharing within an Nginx Worker for the reasons behind this.
The ngx.location.capture and ngx.location.capture_multi directives cannot capture locations that include the echo_location, echo_location_async, echo_subrequest, or echo_subrequest_async directives.
location /foo {
content_by_lua '
res = ngx.location.capature("/bar")
';
}
location /bar {
echo_location /blah;
}
location /blah {
echo "Success!";
}
$ curl -i http://example.com/foo
will not work as expected.
PCRE sequences such as \d, \s, or \w, require special attention because in string literals, the backslash character, \, is stripped out by both the Lua language parser and by the Nginx config file parser before processing. So the following snippet will not work as expected:
# nginx.conf
? location /test {
? content_by_lua '
? local regex = "\d+" -- THIS IS WRONG!!
? local m = ngx.re.match("hello, 1234", regex)
? if m then ngx.say(m[0]) else ngx.say("not matched!") end
? ';
? }
# evaluates to "not matched!"
To avoid this, double escape the backslash:
# nginx.conf
location /test {
content_by_lua '
local regex = "\\\\d+"
local m = ngx.re.match("hello, 1234", regex)
if m then ngx.say(m[0]) else ngx.say("not matched!") end
';
}
# evaluates to "1234"
Here, \\\\d+ is stripped down to \\d+ by the Nginx config file parser and this is further stripped down to \d+ by the Lua language parser before running.
Alternatively, the regex pattern can be presented as a long-bracketed lua string literal by encasing it in "long brackets", [[...]], in which case backslashes have to only be escaped once for the Nginx config file parser.
# nginx.conf
location /test {
content_by_lua '
local regex = [[\\d+]]
local m = ngx.re.match("hello, 1234", regex)
if m then ngx.say(m[0]) else ngx.say("not matched!") end
';
}
# evaluates to "1234"
Here, [[\\d+]] is stripped down to [[\d+]] by the Nginx config file parser and this is processed correctly.
Note that a longer from of the long bracket, [=[...]=], may be required if the regex pattern contains [...] sequences.
The [=[...]=] form may be used as the default form if desired and it may help with readability if a space is inserted between the long brackets and the regex patterns.
# nginx.conf
location /test {
content_by_lua '
local regex = [=[ [0-9]+ ]=]
local m = ngx.re.match("hello, 1234", regex)
if m then ngx.say(m[0]) else ngx.say("not matched!") end
';
}
# evaluates to "1234"
An alternative approach to escaping PCRE sequences is to ensure that Lua code is placed in external script files and executed using the various *_by_lua_file directives.
With this approach, the backslashes are only stripped by the Lua language parser and therefore only need to be escaped once each.
-- test.lua
local regex = "\\d+"
local m = ngx.re.match("hello, 1234", regex)
if m then ngx.say(m[0]) else ngx.say("not matched!") end
-- evaluates to "1234"
Within external script files, PCRE sequences presented as long-bracketed lua string literals do not require modification.
-- test.lua
local regex = [[\d+]]
local m = ngx.re.match("hello, 1234", regex)
if m then ngx.say(m[0]) else ngx.say("not matched!") end
-- evaluates to "1234"
Just to name a few:
- Mashup'ing and processing outputs of various nginx upstream outputs (proxy, drizzle, postgres, redis, memcached, and etc) in Lua,
- doing arbitrarily complex access control and security checks in Lua before requests actually reach the upstream backends,
- manipulating response headers in an arbitrary way (by Lua)
- fetching backend information from external storage backends (like redis, memcached, mysql, postgresql) and use that information to choose which upstream backend to access on-the-fly,
- coding up arbitrarily complex web applications in a content handler using synchronous but still non-blocking access to the database backends and other storage,
- doing very complex URL dispatch in Lua at rewrite phase,
- using Lua to implement advanced caching mechanism for nginx subrequests and arbitrary locations.
The possibilities are unlimited as the module allows bringing together various elements within Nginx as well as exposing the power of the Lua language to the user. The module provides the full flexibility of scripting while offering performance levels comparable with native C language programs both in terms of CPU time as well as memory footprint. This is particularly the case when LuaJIT 2.0 is enabled.
Other scripting language implementations typically struggle to match this performance level.
The Lua state (Lua VM instance) is shared across all the requests handled by a single nginx worker process to miminize memory use.
On a ThinkPad T400 2.80 GHz laptop, the HelloWorld example readily achieves 28k req/sec using http_load -p 10. By contrast, Nginx + php-fpm 5.2.8 + Unix Domain Socket yields 6k req/sec and Node.js v0.6.1 yields 10.2k req/sec for their HelloWorld equivalents.
This module performs best when built with LuaJIT 2.0.
The module is compatible with the following versions of Nginx:
- 1.1.x (last tested: 1.1.5)
- 1.0.x (last tested: 1.0.11)
- 0.9.x (last tested: 0.9.4)
- 0.8.x >= 0.8.54 (last tested: 0.8.54)
The code repository of this project is hosted on github at chaoslawful/lua-nginx-module.
The ngx_openresty bundle can be used to install Nginx, ngx_lua, either one of the standard Lua 5.1 interpreter or LuaJIT 2.0, as well as a package of powerful companion Nginx modules. The basic installation step is a simple ./configure --with-luajit && make && make install.
Alternatively, ngx_lua can be manually compiled into Nginx:
- Install LuaJIT 2.0 (Recommended) or Lua 5.1 (Lua 5.2 is not supported yet). Lua can be obtained free from the the LuaJIT download page or the standard Lua homepage. Some distribution package managers also distribute Lua and LuaJIT.
- Download the latest version of the ngx_devel_kit (NDK) module HERE.
- Download the latest version of this module HERE.
- Download the latest version of Nginx HERE (See Nginx Compatibility)
Build the source with this module:
wget 'http://nginx.org/download/nginx-1.0.11.tar.gz'
tar -xzvf nginx-1.0.11.tar.gz
cd nginx-1.0.11/
# tell nginx's build system where to find lua:
export LUA_LIB=/path/to/lua/lib
export LUA_INC=/path/to/lua/include
# or tell where to find LuaJIT when if using JIT instead
# export LUAJIT_LIB=/path/to/luajit/lib
# export LUAJIT_INC=/path/to/luajit/include/luajit-2.0
# Here we assume Nginx is to be installed under /opt/nginx/.
./configure --prefix=/opt/nginx \
--add-module=/path/to/ngx_devel_kit \
--add-module=/path/to/lua-nginx-module
make -j2
make install
Please report bugs or submit patches by:
- Creating a ticket on the GitHub Issue Tracker (Recommended)
- Posting to the Nginx Mailing List and also adding
[ngx_lua]to the mail subject.
- implement the
ngx.sleep(time)Lua API. - implement the
ngx.worker.get_pid()Lua API. - implement LuaSocket UDP API in our cosocket API.
- implement the
ngx.re.splitmethod. - use
ngx_hash_tto optimize the built-in header look-up process for ngx.req.set_header, ngx.header.HEADER, and etc. - fix HTTP 1.0 support: we should by default close the current HTTP 1.0 connection right away if no
Content-Lengthresponse header is set. the current automatic full buffering bahvior is way too expensive. - add configure options for different strategies of handling the cosocket connection exceeding in the pools.
- add directives to run Lua codes when nginx stops/reloads.
- deal with TCP 3-second delay problem under great connection harness.
- add support for multi-value arguments to ngx.req.set_uri_args if its
argsargument is a Lua table. - add APIs to access cookies as key/value pairs.
- add
ignore_resp_headers,ignore_resp_body, andignore_respoptions to ngx.location.capture and ngx.location.capture_multi methods, to allow micro performance tuning on the user side.
- add the
lua_requiredirective to load module into main thread's globals. - add Lua code automatic time slicing support by yielding and resuming the Lua VM actively via Lua's debug hooks.
- make set_by_lua, header_filter_by_lua, and their variants use the same mechanism as content_by_lua, rewrite_by_lua, access_by_lua, and their variants.
- add coroutine API back to the Lua user land.
- add
statmode similar to mod_lua.
1 February, 2012
- bugfix: ngx.exit, ngx.redirect, ngx.exec, and ngx.req.set_uri(uri, true) could return (they should never return as per the documentation). this bug had appeared in ngx_lua v0.3.1rc4 and ngx_openresty 1.0.6.13. thanks @cyberty for reporting it.
- bugfix:
ngx_http_lua_header_filter_initwas called with an argument which actually accepts none. this could cause compilation errors at least with gcc 4.3.4 as reported in github issue #80. thanks bigplum (Simon). - bugfix: fixed all the warnings from the clang static analyzer.
- feature: allow use of the
DDEBUGmacro from the outside (via the-D DDEBUG=1C compiler opton).
11 January, 2012
- bugfix: fixed a bug when the both the main request and the subrequest are POST requests with a body: we should not forward the main request's
Content-Lengthheaders to the user subrequests. thanks 朱峰. - feature: implemented the API for reading response headers from within Lua:
value = ngx.header.HEADER, see ngx.header.HEADER. - bugfix: fixed a bug when setting a multi-value response header to a single value (via writing to ngx.header.HEADER): the single value will be repeated on each old value.
- bugfix: fixed an issue in ngx.redirect, ngx.exit, and ngx.exec: these function calls would be intercepted by Lua
pcall/xpcallbecause they used Lua exceptions; now they use Lua yield just as ngx.location.capture. thanks @hugozhu for reporting this. - feature: now we also return the
Last-Modifiedheader (if any) for the subrequest response object. thanks @cyberty and sexybabes. - feature: now ngx.exec supports Lua table as the second args argument value. thanks sexybabes.
- feature: implemented the ngx.headers_sent API to check if response headers are sent (by ngx_lua). thanks @hugozhu.
- feature: exposes the CRC-32 API of the Nginx core to the Lua land, in the form of the ngx.crc32_short and ngx.crc32_long methods. thanks @Lance.
- feature: now for HTTP 1.0 requests, we disable the automatic full buffering mode if the user sets the
Content-Lengthresponse header before sending out the headers. this allows streaming output for HTTP 1.0 requests if the content length can be calculated beforehand. thanks 李子义. - bugfix: now we properly support setting the
Cache-Controlresponse header via the ngx.header.HEADER interface. - bugfix: no longer set header hash to
1. use thengx_hash_key_lcinstead. - bugfix: calling ngx.exec to jump to a named location did not clear the context object of LuaNginxModule properly and might cause evil problems. thanks Nginx User.
- bugfix: now we explicitly clear all the modules' contexts before dump to named location with ngx.exec.
- feature: implemented ngx.req.set_uri and ngx.req.set_uri_args to emulate HttpRewriteModule's rewrite directive. thanks Vladimir Protasov (utros) and Nginx User.
- bugfix: now we skip rewrite phase Lua handlers altogether if HttpRewriteModule's rewrite directive issue a location re-lookup by changing URIs (but not including
rewrite ... break). thanks Nginx User. - feature: added constant
ngx.HTTP_METHOD_NOT_IMPLEMENTED (501). thanks Nginx User. - feature: added new Lua functions ngx.req.read_body, ngx.req.discard_body, ngx.req.get_body_data, and ngx.req.get_body_file. thanks Tzury Bar Yochay for funding the development work.
- bugfix: fixed hanging issues when using ngx.exec within rewrite_by_lua and access_by_lua. thanks Nginx User for reporting it.
- feature: added new Lua API ngx.req.set_body_file. thanks Tzury Bar Yochay for funding the development work.
- feature: added new Lua API ngx.req.set_body_data. thanks Tzury Bar Yochay for funding the development work.
- bugfix: lua_need_request_body should not skip requests with methods other than
POSTandPUT. thanks Nginx User. - bugfix: no longer free request body buffers that are not allocated by ourselves.
- bugfix: now we allow setting ngx.var.VARIABLE to nil.
- feature: added new directive lua_shared_dict.
- feature: added Lua API for the shm-based dictionary, see ngx.shared.DICT.
- bugfix: fixed spots of -Werror=unused-but-set-variable warning issued by gcc 4.6.0.
- bugfix: ndk.set_var.DIRECTIVE had a memory issue and might pass empty argument values to the directive being called. thanks dannynoonan.
- feature: added the
ctxoption to ngx.location.capture: you can now specify a custom Lua table to pass to the subrequest as its ngx.ctx. thanks @hugozhu. - feature: added the ngx.encode_args method to encode a Lua code to a URI query string. thanks 郭颖 (0597虾).
- feature: ngx.location.capture and ngx.exec now supports the same Lua args table format as in ngx.encode_args. thanks 郭颖 (0597虾).
- bugfix:
Cache-Controlheader modification might introduce empty value headers when using with the standard HttpHeadersModule. - feature: added ngx.hmac_sha1. thanks drdrxp.
- docs: documented the long-existent ngx.md5 and ngx.md5_bin APIs.
- docs: massive documentation improvements. thanks Nginx User.
- feature: added new regex options
janddto ngx.re.match, ngx.re.gmatch, ngx.re.sub, and ngx.re.gsub so as to enable the PCRE JIT mode and DFA mode, respectively. thanks @姜大炮 for providing the patch. - feature: added options
copy_all_varsandvarsto ngx.location.capture and ngx.location.capture_multi. thanks Marcus Clyne for the patch. - feature: added new Lua API ngx.now to return the current time (including the milliseconds part as the decimal part). thanks 林青.
- feature: added new Lua API ngx.update_time to forcibly updating Nginx's time cache.
- feature: added
waitboolean argument to ngx.flush to support synchronous flushing:ngx.flush(true)will not return until all the data has been flushed into the system send buffer or the send timeout has expired. - bugfix: now we check timed out downstream connections in our write event handler.
- feature: added constant
ngx.HTTP_GATEWAY_TIMEOUT (504)per Fry-kun in github issue #73. - bugfix: ngx.var.VARIABLE did not evaluate to
nilwhen the Nginx variable'svalidflag is0. - bugfix: there were various places where we did not check the pointer returned by the memory allocator.
- bugfix: ngx.req.set_header and ngx.req.clear_header did not handle the
Accept-Encodingrequest headers properly. thanks 天街夜色. - bugfix: ngx.req.set_header might cause invalid memory reads because Nginx request header values must be
NULLterminated. thanks Maxim Dounin. - bugfix: removing builtin headers via ngx.req.clear_header and its equivalent in huge request headers with 20+ entries could result in data loss. thanks Chris Dumoulin.
- bugfix: ngx.req.get_uri_args and ngx.req.get_post_args now only parse up to
100arguments by default. but one can specify the optional argument to these two methods to specify a custom maximum number of args. thanks Tzury Bar Yochay for reporting this. - bugfix: ngx.req.get_headers now only parse up to
100request headers by default. but one can specify the optional argument to this method to specify a custom maximum number of headers.
September 02, 2011
New features
- added the header_filter_by_lua and header_filter_by_lua_file directives. thanks Liseen Wan (万珣新).
- implemented the PCRE regex API for Lua: ngx.re.match, ngx.re.gmatch, ngx.re.sub, and ngx.re.gsub.
- now we add the
ngxandndktable intopackage.loadedsuch that the user can writelocal ngx = require 'ngx'andlocal ndk = require 'ndk'. thanks @Lance. - added new directive lua_regex_cache_max_entries to control the upper limit of the worker-process-level compiled-regex cache enabled by the
oregex option. - implemented the special ngx.ctx Lua table for user programmers to store per-request Lua context data for their applications. thanks 欧远宁 for suggesting this feature.
- now ngx.print and ngx.say allow (nested) array-like table arguments. the array elements in them will be sent piece by piece. this will avoid string concatenation for templating engines like ltp.
- implemented the ngx.req.get_post_args method for fetching url-encoded POST query arguments from within Lua.
- implemented the ngx.req.get_uri_args method to fetch parsed URL query arguments from within Lua. thanks Bertrand Mansion (golgote).
- added new function ngx.parse_http_time, thanks James Hurst.
- now we allow Lua boolean and
nilvalues in arguments to ngx.say, ngx.print, ngx.log and print. - added support for user C macros
LUA_DEFAULT_PATHandLUA_DEFAULT_CPATH. for now we can only define them inngx_lua'sconfigfile because nginxconfigure's--with-cc-optoption hates values with double-quotes in them. sigh. This feature is used by The ngx_openresty bundle to bundle third party Lua libraries.
Bug fixes
- worked-around the "stack overflow" issue while using
luarocks.loaderand disabling lua_code_cache, as described as github issue #27. thanks Patrick Crosby. - fixed the
zero size buf in outputalert while combining lua_need_request_body on + access_by_lua/rewrite_by_lua + proxy_pass/fastcgi_pass. thanks Liseen Wan (万珣新). - fixed issues with HTTP 1.0 HEAD requests.
- made setting
ngx.header.HEADERafter sending out response headers throw out a Lua exception to help debugging issues like github issue #49. thanks Bill Donahue (ikhoyo). - fixed an issue regarding defining global variables in C header files: we should have defined the global
ngx_http_lua_exceptionin a single compilation unit. thanks @姜大炮.
The following dependencies are required to run the test suite:
-
Nginx version >= 0.8.54
-
Perl modules:
-
Nginx modules:
- echo-nginx-module: http://github.com/agentzh/echo-nginx-module
- drizzle-nginx-module: http://github.com/chaoslawful/drizzle-nginx-module
- rds-json-nginx-module: http://github.com/agentzh/rds-json-nginx-module
- set-misc-nginx-module: http://github.com/agentzh/set-misc-nginx-module
- headers-more-nginx-module: http://github.com/agentzh/headers-more-nginx-module
- memc-nginx-module: http://github.com/agentzh/memc-nginx-module
- srcache-nginx-module: http://github.com/agentzh/srcache-nginx-module
- ngx_auth_request: http://mdounin.ru/hg/ngx_http_auth_request_module/
-
C libraries:
-
Lua modules:
- lua-yajl: https://github.com/brimworks/lua-yajl
- Note: the compiled module has to be placed in '/usr/local/lib/lua/5.1/'
- lua-yajl: https://github.com/brimworks/lua-yajl
-
Applications:
- mysql: create database 'ngx_test', grant all privileges to user 'ngx_test', password is 'ngx_test'
- memcached
The order in which these modules are added during configuration is important as the position of any filter module in the filtering chain determines the final output. The correct adding order is:
- ngx_devel_kit
- set-misc-nginx-module
- ngx_http_auth_request_module
- echo-nginx-module
- memc-nginx-module
- lua-nginx-module (i.e. this module)
- headers-more-nginx-module
- srcache-nginx-module
- drizzle-nginx-module
- rds-json-nginx-module
This module is licensed under the BSD license.
Copyright (C) 2009-2012, by Xiaozhe Wang (chaoslawful) chaoslawful@gmail.com.
Copyright (C) 2009-2012, by Zhang "agentzh" Yichun (章亦春) agentzh@gmail.com.
All rights reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
-
Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
-
Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- lua-resty-memcached library based on ngx_lua cosocket.
- lua-resty-redis library based on ngx_lua cosocket.
- lua-resty-mysql library based on ngx_lua cosocket.
- lua-resty-upload library based on ngx_lua cosocket.
- lua-resty-string library based on LuaJIT FFI.
- Routing requests to different MySQL queries based on URI arguments
- Dynamic Routing Based on Redis and Lua
- Using LuaRocks with ngx_lua
- Introduction to ngx_lua
- ngx_devel_kit
- HttpEchoModule
- HttpDrizzleModule
- postgres-nginx-module
- HttpMemcModule
- The ngx_openresty bundle