change: default to cache DNS record according to the TTL

Since lua-resty-dns-client provides an internal cache, we don't need to
cache it twice.

Signed-off-by: spacewander <spacewanderlzx@gmail.com>

.travis/apisix_cli_test/test_validate_config.sh

@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+# validate the config.yaml
+
+. ./.travis/apisix_cli_test/common.sh
+
+echo '
+apisix:
+  dns_resolver_valid: "/apisix"
+' > conf/config.yaml
+
+out=$(make init 2>&1 || true)
+if ! echo "$out" | grep 'dns_resolver_valid should be a number'; then
+    echo "failed: dns_resolver_valid should be a number"
+    exit 1
+fi
+
+echo "passed: dns_resolver_valid should be a number"

apisix/cli/ngx_tpl.lua

@@ -65,7 +65,7 @@ stream {
 
     lua_shared_dict lrucache-lock-stream   10m;
 
-    resolver {% for _, dns_addr in ipairs(dns_resolver or {}) do %} {*dns_addr*} {% end %} valid={*dns_resolver_valid*};
+    resolver {% for _, dns_addr in ipairs(dns_resolver or {}) do %} {*dns_addr*} {% end %} {% if dns_resolver_valid then %}valid={*dns_resolver_valid*}{% end %};
     resolver_timeout {*resolver_timeout*};
 
     # stream configuration snippet starts
@@ -187,7 +187,7 @@ http {
 
     lua_socket_log_errors off;
 
-    resolver {% for _, dns_addr in ipairs(dns_resolver or {}) do %} {*dns_addr*} {% end %} valid={*dns_resolver_valid*};
+    resolver {% for _, dns_addr in ipairs(dns_resolver or {}) do %} {*dns_addr*} {% end %} {% if dns_resolver_valid then %}valid={*dns_resolver_valid*}{% end %};
     resolver_timeout {*resolver_timeout*};
 
     lua_http10_buffering off;

apisix/cli/ops.lua

@@ -279,6 +279,12 @@ Please modify "admin_key" in conf/config.yaml .
         end
     end
 
+    if yaml_conf.apisix.dns_resolver_valid then
+        if tonumber(yaml_conf.apisix.dns_resolver_valid) == nil then
+            util.die("apisix->dns_resolver_valid should be a number")
+        end
+    end
+
     -- Using template.render
     local sys_conf = {
         use_or_1_15 = use_or_1_15,

apisix/core/utils.lua

@@ -14,6 +14,7 @@
 -- See the License for the specific language governing permissions and
 -- limitations under the License.
 --
+local config_local   = require("apisix.core.config_local")
 local core_str       = require("apisix.core.string")
 local table          = require("apisix.core.table")
 local json           = require("apisix.core.json")
@@ -85,11 +86,16 @@ end
 
 local function dns_parse(domain)
     if dns_resolvers ~= current_inited_resolvers then
+        local local_conf = config_local.local_conf()
+        local valid = table.try_read_attr(local_conf, "apisix", "dns_resolver_valid")
+
         local opts = {
             ipv6 = true,
             nameservers = table.clone(dns_resolvers),
             retrans = 5,  -- 5 retransmissions on receive timeout
             timeout = 2000,  -- 2 sec
+            order = {"last", "A", "AAAA", "CNAME"}, -- avoid querying SRV (we don't support it yet)
+            validTtl = valid,
         }
         local ok, err = dns_client.init(opts)
         if not ok then

apisix/init.lua

@@ -47,7 +47,6 @@ end
 local load_balancer
 local local_conf
 local dns_resolver
-local lru_resolved_domain
 local ver_header    = "APISIX/" .. core.version.VERSION
 
 
@@ -121,12 +120,6 @@ function _M.http_init_worker()
     require("apisix.upstream").init_worker()
 
     local_conf = core.config.local_conf()
-    local dns_resolver_valid = local_conf and local_conf.apisix and
-                        local_conf.apisix.dns_resolver_valid
-
-    lru_resolved_domain = core.lrucache.new({
-        ttl = dns_resolver_valid, count = 512, invalid_stale = true,
-    })
 
     if local_conf.apisix and local_conf.apisix.enable_server_tokens == false then
         ver_header = "APISIX"
@@ -420,16 +413,8 @@ function _M.http_access_phase()
             end
 
             if upstream.has_domain then
-                -- try to fetch the resolved domain, if we got `nil`,
-                -- it means we need to create the cache by handle.
-                -- the `api_ctx.conf_version` is different after we called
-                -- `parse_domain_in_up`, need to recreate the cache by new
-                -- `api_ctx.conf_version`
                 local err
-                upstream, err = lru_resolved_domain(upstream,
-                                                    upstream.modifiedIndex,
-                                                    parse_domain_in_up,
-                                                    upstream)
+                upstream, err = parse_domain_in_up(upstream)
                 if err then
                     core.log.error("failed to get resolved upstream: ", err)
                     return core.response.exit(500)
@@ -454,8 +439,7 @@ function _M.http_access_phase()
     else
         if route.has_domain then
             local err
-            route, err = lru_resolved_domain(route, api_ctx.conf_version,
-                                             parse_domain_in_route, route)
+            route, err = parse_domain_in_route(route)
             if err then
                 core.log.error("failed to get resolved route: ", err)
                 return core.response.exit(500)
@@ -806,12 +790,6 @@ function _M.stream_init_worker()
     load_balancer = require("apisix.balancer").run
 
     local_conf = core.config.local_conf()
-    local dns_resolver_valid = local_conf and local_conf.apisix and
-                        local_conf.apisix.dns_resolver_valid
-
-    lru_resolved_domain = core.lrucache.new({
-        ttl = dns_resolver_valid, count = 512, invalid_stale = true,
-    })
 end
 
 

conf/config-default.yaml

@@ -106,7 +106,7 @@ apisix:
   # dns_resolver:                 # If not set, read from `/etc/resolv.conf`
   #  - 1.1.1.1
   #  - 8.8.8.8
-  dns_resolver_valid: 30          # valid time for dns result 30 seconds
+  # dns_resolver_valid: 30        # if given, override the TTL of the valid records. The unit is second.
   resolver_timeout: 5             # resolver timeout
   ssl:
     enable: true

t/coredns/db.test.local

@@ -11,3 +11,6 @@ $ORIGIN test.local.
     3600 IN NS b.iana-servers.net.
 
 ipv6     IN AAAA  ::1
+
+ttl 300  IN A     127.0.0.1
+ttl.1s 1  IN A     127.0.0.1

t/node/upstream-domain-with-special-dns.t

@@ -69,3 +69,165 @@ upstreams:
 GET /hello
 --- response_body
 hello world
+
+
+
+=== TEST 2: default ttl
+--- log_level: debug
+--- apisix_yaml
+upstreams:
+    -
+    id: 1
+    nodes:
+        ttl.test.local:1980: 1
+    type: roundrobin
+--- config
+    location /t {
+        content_by_lua_block {
+            local http = require "resty.http"
+            local uri = "http://127.0.0.1:" .. ngx.var.server_port .. "/hello"
+            for i = 1, 3 do
+                local httpc = http.new()
+                local res, err = httpc:request_uri(uri, {method = "GET"})
+                if not res or res.body ~= "hello world\n" then
+                    ngx.say(err)
+                    return
+                end
+            end
+        }
+    }
+--- request
+GET /t
+--- error_log
+"ttl":300
+--- grep_error_log eval
+qr/connect to 127.0.0.1:1053/
+--- grep_error_log_out
+connect to 127.0.0.1:1053
+
+
+
+=== TEST 3: override ttl
+--- log_level: debug
+--- yaml_config
+apisix:
+    node_listen: 1984
+    config_center: yaml
+    enable_admin: false
+    dns_resolver_valid: 900
+--- apisix_yaml
+upstreams:
+    -
+    id: 1
+    nodes:
+        ttl.test.local:1980: 1
+    type: roundrobin
+--- config
+    location /t {
+        content_by_lua_block {
+            local http = require "resty.http"
+            local uri = "http://127.0.0.1:" .. ngx.var.server_port .. "/hello"
+            for i = 1, 3 do
+                local httpc = http.new()
+                local res, err = httpc:request_uri(uri, {method = "GET"})
+                if not res or res.body ~= "hello world\n" then
+                    ngx.say(err)
+                    return
+                end
+            end
+        }
+    }
+--- request
+GET /t
+--- grep_error_log eval
+qr/connect to 127.0.0.1:1053/
+--- grep_error_log_out
+connect to 127.0.0.1:1053
+--- error_log
+"ttl":900
+
+
+
+=== TEST 4: cache expire
+--- log_level: debug
+--- apisix_yaml
+upstreams:
+    -
+    id: 1
+    nodes:
+        ttl.1s.test.local:1980: 1
+    type: roundrobin
+--- config
+    location /t {
+        content_by_lua_block {
+            local http = require "resty.http"
+            local uri = "http://127.0.0.1:" .. ngx.var.server_port .. "/hello"
+            for i = 1, 2 do
+                for j = 1, 3 do
+                    local httpc = http.new()
+                    local res, err = httpc:request_uri(uri, {method = "GET"})
+                    if not res or res.body ~= "hello world\n" then
+                        ngx.say(err)
+                        return
+                    end
+                end
+
+                if i < 2 then
+                    ngx.sleep(1.1)
+                end
+            end
+        }
+    }
+--- request
+GET /t
+--- grep_error_log eval
+qr/connect to 127.0.0.1:1053/
+--- grep_error_log_out
+connect to 127.0.0.1:1053
+connect to 127.0.0.1:1053
+
+
+
+=== TEST 5: cache expire (override ttl)
+--- log_level: debug
+--- yaml_config
+apisix:
+    node_listen: 1984
+    config_center: yaml
+    enable_admin: false
+    dns_resolver_valid: 1
+--- apisix_yaml
+upstreams:
+    -
+    id: 1
+    nodes:
+        ttl.test.local:1980: 1
+    type: roundrobin
+--- config
+    location /t {
+        content_by_lua_block {
+            local http = require "resty.http"
+            local uri = "http://127.0.0.1:" .. ngx.var.server_port .. "/hello"
+            for i = 1, 2 do
+                for j = 1, 3 do
+                    local httpc = http.new()
+                    local res, err = httpc:request_uri(uri, {method = "GET"})
+                    if not res or res.body ~= "hello world\n" then
+                        ngx.say(err)
+                        return
+                    end
+                end
+
+                if i < 2 then
+                    ngx.sleep(1.1)
+                end
+            end
+        }
+    }
+--- request
+GET /t
+--- grep_error_log eval
+qr/connect to 127.0.0.1:1053/
+--- grep_error_log_out
+connect to 127.0.0.1:1053
+connect to 127.0.0.1:1053