feat(dbless) use LMDB as DB-less backend

This PR adds LMDB (Lightning Memory-Mapped Database) support for
DB-less. At the same time, the shdict based DB-less storage backend has
been retired and removed from the codebase.

LMDB has better concurrency characters and is generally much more stable
than shdict for storing config data. Because it can be natively accessed
from different processes, we also removed the hack that sends the full
DB-less config to the stream subsystem, which should improve the
stability of DB-less reload at runtime as well.

New config options `lmdb_environment_path` and `lmdb_map_size` has been
added.

Co-authored-by: Suika <xumin.zhou@konghq.com>

.ci/setup_env_github.sh

@@ -9,6 +9,7 @@ OPENRESTY=$(dep_version RESTY_VERSION)
 LUAROCKS=$(dep_version RESTY_LUAROCKS_VERSION)
 OPENSSL=$(dep_version RESTY_OPENSSL_VERSION)
 PCRE=$(dep_version RESTY_PCRE_VERSION)
+RESTY_LMDB=$(dep_version RESTY_LMDB_VERSION)
 
 
 #---------
@@ -32,6 +33,7 @@ kong-ngx-build \
     --kong-nginx-module $KONG_NGINX_MODULE_BRANCH \
     --luarocks $LUAROCKS \
     --openssl $OPENSSL \
+    --resty-lmdb $RESTY_LMDB \
     --pcre $PCRE \
     --debug
 

.requirements

@@ -6,6 +6,7 @@ RESTY_VERSION=1.19.9.1
 RESTY_LUAROCKS_VERSION=3.8.0
 RESTY_OPENSSL_VERSION=1.1.1n
 RESTY_PCRE_VERSION=8.45
+RESTY_LMDB_VERSION=master
 LIBYAML_VERSION=0.2.5
 KONG_BUILD_TOOLS_VERSION=4.25.3
 KONG_NGINX_MODULE_BRANCH=0.2.1

kong-2.8.0-0.rockspec

@@ -167,6 +167,7 @@ build = {
     ["kong.db.dao.vaults"] = "kong/db/dao/vaults.lua",
     ["kong.db.dao.workspaces"] = "kong/db/dao/workspaces.lua",
     ["kong.db.declarative"] = "kong/db/declarative/init.lua",
+    ["kong.db.declarative.marshaller"] = "kong/db/declarative/marshaller.lua",
     ["kong.db.schema"] = "kong/db/schema/init.lua",
     ["kong.db.schema.entities.consumers"] = "kong/db/schema/entities/consumers.lua",
     ["kong.db.schema.entities.routes"] = "kong/db/schema/entities/routes.lua",

kong/api/routes/config.lua

@@ -118,10 +118,11 @@ return {
           })
         end
 
-        if err == "no memory" then
-          kong.log.err("not enough cache space for declarative config")
+        if err == "map full" then
+          kong.log.err("not enough space for declarative config")
           return kong.response.exit(413, {
-            message = "Configuration does not fit in Kong cache"
+            message = "Configuration does not fit in LMDB database, " ..
+                      "consider raising the \"lmdb_map_size\" config for Kong"
           })
         end
 

kong/conf_loader/init.lua

@@ -657,6 +657,9 @@ local CONF_INFERENCES = {
   untrusted_lua = { enum = { "on", "off", "sandbox" } },
   untrusted_lua_sandbox_requires = { typ = "array" },
   untrusted_lua_sandbox_environment = { typ = "array" },
+
+  lmdb_environment_path = { typ = "string" },
+  lmdb_map_size = { typ = "string" },
 }
 
 

kong/constants.lua

@@ -184,7 +184,6 @@ local constants = {
   PROTOCOLS = protocols,
   PROTOCOLS_WITH_SUBSYSTEM = protocols_with_subsystem,
 
-  DECLARATIVE_PAGE_KEY = "declarative:page",
   DECLARATIVE_LOAD_KEY = "declarative_config:loaded",
   DECLARATIVE_HASH_KEY = "declarative_config:hash",
   DECLARATIVE_EMPTY_CONFIG_HASH = string.rep("0", 32),