feat: support _meta.pre_function to execute custom logic before execution of each phase (#11793)

Author: Revolyssup

apisix/plugin.lua

@@ -34,6 +34,9 @@ local type          = type
 local local_plugins = core.table.new(32, 0)
 local tostring      = tostring
 local error         = error
+-- make linter happy to avoid error: getting the Lua global "load"
+-- luacheck: globals load, ignore lua_load
+local lua_load          = load
 local is_http       = ngx.config.subsystem == "http"
 local local_plugins_hash    = core.table.new(0, 32)
 local stream_local_plugins  = core.table.new(32, 0)
@@ -49,6 +52,9 @@ local merged_stream_route = core.lrucache.new({
 local expr_lrucache = core.lrucache.new({
     ttl = 300, count = 512
 })
+local meta_pre_func_load_lrucache = core.lrucache.new({
+    ttl = 300, count = 512
+})
 local local_conf
 local check_plugin_metadata
 
@@ -906,10 +912,23 @@ local function check_single_plugin_schema(name, plugin_conf, schema_type, skip_d
                 .. name .. " err: " .. err
         end
 
-        if plugin_conf._meta and plugin_conf._meta.filter then
-            ok, err = expr.new(plugin_conf._meta.filter)
-            if not ok then
-                return nil, "failed to validate the 'vars' expression: " .. err
+        if plugin_conf._meta then
+            if plugin_conf._meta.filter then
+                ok, err = expr.new(plugin_conf._meta.filter)
+                if not ok then
+                    return nil, "failed to validate the 'vars' expression: " .. err
+                end
+            end
+
+            if plugin_conf._meta.pre_function then
+                local pre_function, err = meta_pre_func_load_lrucache(plugin_conf._meta.pre_function
+                                          , "",
+                                          lua_load,
+                                          plugin_conf._meta.pre_function, "meta pre_function")
+                if not pre_function then
+                    return nil, "failed to load _meta.pre_function in plugin " .. name .. ": "
+                                 .. err
+                end
             end
         end
     end
@@ -1130,6 +1149,17 @@ function _M.stream_plugin_checker(item, in_cp)
     return true
 end
 
+local function run_meta_pre_function(conf, api_ctx, name)
+    if conf._meta and conf._meta.pre_function then
+        local _, pre_function = pcall(meta_pre_func_load_lrucache(conf._meta.pre_function, "",
+                                lua_load,
+                                conf._meta.pre_function, "meta pre_function"))
+        local ok, err = pcall(pre_function, conf, api_ctx)
+        if not ok then
+            core.log.error("pre_function execution for plugin ", name, " failed: ", err)
+        end
+    end
+end
 
 function _M.run_plugin(phase, plugins, api_ctx)
     local plugin_run = false
@@ -1169,6 +1199,7 @@ function _M.run_plugin(phase, plugins, api_ctx)
                     goto CONTINUE
                 end
 
+                run_meta_pre_function(conf, api_ctx, plugins[i]["name"])
                 plugin_run = true
                 api_ctx._plugin_name = plugins[i]["name"]
                 local code, body = phase_func(conf, api_ctx)
@@ -1207,6 +1238,7 @@ function _M.run_plugin(phase, plugins, api_ctx)
         local conf = plugins[i + 1]
         if phase_func and meta_filter(api_ctx, plugins[i]["name"], conf) then
             plugin_run = true
+            run_meta_pre_function(conf, api_ctx, plugins[i]["name"])
             api_ctx._plugin_name = plugins[i]["name"]
             phase_func(conf, api_ctx)
             api_ctx._plugin_name = nil

apisix/plugins/example-plugin.lua

@@ -107,6 +107,10 @@ function _M.access(conf, ctx)
     return
 end
 
+function _M.header_filter(conf, ctx)
+    core.log.warn("plugin header_filter phase, conf: ", core.json.encode(conf))
+end
+
 
 function _M.body_filter(conf, ctx)
     core.log.warn("plugin body_filter phase, eof: ", ngx.arg[2],
@@ -119,6 +123,10 @@ function _M.delayed_body_filter(conf, ctx)
                   ", conf: ", core.json.encode(conf))
 end
 
+function _M.log(conf, ctx)
+    core.log.warn("plugin log phase, conf: ", core.json.encode(conf))
+end
+
 
 local function hello()
     local args = ngx.req.get_uri_args()

apisix/schema_def.lua

@@ -1032,8 +1032,15 @@ _M.plugin_injected_schema = {
                 description = "filter determines whether the plugin "..
                                 "needs to be executed at runtime",
                 type  = "array",
-            }
-        }
+            },
+            pre_function = {
+                description = "function to be executed in each phase " ..
+                              "before execution of plugins. The pre_function will have access " ..
+                              "to two arguments: `conf` and `ctx`.",
+                type = "string",
+            },
+        },
+        additionalProperties = false,
     }
 }
 

t/admin/plugins.t

@@ -281,7 +281,7 @@ plugins:
         }
     }
 --- response_body eval
-qr/\{"metadata_schema":\{"properties":\{"ikey":\{"minimum":0,"type":"number"\},"skey":\{"type":"string"\}\},"required":\["ikey","skey"\],"type":"object"\},"priority":0,"schema":\{"\$comment":"this is a mark for our injected plugin schema","properties":\{"_meta":\{"properties":\{"disable":\{"type":"boolean"\},"error_response":\{"oneOf":\[\{"type":"string"\},\{"type":"object"\}\]\},"filter":\{"description":"filter determines whether the plugin needs to be executed at runtime","type":"array"\},"priority":\{"description":"priority of plugins by customized order","type":"integer"\}\},"type":"object"\},"i":\{"minimum":0,"type":"number"\},"ip":\{"type":"string"\},"port":\{"type":"integer"\},"s":\{"type":"string"\},"t":\{"minItems":1,"type":"array"\}\},"required":\["i"\],"type":"object"\},"version":0.1\}/
+qr/\{"metadata_schema":\{"properties":\{"ikey":\{"minimum":0,"type":"number"\},"skey":\{"type":"string"\}\},"required":\["ikey","skey"\],"type":"object"\},"priority":0,"schema":\{"\$comment":"this is a mark for our injected plugin schema","properties":\{"_meta":\{"additionalProperties":false,"properties":\{"disable":\{"type":"boolean"\},"error_response":\{"oneOf":\[\{"type":"string"\},\{"type":"object"\}\]\},"filter":\{"description":"filter determines whether the plugin needs to be executed at runtime","type":"array"\},"pre_function":\{"description":"function to be executed in each phase before execution of plugins. The pre_function will have access to two arguments: `conf` and `ctx`.","type":"string"\},"priority":\{"description":"priority of plugins by customized order","type":"integer"\}\},"type":"object"\},"i":\{"minimum":0,"type":"number"\},"ip":\{"type":"string"\},"port":\{"type":"integer"\},"s":\{"type":"string"\},"t":\{"minItems":1,"type":"array"\}\},"required":\["i"\],"type":"object"\},"version":0.1\}/
 
 
 
@@ -382,7 +382,7 @@ qr/\{"encrypt_fields":\["password"\],"properties":\{"password":\{"type":"string"
         }
     }
 --- response_body
-{"priority":1003,"schema":{"$comment":"this is a mark for our injected plugin schema","properties":{"_meta":{"properties":{"disable":{"type":"boolean"},"error_response":{"oneOf":[{"type":"string"},{"type":"object"}]},"filter":{"description":"filter determines whether the plugin needs to be executed at runtime","type":"array"},"priority":{"description":"priority of plugins by customized order","type":"integer"}},"type":"object"},"burst":{"minimum":0,"type":"integer"},"conn":{"exclusiveMinimum":0,"type":"integer"},"default_conn_delay":{"exclusiveMinimum":0,"type":"number"},"key":{"type":"string"},"key_type":{"default":"var","enum":["var","var_combination"],"type":"string"},"only_use_default_delay":{"default":false,"type":"boolean"}},"required":["conn","burst","default_conn_delay","key"],"type":"object"},"version":0.1}
+{"priority":1003,"schema":{"$comment":"this is a mark for our injected plugin schema","properties":{"_meta":{"additionalProperties":false,"properties":{"disable":{"type":"boolean"},"error_response":{"oneOf":[{"type":"string"},{"type":"object"}]},"filter":{"description":"filter determines whether the plugin needs to be executed at runtime","type":"array"},"pre_function":{"description":"function to be executed in each phase before execution of plugins. The pre_function will have access to two arguments: `conf` and `ctx`.","type":"string"},"priority":{"description":"priority of plugins by customized order","type":"integer"}},"type":"object"},"burst":{"minimum":0,"type":"integer"},"conn":{"exclusiveMinimum":0,"type":"integer"},"default_conn_delay":{"exclusiveMinimum":0,"type":"number"},"key":{"type":"string"},"key_type":{"default":"var","enum":["var","var_combination"],"type":"string"},"only_use_default_delay":{"default":false,"type":"boolean"}},"required":["conn","burst","default_conn_delay","key"],"type":"object"},"version":0.1}