log_by_lua.md

log_by_lua

语法: log_by_lua <lua-script-str>

环境: http, server, location, location if

阶段: log

在 log 请求处理阶段执行内嵌在<lua-script-str>的 Lua 代码。它不替代当前access的日志，而是在其后执行。

注意，当前环境中以下 API 函数当前是被禁用的：

• 输出API函数类（例如：ngx.say 和 ngx.send_headers）
• 控制API函数类（例如：ngx.exit 和 ngx.exec）
• 子请求函数类（例如：ngx.location.capture 和 ngx.location.capture_multi）
• cosocket 函数类（例如：ngx.socket.tcp 和 ngx.req.socket）

这是一个收集 $upstream_response_time 平均处理的例子：

 lua_shared_dict log_dict 5M;

 server {
     location / {
         proxy_pass http://mybackend;

         log_by_lua '
             local log_dict = ngx.shared.log_dict
             local upstream_time = tonumber(ngx.var.upstream_response_time)

             local sum = log_dict:get("upstream_time-sum") or 0
             sum = sum + upstream_time
             log_dict:set("upstream_time-sum", sum)

             local newval, err = log_dict:incr("upstream_time-nb", 1)
             if not newval and err == "not found" then
                 log_dict:add("upstream_time-nb", 0)
                 log_dict:incr("upstream_time-nb", 1)
             end
         ';
     }

     location = /status {
         content_by_lua '
             local log_dict = ngx.shared.log_dict
             local sum = log_dict:get("upstream_time-sum")
             local nb = log_dict:get("upstream_time-nb")

             if nb and sum then
                 ngx.say("average upstream response time: ", sum / nb,
                         " (", nb, " reqs)")
             else
                 ngx.say("no data yet")
             end
         ';
     }
 }

该指令在v0.5.0rc31版本被首次引入。

返回目录

English source:

log_by_lua

syntax: log_by_lua <lua-script-str>

context: http, server, location, location if

phase: log

Run the Lua source code inlined as the <lua-script-str> at the log request processing phase. This does not replace the current access logs, but runs after.

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)
• Cosocket API functions (e.g., ngx.socket.tcp and ngx.req.socket).

Here is an example of gathering average data for $upstream_response_time:

 lua_shared_dict log_dict 5M;

 server {
     location / {
         proxy_pass http://mybackend;

         log_by_lua '
             local log_dict = ngx.shared.log_dict
             local upstream_time = tonumber(ngx.var.upstream_response_time)

             local sum = log_dict:get("upstream_time-sum") or 0
             sum = sum + upstream_time
             log_dict:set("upstream_time-sum", sum)

             local newval, err = log_dict:incr("upstream_time-nb", 1)
             if not newval and err == "not found" then
                 log_dict:add("upstream_time-nb", 0)
                 log_dict:incr("upstream_time-nb", 1)
             end
         ';
     }

     location = /status {
         content_by_lua '
             local log_dict = ngx.shared.log_dict
             local sum = log_dict:get("upstream_time-sum")
             local nb = log_dict:get("upstream_time-nb")

             if nb and sum then
                 ngx.say("average upstream response time: ", sum / nb,
                         " (", nb, " reqs)")
             else
                 ngx.say("no data yet")
             end
         ';
     }
 }

This directive was first introduced in the v0.5.0rc31 release.

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