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Openresty-Lua动态修改upstream后端服务

nginx.conf 配置文件

worker_processes  1;
pid        logs/nginx.pid;
events {
  worker_connections  1024;
}

http {
  include       mime.types;
  default_type  application/octet-stream;

  log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                  '$status $body_bytes_sent "$http_referer" '
                  '"$http_user_agent" "$http_x_forwarded_for"';
  sendfile        on;

  keepalive_timeout  65;

  lua_shared_dict upstreams 1m;  # 声明一个ngx多进程全局共享内存区域，_G 作为基于shm的Lua字典的存储空间ngx.shared.   
  upstream default_upstream {                        # 配置后端服务器组
              server 127.0.0.1:8081;
              server 127.0.0.1:8082;
  }

  upstream lua_upstream {                        # 配置后端服务器组
              server 127.0.0.1:8084;
              server 127.0.0.1:8083;
  }

  server {
      listen       80;
      server_name  localhost;

      access_log  logs/80.access.log  main;
      error_log   logs/80.error.log error;

      location = /_switch_upstream {
           content_by_lua_block{
                  local ups = ngx.req.get_uri_args()["upstream"]
                  if ups == nil or ups == "" then
                      ngx.say("upstream is nil 1")
                      return nil
                  end
                  local host = ngx.var.http_host
                  local upstreams = ngx.shared.upstreams
                  local ups_src = upstreams:get(host)
                  ngx.say("Current upstream is :",ups_src)
                  ngx.log(ngx.WARN, host, " change upstream from ", ups_src, " to ", ups)
                  local succ, err, forcible = upstreams:set(host,  ups)
                  ngx.say(host, " change upstream from ", ups_src, " to ", ups)
          }
      }

      location / {
          set_by_lua_block $my_upstream {
              local ups = ngx.shared.upstreams:get(ngx.var.http_host)
              if ups ~= nil then
                  ngx.log(ngx.ERR, "get [", ups,"] from ngx.shared")
                  return ups
              end
              return "default_upstream"
          }

          proxy_next_upstream off;
          proxy_set_header    X-Real-IP           $remote_addr;
          proxy_set_header    X-Forwarded-For     $proxy_add_x_forwarded_for;
          proxy_set_header    Host                $host;
          proxy_http_version  1.1;
          proxy_set_header    Connection  "";
          proxy_pass          http://$my_upstream ;
      }
  }   

  server {
      listen       8081;
      server_name  localhost;

      location / {
          root   html81;
          index  index.html index.htm;
      }
  }

  server {
      listen       8082;
      server_name  localhost;

      location / {
          root   html82;
          index  index.html index.htm;
      }
  }

  server {
      listen       8083;
      server_name  localhost;

      location / {
          root   html83;
          index  index.html index.htm;
      }
  }

  server {
      listen       8084;
      server_name  localhost;

      location / {
          root   html84;
          index  index.html index.htm;
      }
  }
}

4个端口分别对应4个html 根目录
- html81/index.html 内容 server name 8081
- html82/index.html 内容 server name 8082
- html83/index.html 内容 server name 8083
- html84/index.html 内容 server name 8084

如何切换后端upstream

default_upstream 切换到 lua_upstream

root@tinywan:# curl http://127.0.0.1/_switch_upstream?upstream=lua_upstream
127.0.0.1 change upstream from default_upstream to lua_upstream

lua_upstream 切换（还原default_upstream）到 default_upstream

root@tinywan:# curl http://127.0.0.1/_switch_upstream?upstream=default_upstream
127.0.0.1 change upstream from lua_upstream to default_upstream

一个收集upstream_response_time的平均数据的例子

lua_shared_dict log_dict 5M  # 声明一个ngx多进程全局共享内存区域

server{
  location / {
      proxy_pass http;//mybackend   # 代理模块
      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("upsteam_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
      '
  }
}

动态修改upstream后端服务和upstream_response_time的平均数据合并后的代码

#user  nobody;
worker_processes  1;
pid        logs/nginx.pid;
events {
   worker_connections  1024;
}

http {
   include       mime.types;
   default_type  application/octet-stream;

   log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                   '$status $body_bytes_sent "$http_referer" '
                   '"$http_user_agent" "$http_x_forwarded_for"';
   sendfile        on;

   keepalive_timeout  65;

lua_shared_dict upstreams 1m;  # ngx多进程全局共享内存，保存upstream值   
upstream default_upstream {                        # 配置后端服务器组
           server 127.0.0.1:8081;
           server 127.0.0.1:8082;
}

upstream lua_upstream {                        # 配置后端服务器组
           server 127.0.0.1:8084;
           server 127.0.0.1:8083;
}

server {
   listen       80;
   server_name  localhost;

   access_log  logs/80.access.log  main;
   error_log   logs/80.error.log error;

   location = /_switch_upstream {
           default_type 'text/html';
           content_by_lua_block{
                   local ups = ngx.req.get_uri_args()["upstream"]
                   if ups == nil or ups == "" then
                       ngx.say("upstream is nil 1")
           return nil
                   end
                   local host = ngx.var.http_host
           local upstreams = ngx.shared.upstreams
                   local ups_src = upstreams:get(host)
           ngx.say("Current upstream is :",ups_src)
                   ngx.log(ngx.WARN, host, " change upstream from ", ups_src, " to ", ups)
                   local succ, err, forcible = upstreams:set(host,  ups)
                   ngx.say(host, " change upstream from ", ups_src, " to ", ups)
           }
   }

   #location ~ (^/api/|^/p/|^/m/|^/oauthapi/) {
   location / {
       set_by_lua_block $my_upstream {
       local ups = ngx.shared.upstreams:get(ngx.var.http_host)
       if ups ~= nil then
           ngx.log(ngx.ERR, "get [", ups,"] from ngx.shared")
           return ups
       end
       return "default_upstream"
       }

       proxy_next_upstream off;
       proxy_set_header    X-Real-IP           $remote_addr;
       proxy_set_header    X-Forwarded-For     $proxy_add_x_forwarded_for;
       proxy_set_header    Host                $host;
       proxy_http_version  1.1;
       proxy_set_header    Connection  "";
       proxy_pass          http://$my_upstream ;

       log_by_lua_block {
           local log_dict = ngx.shared.upstreams
               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 {
       default_type 'text/html';  -- 通过浏览器可访问
       content_by_lua_block {
           local log_dict = ngx.shared.upstreams
           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
       }
   }

}   

server {
       listen       8099;
       server_name  localhost;

       #charset koi8-r;

       access_log  logs/80.access.log  main;
   error_log   logs/80.error.log error;
       location / {
       #proxy_pass http://live_node;
       }

       error_page   500 502 503 504  /50x.html;
       location = /50x.html {
           root   html;
       }
   }

   server {
       listen       8081;
       server_name  localhost;

       location / {
           root   html81;
           index  index.html index.htm;
       }
   }

   server {
       listen       8082;
       server_name  localhost;

       location / {
           root   html82;
           index  index.html index.htm;
       }
   }

   server {
       listen       8083;
       server_name  localhost;

       location / {
           root   html83;
           index  index.html index.htm;
       }
   }

server {
       listen       8084;
       server_name  localhost;

       location / {
           root   html84;
           index  index.html index.htm;
       }
   }
}

测试结果：

root@tinywan:/opt/openresty/nginx/conf# curl http://127.0.0.1/status
average upstream response time: 0.0003953488372093 (129 reqs)

浏览器测试，记得加上这个default_type 'text/html';,在浏览器地址栏直接输入即可访问
http://127.0.0.1/_switch_upstream?upstream=default_upstream
HELP:http://chattool.sinaapp.com/?p=2372

Openresty-Lua动态修改upstream后端服务

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