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.<name>   
    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
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