Linux中Nginx反向代理之负载均衡实现

一、什么是负载均衡

单个服务器解决不了，我们增加服务器数量，然后将请求分发到各个服务器上，将原先请求集中到单个服务器上的情况改为将请求分发到多个服务器上，将负载分发到不同的服务器上，也就是我们所说的负载均衡。

二、Nginx实现负载均衡

1、实现效果

（1）浏览器地址栏中输入地址 http://123.56.241.139/index/index.html，通过负载均衡，请求平均分配到8080和8081服务端口中。

2、准备工作

（1）Linux系统中准备两台tomcat服务器，一台tomcat服务器端口为8080，一台tomcat服务器端口为8081。

（2）在两台tomcat服务器里面的webapps目录中，分别创建名称是index的文件夹，在index文件夹中分别创建index.html文件，用于测试使用。

（3）将两台tomcat服务器分别启动。

3、在nginx配置文件nginx.conf中进行负载均衡的配置

nginx.conf配置文件

#user  nobody;
worker_processes  1;

#error_log  logs/error.log;
#error_log  logs/error.log  notice;
#error_log  logs/error.log  info;

#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";

    #access_log  logs/access.log  main;

    sendfile        on;
    #tcp_nopush     on;

    #keepalive_timeout  0;
    keepalive_timeout  65;

    #gzip  on;
    upstream myserver {
    	server 123.56.241.139:8080;
        server 123.56.241.139:8081;
    }

    server {
        listen       80;
        server_name  123.56.241.139;

        #charset koi8-r;

        #access_log  logs/host.access.log  main;

        location / {
            proxy_pass http://myserver;
            root   html;
            index  index.html index.htm;
        }

        #error_page  404              /404.html;

        # redirect server error pages to the static page /50x.html
        #
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }

        # proxy the PHP scripts to Apache listening on 127.0.0.1:80
        #
        #location ~ .php$ {
        #    proxy_pass   http://127.0.0.1;
        #}

        # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
        #
        #location ~ .php$ {
        #    root           html;
        #    fastcgi_pass   127.0.0.1:9000;
        #    fastcgi_index  index.php;
        #    fastcgi_param  SCRIPT_FILENAME  /scripts$fastcgi_script_name;
        #    include        fastcgi_params;
        #}

        # deny access to .htaccess files, if Apaches document root
        # concurs with nginxs one
        #
        #location ~ /.ht {
        #    deny  all;
        #}
    }


    # another virtual host using mix of IP-, name-, and port-based configuration
    #
    #server {
    #    listen       8000;
    #    listen       somename:8080;
    #    server_name  somename alias another.alias;

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


    # HTTPS server
    #
    #server {
    #    listen       443 ssl;
    #    server_name  localhost;

    #    ssl_certificate      cert.pem;
    #    ssl_certificate_key  cert.key;

    #    ssl_session_cache    shared:SSL:1m;
    #    ssl_session_timeout  5m;

    #    ssl_ciphers  HIGH:!aNULL:!MD5;
    #    ssl_prefer_server_ciphers  on;

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

}

重启nginx，执行命令：./nginx，然后测试访问