Nginx的简介就不多说了，直接说使用即可，我们用nginx来都是当做服务器来接受客户端的请求，内部转发到应用。这里介绍一下怎么用nginx来搭建负载均衡。

搭建负载均衡

有时候我们有几台服务器，用来缓解服务端的压力，那么此时可以用nginx搭建负载均衡，我这里就直接用端口区分即可，如下，在nginx.conf配置文件的http中加入内容：

server {
        listen       8080;
        server_name  localhost;
        location / {
            root   html;
            index  index8080.html index.htm;
        }
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }
    }
    server {
        listen       8081;
        server_name  localhost;
        location / {
            root   html;
            index  index8081.html index.htm;
        }
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }
    }

当然这里要在html的目录下新建两个html: index8080.html、index8081.html.

然后，在http中再加入如下内容，设置负载均衡，负载均衡策略默认为轮询：

upstream first { 
      server  127.0.0.1:8080; 
      server  127.0.0.1:8081; 
}

最后，修改80请求的策略到负载均衡first:

server {
    listen       80;
    server_name  localhost;
    location / {
        proxy_pass         http://first; 
        proxy_set_header   Host             $host; 
        proxy_set_header   X-Real-IP        $remote_addr; 
        proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for; 
    }
}

重新启动nginx，访问localhost，会发现轮询访问了8080和80801端口，到此负载均衡搭建完毕。

nginx的默认配置文件

这个跟本篇博文无关

#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;
    server {
        listen       80;
        server_name  localhost;
        #charset koi8-r;
        #access_log  logs/host.access.log  main;
        location / {
            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 Apache's document root
        # concurs with nginx's 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;
    #    }
    #}
}