Nginx之负载均衡

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概要：

随着公司项目越来越大，流量也跟着越来越大，为了避免发生单点故障和系统的高性能，越来越多的网站架构都使用了负载均衡技术，这里简单记录一下Nginx负载均衡的配置方式。

什么是负载均衡

负载均衡是由多台服务器以对称的方式组成一个服务器集合，每台服务器都具有等价的地位，都可以单独对外提供服务而无须其他服务器的辅助。通过某种负载分担技术，将外部发送来的请求均匀分配到对称结构中的某一台服务器上，而接收到请求的服务器独立地回应客户的请求。均衡负载能够平均分配客户请求到服务器列阵，籍此提供快速获取重要数据，解决大量并发访问服务问题。这种群集技术可以用最少的投资获得接近于大型主机的性能。

Nginx配置
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user  www; #使用www用户
worker_processes  4;

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;
    
    #负载均衡池，使用ip_hash保持会话的一致性
     upstream jar_pool{
         ip_hash;
         server 192.168.11.9:8080;
         server 192.168.11.10:8080;
    }


    #监听本地80端口
    server {
        listen       80;
        server_name  localhost;

        #charset koi8-r;

        #access_log  logs/host.access.log  main;

        #location / {
        #    root   html;
        #    index  index.html index.htm;
        # }
      #把所有转发到后端的负载均衡池
        location / {
        proxy_set_header Host $host:$server_port;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_pass http://jar_pool;
    }


        #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;
    #    }
    #}

}