服务器 - nginx优化 - Nginx 负载均衡由理论到实践

通过Nginx实现负载均衡

通过Nginx实现负载均衡

一、概述

二、安装与配置Nginx

三、配置负载均衡

四、负载均衡调度策略

五、实现SSL

一、概述

Nginx负载均衡的应用很广，很多场景下都在使用这种架构。

环境如下：

192.168.1.100 (master node)  server1
192.168.1.109 (slave)        server2
192.168.1.106 (slave)        server3

二、安装与配置Nginx

安装nginx 在上面三台服务器上，分别安装nginx yum install nginx
配置nginx

在上面三台服务器上，分别配置nginx

  user  nginx;
  worker_processes  1;
  error_log  /var/log/nginx_error.log crit;

  worker_rlimit_nofile  8192;

  events {
  worker_connections  1024;
  # you might need to increase this setting for busy servers
  use epoll;
  #  Linux kernels 2.6.x change to epoll
  }

  http {
  server_names_hash_max_size 2048;
  server_names_hash_bucket_size 512;

  server_tokens off;

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

  sendfile on;
  tcp_nopush on;
  tcp_nodelay on;
  keepalive_timeout  10;

  # Gzip on
  gzip on;
  gzip_min_length  1100;
  gzip_buffers  4 32k;
  gzip_types    text/plain application/x-javascript text/xml text/css;

  ignore_invalid_headers on;
  client_max_body_size    8m;
  client_header_timeout  3m;
  client_body_timeout 3m;
  send_timeout     3m;
  connection_pool_size  256;
  client_header_buffer_size 4k;
  large_client_header_buffers 4 64k;
  request_pool_size  4k;
  output_buffers   4 32k;
  postpone_output  1460;

  # Cache most accessed static files
  open_file_cache          max=10000 inactive=10m;
  open_file_cache_valid    2m;
  open_file_cache_min_uses 1;
  open_file_cache_errors   on;

  # Include each virtual host
  include "/etc/nginx/conf.d/*.conf";
  }

配置虚拟主机

在server2和server3上

  nano -w /etc/nginx/conf.d/mysite.com.conf
  server {
  access_log off;
  error_log /var/log/yoursite.com-error.log;
        listen 80;
        server_name  yoursite.com www.yoursite.com;
        location ~* .(gif|jpg|jpeg|png|ico|wmv|3gp|avi|mpg|mpeg|mp4|flv|mp3|mid|js|css|wml|swf)$ {
        root   /var/www/yoursite.com;
                expires max;
                add_header Pragma public;
                add_header Cache-Control "public, must-revalidate, proxy-revalidate";

        }
        location / {
            root   /var/www/yoursite.com;
            index  index.php index.html index.htm;
        }
      }

三、配置负载均衡

master 只做负载均衡调度，不受理业务请求。在server1上
nano -w /etc/nginx/conf.d/balancer.com.conf upstream balancer { server 192.168.1.109:80 ; server 192.168.1.106:80 ; } server { listen 192.168.1.100:80; server_name yoursite.com; error_log /var/log/yoursite.com-error.log; location / { proxy_set_header Host $host; # 设置Header中的Host proxy_pass http://balancer; } }

master主机只转发请求，所有的请求都转向到slave上进行处理。
2. master 即做负载均衡调度，又做业务请求。

  server {
  access_log off;
  error_log /var/log/yoursite.com-error.log;
          listen 127.0.01:80;
          server_name  yoursite.com www.yoursite.com;

      location / {
              root   /var/www/yoursite.com;
              index  index.php index.html index.htm;
          }

  }

  upstream balancer {
      server 192.168.1.109:80 ;
      server 192.168.1.106:80 ;
      server 127.0.0.1:80 ;
  }

  server {
      listen 192.168.1.100:80;
      server_name yoursite.com;
      error_log /var/log/yoursite.com-error.log;
      location / {
          proxy_set_header Host  $host; # 设置Header中的Host
          proxy_pass http://balancer;
      }

  }

由于负载均衡通过中间节点进行了转发，因此业务端最终接受到的参数与实际参数可能存在差异，如客户端IP地址、Host。
同时，也可以通过转发节点进行header重写：
location / {
    proxy_set_header Host  $host; # 设置Header中的Host
    proxy_pass http://balancer;
}
以上通过重写Host,那么业务受理机，可以接受来处多个负载均衡转发节点转发过来的请求。
location / {
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_pass http://balancer;
}
客户端的IP地址如果不进行Header重写，会在转发节点丢失。

四、负载均衡调度策略

负载均衡的策略控制主要在以下代码中控制

upstream balancer {
    server 192.168.1.109:80 ;
    server 192.168.1.106:80 ;
    server 127.0.0.1:80 ;
}

Nginx支持6种策略:

类型	描述
轮询	默认方式
weight	指定权限
ip_hash	通过IP地址分配
least_conn	最小连接数方式
fair	响应时间方式
url_hash	根据URL地址分配

设置weight的值，指定权重 upstream balancer { server 192.168.1.109:80 weight=10; server 192.168.1.106:80 weight=8; server 127.0.0.1:80 weight=5; }
ip_hash 通过IP地址分配 upstream balancer { ip_hash; server 192.168.1.109:80 ; server 192.168.1.106:80 ; server 127.0.0.1:80 ; }
least_conn 通过最小连接数分配 upstream balancer { least_conn; server 192.168.1.109:80 ; server 192.168.1.106:80 ; server 127.0.0.1:80 ; }
fair 通过服务器的响应时间来分配 upstream balancer { fair; server 192.168.1.109:80 ; server 192.168.1.106:80 ; server 127.0.0.1:80 ; }
url_hash 通过URL地址来分配 upstream balancer { hash $request_uri; server 192.168.1.109:80 ; server 192.168.1.106:80 ; server 127.0.0.1:80 ; }

五、实现SSL

现在越来越多的网站接入SSL，SSK能提高数据传输的安全，当然这也不是绝对的。本节当实现负载均衡下接入SSL的方式。

负载均衡模式下，数据先到master，再由master到slave,如果业务处理服务器仅在自己的专有网络上访问，不直接暴露在外网，SSL可只做到master，如下:

upstream balancer {
    server 192.168.1.109:80 ;
    server 192.168.1.106:80 ;
    server 127.0.0.1:80 ;
}

server {
    listen 192.168.1.100:443;
    server_name yoursite.com;
    error_log /var/log/yoursite.com-error.log;
    ssl on;

    ssl_certificate /usr/local/nginx/cert/server_cert.pem;
    ssl_certificate_key /usr/local/nginx/cert/private.key;
    ssl_session_timeout 5m;
    ssl_ciphers ECDHE-RSA-AES128-GCM-SHA256:ECDHE:ECDH:AES:HIGH:!NULL:!aNULL:!MD5:!ADH:!RC4;
    ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
    ssl_prefer_server_ciphers on;

    location / {
        proxy_pass http://balancer;
    }
}

如果安全性要求较高，或者业务受理服务器可能会直接暴露在外网，那么，可以选择为每一层转发做SSL。

upstream balancer {
    server 192.168.1.109:443 ;
    server 192.168.1.106:443 ;
}

server {
    listen 192.168.1.100:443;
    server_name yoursite.com;
    error_log /var/log/yoursite.com-error.log;
    ssl on;

    ssl_certificate /usr/local/nginx/cert/server_cert.pem;
    ssl_certificate_key /usr/local/nginx/cert/private.key;
    ssl_session_timeout 5m;
    ssl_ciphers ECDHE-RSA-AES128-GCM-SHA256:ECDHE:ECDH:AES:HIGH:!NULL:!aNULL:!MD5:!ADH:!RC4;
    ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
    ssl_prefer_server_ciphers on;

    location / {
        proxy_pass http://balancer;
    }
}

参考文档：
http://nginx.org/en/docs/http/load_balancing.html
http://wiki.nginx.org/HttpUpstreamModule
http://wiki.nginx.org/LoadBalanceExample