Nginx +keepalived 实现高可用和负载均衡

zhangjih

一、软件安装
1、  安装nginx  参考nginx 安装
2、  安装keepalived 参考keepalived+lvs 的安装
这里提供两个经过我打包的rpm包
1、  nginx 0.7.64  下载
2、  keepalived 1.1.20  下载

二、拓扑结构

                               
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二、实现负载均衡和高可用的说明
1、当用户访问test.woyo.com 时，通过DNS 轮循机制，用户的请求会分别分发到两个keepalived 为master 的服务器上。 实现负载均衡的功能

2、keepalived  通过发送和接收组播包中的同一个virtual_router_id 的中的成员的存活，来确定对方的不可用，一旦检测到对方的不可用，即会切换他的备份角色为主，

即：当真实机192.168.200.143上的keepalived 检测到 真实机192.168.200.144上的keepalived 不可用时，143上对 192.168.200.144的VIP 156的backup 会变为master

3、keepalived 只能实现针对网络层的一个高可用，即 一台装有keepalived的进程检测不到另一台装有keepalived 的存活是，才会发生切换。

4、针对应用层的一个检测keepalived 需要通过vrrp_scripts 来实现

三、看如配置文件样例
1、关建点
         1.互为主备关系的两台机器的  vrrp_instance VI_1 里面的 virtual_router_id 52必需相同

1、 143上的keepalived.conf

1. # Configuration File for keepalived
   # vrrp master master
   global_defs {
   notification_email {
   root@mkrss.com
   }
   notification_email_from root@mkrss.com
   smtp_server localhost
   smtp_connect_timeout 30
   router_id LVS_DEVEL
   }
   vrrp_script chk_nginx {
   script "/tmp/check.sh"
   interval 2
   weight -2
   }
   vrrp_instance VI_1 {
   state MASTER
   interface eth0
   virtual_router_id 52
   priority 100
   advert_int 1
   authentication {
   auth_type PASS
   auth_pass 1111
   }
   track_script {
   chk_nginx 10
   }
   virtual_ipaddress {
   192.168.200.145
   }
   }
   vrrp_instance VI_2 {
   state BACKUP
   interface eth0
   virtual_router_id 53
   priority 80
   advert_int 1
   authentication {
   auth_type PASS
   auth_pass 1111
   }
   virtual_ipaddress {
   192.168.200.146
   }
   }

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2、 144上的keepalived.conf

1. # Configuration File for keepalived
   # vrrp master master
   global_defs {
   notification_email {
   root@mkrss.com
   }
   notification_email_from root@mkrss.com
   smtp_server localhost
   smtp_connect_timeout 30
   router_id LVS_DEVEL2
   }
   #vrrp_script chk_nginx {
   # script "/tmp/check.sh"
   # interval 2
   # weight 2
   vrrp_instance VI_1 {
   state BACKUP
   interface eth0
   virtual_router_id 52
   priority 80
   advert_int 1
   authentication {
   auth_type PASS
   auth_pass 1111
   }
   # track_script {
   # chk_nginx
   # }
   virtual_ipaddress {
   192.168.200.145
   }
   }
   vrrp_instance VI_2 {
   state MASTER
   interface eth0
   virtual_router_id 53
   priority 180
   advert_int 1
   authentication {
   auth_type PASS
   auth_pass 1111
   }
   virtual_ipaddress {
   192.168.200.146
   }
   }

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三、脚本

1. #!/bin/sh
   A=`ps -C nginx --no-header |wc -l`
   if [ $A -eq 0 ]
   then
   /usr/local/nginx/sbin/nginx
   sleep 1
   if [ `ps -C nginx --no-header |wc -l` -eq 0 ]
   then
   killall keepalived
   fi
   fi

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四、测试方法

1、分别在两台机器上写测试文件两台机器创建测试文件

1. echo " php server a " > /usr/local/nginx/html/index.php
   echo " php server b " > /usr/local/nginx/html/index.php

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2、分两在两台机器上启动nginx 和keepalived

1. Server nginx restart
   Server keepalived restart

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3、 分别在两台机器上tail –f  /var/log/messages

1. Jun 13 17:19:35 rs_200_143 Keepalived_vrrp: VRRP_Instance(VI_1) Entering BACKUP STATE
   Jun 13 17:19:35 rs_200_143 Keepalived_vrrp: VRRP sockpool: [ifindex(2), proto(112), fd(9,10)]
   Jun 13 17:19:36 rs_200_143 Keepalived_vrrp: VRRP_Instance(VI_2) Transition to MASTER STATE
   Jun 13 17:19:37 rs_200_143 Keepalived_vrrp: VRRP_Instance(VI_2) Entering MASTER STATE
   Jun 13 17:20:40 rs_200_142 Keepalived_vrrp: VRRP_Instance(VI_2) Entering BACKUP STATE
   Jun 13 17:20:40 rs_200_142 Keepalived_vrrp: VRRP sockpool: [ifindex(2), proto(112), fd(9,10)]
   Jun 13 17:20:41 rs_200_142 Keepalived_vrrp: VRRP_Instance(VI_1) Transition to MASTER STATE
   Jun 13 17:20:42 rs_200_142 Keepalived_vrrp: VRRP_Instance(VI_1) Entering MASTER STATE
   Jun 13 17:20:42 rs_200_142 Keepalived_vrrp: VRRP_Instance(VI_1) setting protocol VIPs.

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4、在一台机器上跑下面的语句

1. for num in {1..10000} ;do curl http://192.168.200.145; echo ;done
   php server a
   php server a
   php server a

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在143上执行server nginx stop
我们会看到如下

1. curl: (7) couldn't connect to host
   curl: (7) couldn't connect to host
   约9个
   php server b
   php server b
   php server b

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同时在143上也会看到如下日志的滚动

1. un 13 17:19:37 rs_200_143 avahi-daemon[1940]: Registering new address record for 192.168.200.146 on eth0.
   Jun 13 17:19:42 rs_200_143 Keepalived_vrrp: VRRP_Instance(VI_2) Sending gratuitous ARPs on eth0 for 192.168.200.146
   Ju 13 17:28:19 rs_200_143 Keepalived_vrrp: VRRP_Instance(VI_1) Transition to MASTER STATE
   Jun 13 17:28:20 rs_200_143 Keepalived_vrrp: VRRP_Instance(VI_1) Entering MASTER STATE
   Jun 13 17:28:20 rs_200_143 Keepalived_vrrp: VRRP_Instance(VI_1) setting protocol VIPs.
   Jun 13 17:28:20 rs_200_143 Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.200.145
   Jun 13 17:28:20 rs_200_143 avahi-daemon[1940]: Registering new address record for 192.168.200.145 on eth0.
   Jun 13 17:28:25 rs_200_143 Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.200.145
   

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