nginx+keepalived实现双机热备的高可用
这篇文章简单介绍利用keepalived软件，实现对nginx服务器的高可用，即实现故障自动切换。假设你已经安装好nginx，下面介绍keepalived的安装和使用。keepalived安装
[*]yum install openssl-devel
[*]cd /tmp
[*]wget http://www.keepalived.org/software/keepalived-1.2.2.tar.gz
[*]tar xzf keepalived-1.2.2.tar.gz
[*]cd keepalived-1.2.2
[*]./configure
[*]make && make install
[*]cp /usr/local/etc/rc.d/init.d/keepalived /etc/init.d/
[*]cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/
[*]chmod +x /etc/init.d/keepalived
[*]chkconfig --add keepalived
[*]chkconfig keepalived on
[*]mkdir /etc/keepalived
[*]ln -s /usr/local/sbin/keepalived /usr/sbin/
keepalived的配置更详细的keepalived配置文件说明可以执行man keepalived.conf查看。
我们假设主服务器IP:192.168.1.103,从服务器ip:192.168.1.101 虚拟ip:192.168.1.110
下面对主服务器的keepalived进行配置：
[*]vi /etc/keepalived/keepalived.conf
[*]global_defs {
[*] notification_email {
[*] admin@centos.bz
[*] }
[*] notification_email_from keepalived@domain.com
[*] smtp_server 127.0.0.1
[*] smtp_connect_timeout 30
[*] router_id LVS_DEVEL
[*]}
[*]vrrp_script chk_http_port {
[*] script "/opt/nginx_pid.sh"
[*] interval 2
[*] weight 2
[*]}
[*]vrrp_instance VI_1 {
[*] state MASTER ############ 辅机为 BACKUP
[*] interface eth0
[*] virtual_router_id 51
[*] mcast_src_ip 192.168.1.103
[*] priority 102 ########### 权值要比 back 高
[*] advert_int 1
[*] authentication {
[*] auth_type PASS
[*] auth_pass 1111
[*] }
[*]track_script {
[*] chk_http_port ### 执行监控的服务
[*] }
[*] virtual_ipaddress {
[*] 192.168.1.110
[*] }
[*]}
从服务器：
[*]global_defs {
[*] notification_email {
[*] admin@centos.bz
[*] }
[*] notification_email_from keepalived@domain.com
[*] smtp_server 127.0.0.1
[*] smtp_connect_timeout 30
[*] router_id LVS_DEVEL
[*]}
[*]vrrp_script chk_http_port {
[*] script "/opt/nginx_pid.sh"
[*] interval 2
[*] weight 2
[*]}
[*]vrrp_instance VI_1 {
[*] state BACKUP
[*] interface eth0
[*] virtual_router_id 51
[*] mcast_src_ip 192.168.1.101
[*] priority 101 ##########权值 要比 master 低。。
[*] advert_int 1
[*] authentication {
[*] auth_type PASS
[*] auth_pass 1111
[*] }
[*]track_script {
[*] chk_http_port ### 执行监控的服务
[*] }
[*] virtual_ipaddress {
[*] 192.168.1.110
[*] }
[*]}
之后分别在主从服务器建立nginx的监控脚本：
[*]vi /opt/nginx_pid.sh
[*]#!/bin/bash
[*]A=`ps -C nginx --no-header |wc -l`
[*]if [ $A -eq 0 ];then
[*] /usr/local/nginx/sbin/nginx
[*] sleep 3
[*] if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
[*] killall keepalived
[*] fi
[*]fi
然后分别启动主从服务器的keepalived:
[*]service keepalived start
keepalived的测试我们在主服务器上执行命令ip a，显示如下：
[*]2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
[*] link/ether 00:0c:29:aa:a1:e4 brd ff:ff:ff:ff:ff:ff
[*] inet 192.168.1.103/24 brd 255.255.255.255 scope global eth0
[*] inet 192.168.1.110/32 scope global eth0
证明主服务器已经绑定了虚拟ip 192.168.1.110
在从服务器上执行命令ip a,显示如下：
[*]2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
[*] link/ether 00:0c:29:2b:94:3b brd ff:ff:ff:ff:ff:ff
[*] inet 192.168.1.101/24 brd 255.255.255.255 scope global eth0
显示表明从服务器上没有绑定vip 192.168.1.110,只有本机真实ip192.168.1.101
下面我们停止主服务器的nginx进程，再看看ip绑定情况:
主服务器的情况：
[*]2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
[*] link/ether 00:0c:29:aa:a1:e4 brd ff:ff:ff:ff:ff:ff
[*] inet 192.168.1.103/24 brd 255.255.255.255 scope global eth0
从服务器的情况：
[*]2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
[*] link/ether 00:0c:29:2b:94:3b brd ff:ff:ff:ff:ff:ff
[*] inet 192.168.1.101/24 brd 255.255.255.255 scope global eth0
[*] inet 192.168.1.110/32 scope global eth0
由此可见vip已经指向了从服务器。
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