原文：http://www.hiceon.com/index.php/category/operation/
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 /usr/local/src wget http://www.keepalived.org/software/keepalived-1.2.2.tar.gz tar xvzf 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
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
}
}从服务器配置：
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=<code>ps -C nginx --no-header |wc -l
if [ $A -eq 0 ];then
/usr/local/nginx/sbin/nginx
sleep 3
if [ <code>ps -C nginx --no-header |wc -l</code> -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: 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: 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: 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：
由此可见vip已经指向了从服务器。 参考：http://www.keepalived.org/pdf/UserGuide.pdf 2: eth0: 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
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