Keepalived使用

ezeke

　　Keepalived使用
　　利用keepalived软件，实现对nginx负载均衡服务器的高可用，即实现故障自动切换。下面介绍keepalived的安装和使用。

LB_1 : 172.16.2.130 (Nginx负载均衡服务器群1)
LB_2 : 172.16.2.123 (Nginx负载均衡服务器群2)
VIP : 172.16.2.122 (虚拟IP)

keepalived安装

yum install openssl-devel
cd /usr/local/soft
wget http://www.keepalived.org/software/keepalived-1.2.8.tar.gz
tar xzf keepalived-1.2.8.tar.gz
cd keepalived-1.2.8
./configure --prefix=/usr/local/app/keepalived --sysconf=/etc
make && make install
chmod a+x /etc/init.d/keepalived
chkconfig --add keepalived
chkconfig keepalived on
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:172.16.2.130,从服务器ip:172.16.2.123 虚拟ip:172.16.2.122
下面对主服务器的keepalived进行配置：
 
 

! Configuration File for keepalived
global_defs {
notification_email {
275553385@qq.com
}
notification_email_from keepalived@domain.com
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id node1
}
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 172.16.2.123
priority 240                  ########### 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 {
172.16.2.122
}
}
从服务器：
 
 

! Configuration File for keepalived
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 172.16.2.130
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 {
172.16.2.122
}
}
之后分别在主从负载均衡服务器建立nginx的监控脚本：
vim /opt/nginx_pid.sh
 

#!/bin/bash
A=`ps -C nginx --no-header |wc -l`               
if [ $A -eq 0 ];then                                       
/usr/local/app/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
　　测试:
 

keepalived的测试

我们在主服务器上执行命令ip a，显示如下：

•     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 172.16.2.123/22 brd 172.16.3.255scope global eth0
  
•     inet 172.16.2.122/32 scope global eth0
  

证明主服务器已经绑定了虚拟ip 172.16.2.122
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 172.16.2.130/22 brd 172.16.3.255 scope global eth0
  

显示表明从服务器上没有绑定vip 172.16.2.122,只有本机真实ip172.16.2.130
下面我们停止主服务器的keepalived进程，再看看ip绑定情况:
主服务器的情况：

•    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 172.16.2.123/22 brd 172.16.3.255scope 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 172.16.2.130/22 brd 172.16.3.255 scope global eth0
  
•     inet 172.16.2.122/32 scope global eth0
  

由此可见vip 172.16.2.122已经指向了从服务器。