Keepalived使用

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 {
     [e-mail]
   }
   notification_email_from [e-mail]
   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 {
     [e-mail]
   }
   notification_email_from [e-mail]
   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：

1.     eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
2.     link/ether 00:0c:29:aa:a1:e4 brd ff:ff:ff:ff:ff:ff
3.     inet 172.16.2.123/22 brd 172.16.3.255scope global eth0
4.     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：

1. 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
2.     link/ether 00:0c:29:2b:94:3b brd ff:ff:ff:ff:ff:ff
3.     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：

1.    eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
2.     link/ether 00:0c:29:aa:a1:e4 brd ff:ff:ff:ff:ff:ff
3.     inet 172.16.2.123/22 brd 172.16.3.255scope global eth0

从服务器的情况：

1. 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
2.     link/ether 00:0c:29:2b:94:3b brd ff:ff:ff:ff:ff:ff
3.     inet 172.16.2.130/22 brd 172.16.3.255 scope global eth0
4.     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。