keepalived 使用

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keepalived 一般用于实现双机热备，两台服务器提供服务，当其中一台挂掉后，平滑切换到另一个服务上。对外提供一个虚拟IP。

 

环境准备：

主机： 192.168.5.154  ---  nginx负载均衡  ---  tomcat 集群

备机： 192.168.5.158  ---  nginx负载均衡  ---  tomcat 集群

vip：   192.168.5.99

 

一. 安装

wget http://www.keepalived.org/software/keepalived-1.2.17.tar.gz

tar -xvf keepalived-1.2.17.tar.gz

 

cd keepalived-1.2.17

./configure --prefix=/usr/local/keepalived     

make && make install

32位的linux上编译出错：configure: error: No SO_MARK declaration in headers，添加 --disable-fwmark 选项解决

 

二. 配置

./usr/local/keepalived/sbin/keepalived 传统方式启动后，会生成三个keepalived进程，关闭时太复杂了。为便于使用，将其做成服务。

 

cp /usr/local/keepalived/sbin/keepalived /usr/sbin
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived  /etc/init.d/

 

修改系统配置：

vi /etc/sysconfig/keepalived

KEEPALIVED_OPTIONS = "-D -d -S 0 -f /usr/local/keepalived/etc/keepalived/keepalived.conf"         #指定配置文件路径，-d -S 选项打开调试日志

 

主机：keepalived.conf

 
global_defs {
notification_email {
       root@localhost
   }
 
   notification_email_from root@localhost	#不需要邮件通知，直接默认本机接收
   smtp_server localhost
   smtp_connect_timeout 30
   router_id LVS_DEVEL	 #默认即可
}
 
vrrp_script check_run {  #check_run 后面要跟一个空格+{
     script "/usr/local/nginx/check_run.sh"		#指定检测脚本路径
     interval 2
     weight 2
}
 
vrrp_instance VI_1 {
    state MASTER                 #主机
    interface eth0         #监听网卡eth0
    virtual_router_id 52         #路由id，必须与备机一致。运行可能会报错( receive an invalid ip number count 
associated with VRID! )，更换成其它值即可
    priority 100         #优先级，比备机高
    advert_int 1
    authentication {
        auth_type PASS		   #启用密码
        auth_pass 1111         #密码必须与备机一致
    }
 
    track_script {
        check_run         #指定监控脚本。注：配置出错时，keepalived不会退出，只会卡住，一定要检查配置
    }
 
    virtual_ipaddress {
        192.168.5.99         #对外虚拟IP列表，可配置多个
    }
}

 

 

备机：keepalived.conf

vrrp_instance VI_1 {
    state BACKUP     			 #备机            
    interface eth0         
    virtual_router_id 52         #值与主机一致
    priority 90         #优先级比主机低
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111     		 #与主机密码相同    
    }
 
    track_script {
        check_run        
    }
 
    virtual_ipaddress {
        192.168.5.99         #虚拟IP与主机一致
    }
}

 

 check_run.sh nginx运行检测脚本，运行正常返回0，失败返回1，每轮检测2次。 

#!/bin/sh

CHECK_TIME=2		#检测2次

check(){
	curl -m2 http://localhost > /dev/null 2>&1
	return $?
}


while [ $CHECK_TIME -ne 0 ]
do
	let "CHECK_TIME-=1"
	check
	NGINX_OK=$?
	
	if [ $NGINX_OK -eq 0 ]; then
		exit 0
	fi 
	
	if [ $NGINX_OK -ne 1 ] && [ $CHECK_TIME -eq 0 ]; then
		exit 1
	fi
done

  

三. 运行

启动与关闭：

service keepalived start

service keepalived stop

 

启动keepalived后，运行 ip a ，发现生成了vip ，关闭后vip被删除。

[root@test nginx]# ip a
2: eth0:  mtu 1500 qdisc mq state UP qlen 1000
    link/ether 0c:ca:ba:aa:ce:6a brd ff:ff:ff:ff:ff:ff
    inet 192.168.5.158/24 brd 192.168.5.255 scope global eth0
    inet 192.168.5.99/32 scope global eth0
    inet6 fe80::ec4:aaff:fe43:ee6d/64 scope link 
       valid_lft forever preferred_lft forever

  

测试：

http://192.168.5.99 显示正常页面，killall nginx，查看日志 /var/log/messages 发现主机虚拟IP被移除，备机日志显示切换为主机状态

Jun 29 09:56:09 localhost Keepalived_vrrp[19520]: VRRP_Script(check_run) failed
Jun 29 09:56:09 localhost Keepalived_vrrp[19520]: VRRP_Instance(VI_1) Entering FAULT STATE
Jun 29 09:56:09 localhost Keepalived_vrrp[19520]: VRRP_Instance(VI_1) removing protocol VIPs.
Jun 29 09:56:09 localhost Keepalived_vrrp[19520]: VRRP_Instance(VI_1) Now in FAULT state
Jun 29 09:56:09 localhost avahi-daemon[2842]: Withdrawing address record for 192.168.5.99 on eth0.
Jun 29 09:56:09 localhost Keepalived_healthcheckers[19518]: Netlink reflector reports IP 192.168.5.99 removed

  

Jun 29 09:52:13 gw-1 Keepalived_vrrp[12619]: VRRP_Script(check_run) succeeded
Jun 29 09:56:10 gw-1 Keepalived_vrrp[12619]: VRRP_Instance(VI_1) Transition to MASTER STATE
Jun 29 09:56:10 gw-1 Keepalived_vrrp[12619]: VRRP_Instance(VI_1) Entering MASTER STATE
Jun 29 09:56:10 gw-1 Keepalived_vrrp[12619]: VRRP_Instance(VI_1) setting protocol VIPs.
Jun 29 09:56:10 gw-1 Keepalived_vrrp[12619]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.5.99
Jun 29 09:56:10 gw-1 avahi-daemon[3351]: Registering new address record for 192.168.5.99 on eth0.IPv4.
Jun 29 09:56:10 gw-1 Keepalived_healthcheckers[12618]: Netlink reflector reports IP 192.168.5.99 added
Jun 29 09:56:15 gw-1 Keepalived_vrrp[12619]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.5.99

 

访问 http://192.168.5.99 依旧正常