keepalived是什么？
Keepalived软件起初是专为LVS负载均衡软件设计的，用来管理并监控LVS集群系统中各个服务节点的状态，后来又加入了可以实现高可用的VRRP功能。因此，Keepalived除了能够管理LVS软件外，还可以作为其他服务（例如：Nginx、Haproxy、MySQL等）的高可用解决方案软件。
Keepalived软件主要是通过VRRP协议实现高可用功能的。VRRP是Virtual Router RedundancyProtocol(虚拟路由器冗余协议）的缩写，VRRP出现的目的就是为了解决静态路由单点故障问题的，它能够保证当个别节点宕机时，整个网络可以不间断地运行。
所以，Keepalived 一方面具有配置管理LVS的功能，同时还具有对LVS下面节点进行健康检查的功能，另一方面也可实现系统网络服务的高可用功能。
keepalived官网http://www.keepalived.org
1.1 keepalived的相关的文件
keepalived的执行命令：/data/apps/keepalived/sbin/keepalived
keepalived的配置文件：/data/apps/keepalived/etc/keepalived/keepalived.conf
keepalived的Pid文件：/data/apps/keepalived/run/keepalived.pid
1.2 keepalived的启停止方式
注意：不要去修改/data/apps/keepalived/etc/sysconfig/keepalived文件
启动方式：keepalived -f 配置文件(绝对路径) -p PID文件(绝对路径)
关闭方式：kill $( cat PID文件(绝对路径) )
1.3 脚本内容
注意：该脚本只能Linux的超级用户root才能启动,因为脚本中有进行限制
#!/bin/bash
## Define variables
RETVAL=0
Conf="/data/apps/keepalived/etc/keepalived/keepalived.conf"
Exce="/data/apps/keepalived/sbin/keepalived"
Pid="/data/apps/keepalived/run/keepalived.pid"
# Determine the user to execute
if [ "$UID" -ne "$RETVAL" ];then
echo "Must be root to run scripts"
exit 1
fi
# Load local functions library
[ -f /etc/init.d/functions ] && source /etc/init.d/functions
# Define functions
start(){
if [ ! -f "$Pid" ];then
$Exce -f $Conf -p $Pid >/dev/null 2>&1
RETVAL=$?
if [ $RETVAL -eq 0 ];then
action "Start keepalived service" /bin/true
else
action "Start keepalived service" /bin/false
fi
else
echo "keepalived service is running"
fi
return $RETVAL
}
stop(){
if [ -f "$Pid" ];then
kill $(cat $Pid) >/dev/null 2>&1
RETVAL=$?
if [ $RETVAL -eq 0 ];then
action "Stop keepalived service" /bin/true
else
action "Stop keepalived service" /bin/false
fi
else
echo "keepalived service is not running"
fi
return $RETVAL
}
status(){
if [ -f "$Pid" ];then
echo "keepalived service is running"
else
echo "keepalived service is not running"
fi
return $RETVAL
}
# case local functions
case "$1" in
start)
start
RETVAL=$?
;;
stop)
stop
RETVAL=$?
;;
status)
status
RETVAL=$?
;;
restart)
stop
sleep 2
start
RETVAL=$?
;;
*)
echo "USAGE:$0{status|start|stop|restart}"
exit 1
esac
# Scripts return values
exit $RETVAL
