计划任务WebCron之CronJob搭建(3)

Cron的特殊性，在双机热备集群中，只有一台是提供服务的。当CronJobA故障时，停掉cron服务，CronJobB启动cron并接替CronJobA继续服务。CronJobA在恢复后，Keepalived不应该切回去。

所以我们要在配置文件加入 nopreempt 非抢占，但是这个参数只能用于state 为backup，故我们在用Keepalived的时候最好master 和backup的state都设置成backup 让其通过priority来竞争。

节点高可用解决

keepalived在线安装：

yum -y install keepalived ipvsadm

在Master(CronJobA)配置：

vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
router_id cronha
}
vrrp_instance VI_1 {
    state BACKUP
    interface eth1
    virtual_router_id 51
    priority 101
    advert_int 1
    #防止抢占资源
    nopreempt
    authentication {
        auth_type PASS
        auth_pass 1111
    }
   #指定当切换到master时，执行的脚本
   notify_master /etc/keepalived/scripts/cronstart
   #指定当切换到backup时，执行的脚本
   notify_backup /etc/keepalived/scripts/cronstop
   virtual_ipaddress {
        172.88.0.254
    }
}

在Backup(CronJobB)配置：

vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
router_id cronha
}

vrrp_instance VI_1 {
    state BACKUP
    interface eth1
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
   notify_master /etc/keepalived/scripts/cronstart
   notify_backup /etc/keepalived/scripts/cronstop 
   virtual_ipaddress {
        172.88.0.254
    }
}

• 做为Master和Backup时需要的脚本

#创建目录
mkdir /etc/keepalived/scripts

#启动cron脚本
vim /etc/keepalived/scripts/cronstart
#!/bin/bash
/etc/init.d/crond start
#微信告知切换
/etc/keepalived/scripts/weixin

#添加执行权限
chmod +x /etc/keepalived/scripts/cronstart

#关闭cron脚本
vim /etc/keepalived/scripts/cronstop
#!/bin/bash
/etc/init.d/crond stop

#添加执行权限
chmod +x /etc/keepalived/scripts/cronstop

在两台CronJob上配置

• 关闭cron自启动服务

chkconfig crond off

• 启动Keepalived并加入开机启动：

/etc/init.d/keepalived restart
chkconfig keepalived on