Keepalived

原创已于 2022-11-02 12:32:40 修改 · 110 阅读

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于 2020-12-14 17:13:30 首次发布

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本文详细介绍了Keepalived的安装配置过程，以及如何通过VRRP_script进行健康检查。在服务器A和B上分别配置了用于监控PostgreSQL和OpenFlow的服务，确保在主服务器故障时能平滑切换到备用服务器。配置中涉及到了vrrp_instance的状态、优先级、认证和虚拟IP地址等关键参数，以及check_script的使用，如check_pg_alived和chk_openflow_process。当检测脚本返回值非0时，将降低优先级，触发主从切换。

Keepalived

- - 服务器A
  - 服务器B

keepalived实现服务高可用全面

keepalived之vrrp_script详解

Keepalived状态切换的条件和因素

keepalived安装配置
systemctl start keepalived
keepalived正常运行后，会启动3个进程，其中一个是父进程，负责监控其子进程。一个是vrrp子进程，另外一个是checkers子进程。

[root@ ~]# ps -ef | grep keep
root      47386  47323  0 10:47 pts/0    00:00:00 grep --color=auto keep
root     197314      1  0  2018 ?        00:02:52 /usr/sbin/keepalived -D -d -S 0
root     197315 197314  0  2018 ?        00:50:52 /usr/sbin/keepalived -D -d -S 0
root     197316 197314  0  2018 ?        00:18:22 /usr/sbin/keepalived -D -d -S 0

安装
yum install keepalived -y
或者tar.gz安装

启动
service keepalived start

停止
service keepalived stop

重启
service keepalived restart

https://www.cnblogs.com/darendu/archive/2019/05/17/10881791.html

keepalived实现服务高可用

Keepalived原理与实战精讲–VRRP协议

keepalived双进程双VIP配置及原理图

/opt/context/keepalive_check/checkNginx.sh   注意脚本名字不要跟 nginx 进程名字重了 check_nginx也不行
auth_pass 5678   两进程密码要不一样
要配置抢占 不写nopreempt   配置不抢占写nopreempt的问题 https://www.cnblogs.com/arjenlee/p/9258188.html#auto_id_2

服务器A

! Configuration File for keepalived

#global_defs {
#   notification_email {
#     francs3@163.com
#   }
#   smtp_server 127.0.0.1
#   smtp_connect_timeout 30
#   router_id DB1_PG_HA_MASTER
#}

vrrp_script check_pg_alived {
    script "/usr/local/bin/pg_monitor.sh"
    #script "/home/postgres/bin/psql -c 'select 1;'"
    interval 2
    fall 3    # require 3 failures for KO
}

vrrp_instance VI_POSTGRES {
    state MASTER
    interface bond0.170     #网卡名对应修改
    virtual_router_id 126
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    track_script {
        check_pg_alived
    }
    virtual_ipaddress {
        11.115.127.170     #keepalive对外提供虚ip
    }
    smtp_alert
    notify_master /usr/local/bin/active_standby.sh
}

vrrp_instance VI_OPENFLOW {
    state BACKUP
    interface bond0.170
    virtual_router_id 151
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1133
    }
    virtual_ipaddress {
        11.115.127.169
    }

    track_script {
       # chk_openflow_process
    }
}

服务器B

! Configuration File for keepalived

#global_defs {
#   notification_email {
#     francs3@163.com
#   }
#   smtp_server 127.0.0.1
#   smtp_connect_timeout 30
#   router_id DB1_PG_HA_SLAVE
#}

# vrrp_script check_pg_alived {
#    script "/usr/local/bin/pg_monitor.sh"
#    #script "/home/postgres/bin/psql -c 'select 1;'"
#    interval 10
#    fall 3    # require 3 failures for KO
#}

vrrp_script chk_openflow_process {
    script "/etc/keepalived/check_of.sh"
    interval 2           
    weight -20 
}

vrrp_instance VI_POSTGRES {
    state BACKUP
    interface bond0.170     #网卡名对应修改
    virtual_router_id 126
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    track_script {
       #check_pg_alived
    }
    virtual_ipaddress {
        11.115.127.170     #keepalive对外提供虚ip
    }
    #smtp_alert
    #notify_master /usr/local/bin/active_standby.sh
}

vrrp_instance VI_OPENFLOW {
    state MASTER
    interface bond0.170
    virtual_router_id 151
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1133
    }
    virtual_ipaddress {
        11.115.127.169
    }

    track_script {
        chk_openflow_process
    }
}

vrrp_script 里的script返回值为0时认为检测成功，其它值都会当成检测失败；

weight 为负时，脚本检测成功时此weight不影响priority，检测失败时priority – abs(weight)

	主失败:
		主 priority – abs(weight) < 从priority 时会切换主从
	主成功:
		主 priority > 从priority 主依然为主


检测nginx进程存在，count >0  exit 0 脚本检测成功时此weight不影响priority
检测nginx进程不存在，count =0  exit 1 脚本检测失败 priority-20
nginx起来之后，检测nginx进程存在，count >0  exit 0 脚本检测成功时此weight不影响priority，还是原来配置的100

vim /etc/keepalived/check_of.sh

#!/bin/bash

count=`ps aux | grep -v grep | grep nginx | wc -l` 
   
if [ $count -gt 0 ]; then    # -gt 大于
	exit 0
else
	exit 1
fi