一、背景

项目内部工程7层调用，走nginx，将域名使用dnsPod 轮询解析在 两个vip上了。

dnsPod 能实现将域名轮询解析在多个ip上，实现负载， 但是无法对被轮询的ip所在的主机上的监听的端口（此处为80）做健康检查，所以需要keepalived绑定vip结合检测脚本，实现高可用。

nginx01 + nginx02 + keepalived ----> vip01
nginx03 + nginx04 + keepalived ----> vip02

将域名 www.example.com 解析在 vip01 vip02 上，既实现了负载均衡，又实现了高可用。

这种主备模式，每组一台备机，有点浪费资源，怎么才能充分利用起来呢？

我们可以将 keepalived改造为vrrp双实例，每组绑定2个vip，这样正常情况下每台主机能分到一个vip，就算有某台主机故障了，该组另一台最多多承接1/4 的流量，结合监控功告警，可以快速恢复。

nginx01 + nginx02 + keepalived ---> vip01 vip03
nginx03 + nginx04 + keepalived ---> vip02 vip04

二、keepalived配置

以 nginx01 + nginx02 + keepalived -------> vip01 vip03 为例

BACKUP <-----> MASTER（vip01）
MASTER（vip03）<-----> BACKUP

nginx01： 192.168.1.101
nginx02：192.168.1.102
vip01：192.168.1.110
vip03：192.168.1.120

对nginx01

cat /etc/keepalived/keepalived.conf

! Configuration File for keepalived
global_defs {
   router_id ka
}

#Insertcheckscript
#InsertvrrpInstance

vrrp_script chk_innernginx01 {
   script "/etc/keepalived/check_innernginx.sh"
   interval 2
   timeout 2
   rise 3
   fall 3
}

vrrp_instance innernginx01 {
   state BACKUP
   interface eth0
   virtual_router_id 77
   priority 90
   advert_int 1
#   nopreempt

   authentication {
        auth_type PASS
        auth_pass 111111
    }

    unicast_src_ip  192.168.1.101
    unicast_peer {
                    192.168.1.102
     }


    virtual_ipaddress {
       192.168.1.110/24
    }

    track_script {
        chk_innernginx01
    }
}

###############################################

vrrp_script chk_innernginx02 {
   script "/etc/keepalived/check_innernginx.sh"
   interval 2
   timeout 2
   rise 3
   fall 3
}

vrrp_instance innernginx02 {
   state MASTER
   interface eth0
   virtual_router_id 99
   priority 100
   advert_int 1
#   nopreempt

   authentication {
        auth_type PASS
        auth_pass 111111
    }

    unicast_src_ip  192.168.1.101
    unicast_peer {
                    192.168.1.102
     }


    virtual_ipaddress {
       192.168.1.120/24
    }

    track_script {
        chk_innernginx02
    }
}

对nginx02

cat /etc/keepalived/keepalived.conf

! Configuration File for keepalived
global_defs {
   router_id ka
}

#Insertcheckscript
#InsertvrrpInstance

vrrp_script chk_innernginx01 {
   script "/etc/keepalived/check_innernginx.sh"
   interval 2
   timeout 2
   rise 3
   fall 3
}

vrrp_instance innernginx01 {
    state MASTER
    interface eth0
    virtual_router_id 77
    priority 100
    advert_int 1
#    nopreempt

    authentication {
        auth_type PASS
        auth_pass 111111
    }

    unicast_src_ip  192.168.1.102
    unicast_peer {
                    192.168.1.101
     }

    virtual_ipaddress {
       192.168.1.110/24
    }

    track_script {
        chk_innernginx01
    }
}

#################################################
vrrp_script chk_innernginx02 {
   script "/etc/keepalived/check_innernginx.sh"
   interval 2
   timeout 2
   rise 3
   fall 3
}

vrrp_instance innernginx02 {
    state BACKUP
    interface eth0
    virtual_router_id 99
    priority 90
    advert_int 1
#    nopreempt

    authentication {
        auth_type PASS
        auth_pass 111111
    }

    unicast_src_ip  192.168.1.102
    unicast_peer {
                    192.168.1.101
     }

    virtual_ipaddress {
       192.168.1.120/24
    }

    track_script {
        chk_innernginx02
    }
}

检测脚本

cat /etc/keepalived/check_innernginx.sh

#!/bin/bash

if ! ps aux | grep -w "nginx" | grep -v "grep" | grep -w "master process" > /dev/null 2>&1; then
  /usr/local/openresty/nginx/sbin/nginx
  if ! ps aux | grep -w "nginx" | grep -v "grep" | grep -w "master process" > /dev/null 2>&1; then
    exit 1
  fi
fi

测试

# systemctl  restart keepalived
# ip addr list

三、参考

keepalived双主多实例
https://blog.csdn.net/zfx1997/article/details/78765540

如何运用VRRP协议实现双主双备网络？
https://blog.csdn.net/m0_47452405/article/details/107039453

LVS+keepalived实现双实例
https://blog.csdn.net/cx55887/article/details/82830816

keepalived双实例配置
https://blog.51cto.com/jiayimeng/1896830

安装keepalived高可用（双实例）
https://www.cnblogs.com/mashuang/p/10074675.html

keepalived配置多实例高可用
https://cloud.tencent.com/developer/article/1843033