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简介

Keepalived的作用是检测服务器的状态，通常用来搭建高可用服务，比如Nginx、MySQL等。通常高可用主备集群包含2台服务器，一台主服务器处于某种业务的激活状态（即Active状态），另一台备服务器处于该业务的备用状态（即Standby状态)，主服务器上绑定了一个辅助IP，当主服务器出现问题时，主服务器释放该辅助IP，然后备用服务器绑定该辅助IP继续提供服务。

示例场景

3台云主机，其中2台作为主备，其中一台进行流量测试。弹性网卡辅助IP为172.16.0.100。

操作步骤

1.在主服务器和备服务器上搭建Keepalived，使用 yum 方式安装软件包。

# yum install keepalived -y

2.设置抢占默认，配置脚本来check服务。keeplived check脚本/tmp/check_status.sh如下：

#!/bin/sh
if [ ! -f /tmp/down ]; then
    exit 1
fi
exit 0

如何获取AKSK

生成POST token的文件 post_sign.py

生成DELETE token的文件 delete_sign.py

地址切换脚本changed_ip.sh如下：

#!/bin/bash

STATUS=$1
MASTERENI=$2
BACKUPENI=$3
IP=$4

set_master_eni_ip()
{
    TOKEN=`cat /proc/sys/kernel/random/uuid`
    SIGN=`python /root/post_sign.py $MASTERENI $TOKEN`
    curl -H "Host:bcc.bj.baidubce.com" -H "Content-Type:application/json;charset=UTF-8" 

-H "Authorization:$SIGN"  -X POST --data '{"privateIpAddress":"'$IP'"}' "http://bcc.bj.baidubce.com/v1/

eni/$MASTERENI/privateIp?clientToken=$TOKEN"
}

del_backup_eni_ip()
{
    TOKEN=`cat /proc/sys/kernel/random/uuid`
    SIGN=`python /root/delete_sign.py $BACKUPENI $IP $TOKEN`
    curl -H "Host:bcc.bj.baidubce.com" -H "Content-Type:application/json;charset=UTF-8" -H "

Authorization:$SIGN"  -X DELETE "http://bcc.bj.baidubce.com/v1/eni/$BACKUPENI/privateIp/$IP?clientToken=$TOKEN"
}

case "$1" in
    master)
        del_backup_eni_ip
        set_master_eni_ip
        ;;
    backup)
        ;;
esac

注：changed_ip.sh $role $master_eni $backup_eni $ip

• role: 切换的角色，目前脚本仅实现了 master
• master_eni：需要新增IP的网卡
• backup_eni：需要删除IP的网卡

• ip: 需要变动的IP，一般为内网IP

  3.登录主服务器，执行/etc/keepalived/keepalived.conf，修改相关配置。

  ! Configuration File for keepalived
  
  global_defs {
     notification_email {
       acassen@firewall.loc
       failover@firewall.loc
       sysadmin@firewall.loc
     }
     notification_email_from Alexandre.Cassen@firewall.loc
     smtp_server 192.168.200.1
     smtp_connect_timeout 30
     router_id LVS_DEVEL
     vrrp_skip_check_adv_addr
  #   vrrp_strict
     vrrp_garp_interval 0
     vrrp_gna_interval 0
  }
  
  vrrp_instance VI_1 {
      state MASTER
      interface eth0
      virtual_router_id 51
      priority 100
      advert_int 1
      authentication {
          auth_type PASS
          auth_pass 1111
      }
      virtual_ipaddress {
          172.16.0.100
      }
      unicast_src_ip 172.16.0.202
      unicast_peer {
          172.16.0.203
      }
      notify_master "/usr/bin/echo master >> /tmp/keep_status;date >> /tmp/keep_status;/

  4.登录备服务器，执行/etc/keepalived/keepalived.conf，修改相关配置。

  ! Configuration File for keepalived
  
  global_defs {
     notification_email {
       acassen@firewall.loc
       failover@firewall.loc
       sysadmin@firewall.loc
     }
     notification_email_from Alexandre.Cassen@firewall.loc
     smtp_server 192.168.200.1
     smtp_connect_timeout 30
     router_id LVS_DEVEL
     vrrp_skip_check_adv_addr
  #   vrrp_strict
     vrrp_garp_interval 0
     vrrp_gna_interval 0
  }
  
  vrrp_instance VI_1 {
      state BACKUP
      interface eth0
      virtual_router_id 51
      priority 90
      advert_int 1
      authentication {
          auth_type PASS
          auth_pass 1111
      }
      virtual_ipaddress {
          172.16.0.100
      }
      unicast_src_ip 172.16.0.203
      unicast_peer {
          172.16.0.202
      }
      notify_master "/usr/bin/echo master >> /tmp/keep_status;date >> 

• /tmp/keep_status;/root/changed_ip.sh master eni-1jvkdmai1iu1 eni-jdbx8ddgpsz1  172.16.0.100;date >> /tmp/keep_status;"
      notify_backup "/usr/bin/echo backup >> /tmp/keep_status"
      notify_fault "/usr/bin/echo fault >> /tmp/keep_status"
  }

• root/changed_ip.sh master eni-jdbx8ddgpsz1 eni-1jvkdmai1iu1 172.16.0.100;date >> /tmp/keep_status;"
      notify_backup "/usr/bin/echo backup >> /tmp/keep_status"
      notify_fault "/usr/bin/echo fault >> /tmp/keep_status"
  }

说明

• keepalived 启动时可能会设置防火墙，因此测试流量连通性时删除即可。

iptables -D INPUT 1

5.功能验证，在云服务器1生成down文件

touch /tmp/down

删除此文件，会自动切回主，断网时间5秒左右。