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keepalived的简单使用

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keepalived的简单使用

原理简述

keepalived配合nginx实现nginx的高可用, 也就是需要keepalived检测到nginx宕机时停用keepalived, 备用keepalived会自动接收过来。

keepalived功能有很多, 此篇只是最简单的配合ngxin实现高可用的demo。

安装

    yum install -y curl gcc openssl-devel libnl3-devel net-snmp-devel

  • yum install -y keepalived

  • systemctl start keepalived

  • systemctl restart keepalived

  • systemctl stop keepalived

  • systemctl enable keepalived

  • vim /etc/keepalived/keepalived.conf

    ! Configuration File for keepalived

# 定义虚拟路由, 必须叫VI_1
vrrp_instance VI_1 {
    state MASTER #设置为主服务器, 备份服务器设置为BACKUP
    interface enp0s3 #监控的网络接口(ifconfig或者ip addr指令找出网卡
    priority 100 #(优先级, 主机大一点, 备份机小一点
    virtual_router_id 99 #同一个vrrp_instance下routerId必须是一致的

    authentication {
        auth_type PASS #vrrp认证方式主备必须一致
        auth_pass 12345 #密码
    }

    virtual_ipaddress {
        192.168.0.99 #虚拟ip, 主从一致, 可配置多个
    }
}

  • 另外一台机相同方法, 相同配置(state改成BACKUP, priority调整调一下, 此例中是80

vrrp 的主从并不是通过stat配置的MASTER和BACKUP决定的, 是通过优先级决定的

    默认日志位置: /var/log/message位置修改参考: keepalived 配置日志方法

参考2: Keepalived原理介绍和配置实践

参考4: https://codor.lanzoue.com/b012qnsvc 密码:1i77

检查是否脑裂

    a或者b进行查看, 默认的广播通道为224.0.0.18 (我把时间删除了, 内容是我改的

    192.168.0.111 > 224.0.0.18: VRRPv2, Advertisement, vrid 99, prio 100, authtype simple, intvl 1s, length 20
192.168.0.117 > 224.0.0.18: VRRPv2, Advertisement, vrid 99, prio 80, authtype simple, intvl 1s, length 20
192.168.0.111 > 224.0.0.18: VRRPv2, Advertisement, vrid 99, prio 100, authtype simple, intvl 1s, length 20
192.168.0.117 > 224.0.0.18: VRRPv2, Advertisement, vrid 99, prio 80, authtype simple, intvl 1s, length 20
192.168.0.111 > 224.0.0.18: VRRPv2, Advertisement, vrid 99, prio 100, authtype simple, intvl 1s, length 20
192.168.0.117 > 224.0.0.18: VRRPv2, Advertisement, vrid 99, prio 80, authtype simple, intvl 1s, length 20

  • 如果结果如上, 说明出现了脑裂(主备都向外宣誓我是老大,

    防火墙(推荐:

    firewall-cmd --add-rich-rule='rule protocol value="vrrp" accept' --permanent
firewall-cmd --reload

    iptables:

    iptables -A INPUT -s 192.168.1.0/24 -d 224.0.0.18 -j ACCEPT
iptables -A INPUT -s 192.168.1.0/24 -p vrrp -j ACCEPT

    不存在可以进行安装, yum install iptables-services

    • 参考2: centos7 keepalived VRRP协议 firewalld配置

    • 参考4: 使用keepalived时iptables需要开放的协议

  • 最后附上正常运行结果, 即只有100或者80优先级的机器来广播自己是老大

    09:26:55.782258 IP 192.168.0.111 > 224.0.0.18: VRRPv2, Advertisement, vrid 99, prio 100, authtype simple, intvl 1s, length 20
09:26:56.782910 IP 192.168.0.111 > 224.0.0.18: VRRPv2, Advertisement, vrid 99, prio 100, authtype simple, intvl 1s, length 20
09:26:57.783787 IP 192.168.0.111 > 224.0.0.18: VRRPv2, Advertisement, vrid 99, prio 100, authtype simple, intvl 1s, length 20
09:26:58.784709 IP 192.168.0.111 > 224.0.0.18: VRRPv2, Advertisement, vrid 99, prio 100, authtype simple, intvl 1s, length 20
09:26:59.784792 IP 192.168.0.111 > 224.0.0.18: VRRPv2, Advertisement, vrid 99, prio 100, authtype simple, intvl 1s, length 20
09:27:00.785171 IP 192.168.0.111 > 224.0.0.18: VRRPv2, Advertisement, vrid 99, prio 100, authtype simple, intvl 1s, length 20

测试ip漂移

`ip漂移`: 就是主备切换过程成, vip漂到真实ip上的过程. 也称为`主备切换`.

测试过程就是停用master机器上面的keepalived或者关机master机器, 查看backup机器是否正常接过来, 一般1s左右可以切换过去. 当出现脑裂情况的时候切换过程也能实现, 只是很慢大约7s左右. 具体原因未深究。

至此位置简单使用就完成了, 下面介绍几个功能配置

VRRP脚本

    cd /etc/keepalived/

  • vim nginx_check.sh

    #!/bin/bash
count=`ps -C nginx --no-header |wc -l`
if [ $count -eq 0 ];then
		killall keepalived
fi

  • 赋予执行权限: chmode +x nginx_check.sh

  • vim keepalived.conf

    vrrp_instance同级, 其中

    • chk_nginx: 脚本名称, 自定义的

    • script: 脚本位置

    • interval: 执行间隔

    • weight: 权重, 如果是负数, 当执行失败时候会影响vrrp_instance中的优先级priority, 因为主备切换是通过优先级的高低的进行切换的, 所以也可以通过这个优先级来进行主动控制主备切换. 而脚本中的内容可以很灵活地实现很多功能. 此个demo中只是简单实现检测到ngxin关闭后自动关闭keepalived, 也可以实现检测启动后进行开启, 然后延迟2s后查看是否启动成功, 未成功再进行关闭keepalived或者降低优先级(配合右键通知。

      vrrp_script chk_nginx {
	script "/etc/keepalived/nginx_check.sh"
	interval 2
	#weight -30
}

  • 配置到vrrp_instance中, 与authentication和virtual_ipaddress同级

    track_script {
	chk_nginx
}

  • 修改后的配置文件

    ! Configuration File for keepalived

vrrp_script chk_nginx {
    script "/etc/keepalived/nginx_check.sh"
    interval 2
    #weight -30
}

vrrp_instance VI_1 {
    state MASTER
    interface enp0s3
    priority 100
    advert_int 1
    virtual_router_id 99
    authentication {
        auth_type PASS
        auth_pass 221531
    }

    track_script {
        chk_nginx
    }

    virtual_ipaddress {
        192.168.0.99
    }
}

  • 测试

  • 参考:

    • 参考2: Keepalived 的主备切换怎么做

邮件配置

mail指令。

    mail: yum -y install mailx

  • vim /etc/mail.rc, 在末尾处添加

    set from=xxx@163.com
set smtp=smtp.163.com
set smtp-auth-user=xxx@qq.com
set smtp-auth-password=KJFHTOSXZQPNFAIU  #邮箱需要开启POP3/SMTP服务并设置密钥
set smtp-auth=login
set ssl-verify=ignore

  • 测试mail功能: echo test mail | mail -s testa 收件人id@qq.com

    • -s 后面是主题的意思

    • echo test maill 中的test mail 是邮件正文。

  • 配置到keepalived中, 方法1

      vim mail_send.sh(记得赋予执行权限

      ./mail_send.sh master进行测试

      #!/bin/bash
contact='收件人邮箱@qq.com'
notify( {
  	  mailsubject="$(hostname to be $1, vip  转移"
  	  mailbody="$(date +'%F %T': vrrp transition, $(hostname changed to be $1"
  	  echo "$mailbody" | mail -s "$mailsubject" $contact
}
case $1 in
  	  master
  			  notify master
  			  ;;
  	  backup
  			  notify backup
  			  ;;
  	  fault
  			  notify fault
  			  ;;
  	  *
  			  echo "Usage: $(basename $0 {master|backup|fault}"
  			  exit 1
  			  ;;
esac

    • 修改配置文件: vim keepalived.conf

      notify_master "/etc/keepalived/mail_senc.sh master"
notify_backup "/etc/keepalived/mail_send.sh backup"
notify_fault "/etc/keepalived/mail_send.sh fault"

    • 整体配置文件

      ! Configuration File for keepalived

vrrp_script chk_nginx {
    script "/etc/keepalived/nginx_check.sh"
    interval 2
    #weight -30
}

vrrp_instance VI_1 {
    state MASTER
    interface enp0s3
    priority 100
    advert_int 1
    virtual_router_id 99
    # 当进入master/backup/fault状态时触发脚本, 可携带参数
    notify_master "/etc/keepalived/mail_send.sh master"
    notify_backup "/etc/keepalived/mail_send.sh backup"
    notify_fault "/etc/keepalived/mail_send.sh fault"
    authentication {
        auth_type PASS
        auth_pass 221531
    }

    track_script {
        chk_nginx
    }

    virtual_ipaddress {
        192.168.0.99
    }
}

  • 配置到keepalived中, 方法2

      #!/bin/bash
contacts='收件人邮箱1, 收件人邮箱2'
ip a > ipa_temp.txt

echo "$(date +'%F %T': Keepalived instance I became MASTER on $(hostname.    --- from master" | mail -s "Master Keepalived notification" -a ipa_temp.txt "$contacts"

    • 修改配置文件: vim keepalived.conf

      root是执行人和所在组

      notify_master /etc/keepalived/mail_send_master.sh root root
notify_backup /etc/keepalived/mail_send_back_up.sh root root
notify_fault /etc/keepalived/mail_send_faul.sh troot root

  • 测试状态转移时有没有邮箱接收到即可, 通过重启, 停用

    • 参考1: keepalived 日志设置 、邮箱设置和通知

    • 参考3: Keepalived故障切换时的邮件通知

    • 参考4: mail指令同时发送给多个用户

学习链接

    LVS负载均衡
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编程笔记 » keepalived的简单使用

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