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高可用集群KEEPALIVED

news 2025/11/27 1:25:45

一.高可用集群

1.1 集群类型

  • LB: 负载均衡
  • HA: 高可用集群
  • SPoF: 解决单点故障
  • HPC: 高性能集群

1.2 系统可用性

A=MTBF/(MTBF+MTTR)

99.95%:(60*24*30)*(1-0.9995)=21.6分钟 #一般按一个月停机时间统计

1.3 实现高可用

提升系统高可用的解决方案：降低平均故障时间

解决方案：建立冗余机制

  • active/passive 主/备
  • active/active 双主
  • active --> HEARTBEAT --> passive
  • active HEARTBEAT active

二.Keepalived 部署

2.1 keepalived 简介

vrrp 协议的软件实现，原生设计目的为了高可用 ipvs服务

功能：

  • 基于vrrp协议完成地址流动
  • 为vip地址所在的节点生成ipvs规则(在配置文件中预先定义)
  • 为ipvs集群的各RS做健康状态检测
  • 基于脚本调用接口完成脚本中定义的功能，进而影响集群事务，以此支持nginx、haproxy等服务

2.2 Keepalived 架构

  • 用户空间核心组件：

        vrrp stack：VIP消息通告

        checkers：监测real server

        system call：实现 vrrp 协议状态转换时调用脚本的功能

        SMTP：邮件组件 IPVS

        wrapper：生成IPVS规则

        Netlink Reflector：网络接口

        WatchDog：监控进程

  • 控制组件：提供keepalived.conf 的解析器，完成Keepalived配置
  • IO复用器：针对网络目的而优化的自己的线程抽象
  • 内存管理组件：为某些通用的内存管理功能（例如分配，重新分配，发布等）提供访问权限

2.3 Keepalived 环境准备

2.3.1 ka1配置

[root@ka1 ~]# yum install keepalived.x86_64    -y
[root@ka1 ~]# systemctl start keepalived.service

[root@ka1 ~]# vim /etc/keepalived/keepalived.conf

2.3.2 ka2配置

[root@ka2 ~]# yum install keepalived.x86_64    -y
[root@ka2 ~]# systemctl start keepalived.service

2.3.3 测试

2.4 启用keepalived日志功能

[root@ka1 ~]# cat /etc/sysconfig/keepalivedKEEPALIVED_OPTIONS="-D -S 6"

[root@ka1 ~]# vim /etc/rsyslog.conf


[root@ka1 ~]# systemctl restart keepalived.service
[root@ka1 ~]# systemctl restart rsyslog.service

2.5 实现独立子配置文件

[root@ka1 ~]# mkdir /etc/keepalived/conf.d
[root@ka1 ~]# vim /etc/keepalived/keepalived.conf

三.Keepalived 企业应用示例

3.1 抢占模式和非抢占模式

默认为抢占模式preempt，即当高优先级的主机恢复在线后，会抢占低先级的主机的master角色， 这样会使vip在KA主机中来回漂移，造成网络抖动， 建议设置为非抢占模式 nopreempt ，即高优先级主机恢复后，并不会抢占低优先级主机的master角色 非抢占模块下,如果原主机down机, VIP迁移至的新主机, 后续也发生down时,仍会将VIP迁移回原主机

注意：要关闭 VIP抢占，必须将各 keepalived 服务器state配置为BACKUP

ka1 主机配置

[root@ka1 ~]# vim /etc/keepalived/conf.d/route.conf
[root@ka1 ~]# cat  /etc/keepalived/conf.d/route.conf
vrrp_instance VI_1 {state BACKUP                     #必须将keepalived服务器设置为backupinterface eth0virtual_router_id 100          priority 100                     #优先级高 nopreempt                        #非抢占模式advert_int 1authentication {auth_type PASSauth_pass 1111}virtual_ipaddress {172.25.254.100/24 dev eth0 label eth0:1}
}[root@ka1 ~]# systemctl restart keepalived.service

ka2配置

[root@ka2 ~]# vim /etc/keepalived/keepalived.confvrrp_instance VI_1 {state BACKUP                  #必须将keepalived服务器设置为backupinterface eth0virtual_router_id 100priority 80                   #低优先级advert_int 1nopreempt                     #非抢占模式authentication {auth_type PASSauth_pass 1111}virtual_ipaddress {172.25.254.100/24 dev eth0 label eth0:1}
}

3.2.2 抢占延迟模式 preempt_delay

抢占延迟模式，即优先级高的主机恢复后，不会立即抢回VIP，而是延迟一段时间（默认300s）再抢回 VIP

 preempt_delay #     
#指定抢占延迟时间为#s，默认延迟300s

注意：需要各keepalived服务器state为BACKUP,并且不要启用 vrrp_strict

ka1配置

ka2配置

测试

[root@ka1 ~]# watch -n 1 ifconfig

关闭ka1的keepalived后vip跳转到ka2

开启ka1后，vip不会立即跳回ka1，而是根据设置的延时抢占时间后抢占vip

3.3 VIP单播配置

默认keepalived主机之间利用多播相互通告消息，会造成网络拥塞，可以替换成单播，减少网络流量

注意：启用 vrrp_strict 时，不能启用单播

ka1配置

ka2配置

3.4 Keepalived 通知脚本配置

创建通知脚本

#!/bin/bash
mail_dest='1421304181@qq.com'mail_send()
{mail_subj='$HOSTNAME to be $1 vip move'mail_msg='`date +%F\ %T`:vrrp move $HOSTNAME chage $1'echo $mail_msg | mail -s "mail_sub" $mail_dst
}case $1 inmaster)send_message master;;backup)send_message backup;;fault)send_message fault;;*);;
esac

给执行权限

[root@ka1 ~]# chmod +x  /etc/keepalived/mail.sh

[root@ka1 ~]# yum install sendmail   #下载邮件服务器

添加邮件配置

[root@ka1 ~]# cat /etc/mail.rcset from=1421304181@qq.comset smtp=smtp.qq.comset smtp-auth-user=1421304181@qq.comset smtp-auth-password=fmgqbgkvyunaifciset smtp-auth=loginset ssl-verify=ignore

测试邮件

[root@ka1 ~]# echo tes | mail -s test 1421304181@qq.com

调用脚本：在 vrrp_instance VI_1 语句块的末尾加下面行

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

双主分别实现httpd和mysql服务的调度

在RS1和RS2中准备httpd和mysql环境在RS1中：
[root@rs1 ~]# ip addr add 172.25.254.200/32 dev lo[root@rs1 ~]# yum install mariadb-server  -yroot@rs1 ~]# vim /etc/my.cnfserver-id=1[root@rs1 ~]# systemctl enable --now mariadb[root@rs1 ~]# mysql -e "grant ALL on *.* to lee@'%' identified by 'lee'"[root@rs1 ~]# mysql -ulee -plee -h172.25.254.101 -e 'select @@server_id'+-------------+| @@server_id |+-------------+|           1 |+-------------+在RS2中：
[root@rs2 ~]# ip addr add 172.25.254.200/32 dev lo[root@rs2 ~]# yum install mariadb-server  -y[root@rs2 ~]# vim /etc/my.cnfserver-id=2[root@rs2 ~]# systemctl enable --now mariadb[root@rs2 ~]# mysql -e "grant ALL on *.* to lee@'%' identified by 'lee'"[root@rs2 ~]# mysql -ulee -plee -h172.25.254.102 -e 'select @@server_id'+-------------+| @@server_id |+-------------+|           1 |+-------------+

ka1配置

#配置双主模式
[root@rhel7-ka1 ~]# vim /etc/keepalived/keepalived.confvrrp_instance web {state MASTERinterface ens33virtual_router_id 100priority 100advert_int 1authentication {auth_type PASSauth_pass 1111}virtual_ipaddress {172.25.254.100 dev ens33 label ens33:0}}vrrp_instance sql {state BACKUPinterface ens33virtual_router_id 200priority 80advert_int 1authentication {auth_type PASSauth_pass 1111}virtual_ipaddress {172.25.254.200 dev ens33 label ens33:1}}include "/etc/keepalived/conf.d/web.conf"include "/etc/keepalived/conf.d/sql.conf"[root@rhel7-ka1 ~]# vim /etc/keepalived/conf.d/web.confvirtual_server 172.25.254.100 80 {delay_loop 6lb_algo wrrlb_kind DRprotocol TCPsorry_server 172.25.254.30 80real_server 172.25.254.101 80 {weight 1TCP_CHECK {connect_timeout 5nb_get_retry 3delay_before_retry 3connect_port 80}}real_server 172.25.254.102 80 {weight 1HTTP_GET {url {path /status_code 200}connect_timeout 1nb_get_retry 3delay_before_retry 1}}}[root@rhel7-ka1 ~]# vim /etc/keepalived/conf.d/sql.confvirtual_server 172.25.254.200 3306 {delay_loop 3lb_algo rrlb_kind DRprotocol TCPreal_server 172.25.254.101 3306 {weight 1TCP_CHECK {connect_timeout 5nb_get_retry 3delay_before_retry 3connect_port 3306}}real_server 172.25.254.102 3306 {weight 1TCP_CHECK {connect_timeout 5nb_get_retry 3delay_before_retry 3connect_port 3306}}}

ka2配置

[root@ka1 keepalived]# vim /etc/keepalived/keepalived.confvrrp_instance web {state BACKUP                #备机interface eth0virtual_router_id 50priority 80advert_int 1authentication {auth_type PASSauth_pass 1111}virtual_ipaddress {172.25.254.100 dev eth0 label eth0:1}}vrrp_instance sql {state MASTER            #主机interface eth0virtual_router_id 60priority 100advert_int 1authentication {auth_type PASSauth_pass 1111}virtual_ipaddress {172.25.254.200 dev eth0 label eth0:1}}include "/etc/keepalived/conf.d/web.conf"include "/etc/keepalived/conf.d/sql.conf"
[root@ka1 keepalived]#  vim /etc/keepalived/conf.d/web.confvirtual_server 172.25.254.100 80 {delay_loop 6lb_algo wrrlb_kind DRprotocol TCPsorry_server 172.25.254.30 80real_server 172.25.254.10 80 {weight 1TCP_CHECK {connect_timeout 5nb_get_retry 3delay_before_retry 3connect_port 80}}real_server 172.25.254.102 80 {weight 1HTTP_GET {url {path /status_code 200}connect_timeout 1nb_get_retry 3delay_before_retry 1}}}[root@rhel7-ka2 ~]# vim /etc/keepalived/conf.d/web.confvirtual_server 172.25.254.200 3306 {delay_loop 3lb_algo rrlb_kind DRprotocol TCPreal_server 172.25.254.101 3306 {weight 1TCP_CHECK {connect_timeout 5nb_get_retry 3delay_before_retry 3
connect_port 3306}}real_server 172.25.254.102 3306 {weight 1TCP_CHECK {connect_timeout 5nb_get_retry 3delay_before_retry 3connect_port 3306}}}

使用ipvsadm查看

[root@ka1 keepalived]#  ipvsadm -LnIP Virtual Server version 1.2.1 (size=4096)Prot LocalAddress:Port Scheduler Flags-> RemoteAddress:Port               Forward Weight ActiveConn InActConnTCP  172.25.254.100:80 wrr-> 172.25.254.100:80                  Route    1        0        0-> 172.25.254.101:80                  Route    1        0        0
TCP  172.25.254.200:3306 rr -> 172.25.254.101:3306                Route    1        0        0-> 172.25.254.102:3306                Route    1        0        0

测试

[root@ka1 keepalived]#  mysql -ulee -plee -h172.25.254.200 -e 'select @@server_id'+-------------+| @@server_id |+-------------+|           
2 |+-------------+
[root@ka2 keepalived]#  mysql -ulee -plee -h172.25.254.200 -e 'select @@server_id'+-------------+| @@server_id |+-------------+|           
1 |+-------------+
[root@ka1 keepalived]#  mysql -ulee -plee -h172.25.254.200 -e 'select @@server_id'

利用脚本实现主从角色切换

[root@ka1 keepalived]# vim /mnt/check_lee.sh#!/bin/bash[ ！ -f "/mnt/lee" ]
[root@ka1 keepalived]#  chmod  +x /mnt/check_lee.sh
[root@ka1 keepalived]# vim /etc/keepalived/keepalived.confvrrp_script check_lee {script "/mnt/check_lee.sh"interval 1weight -30fall 2rise 2timeout 2}vrrp_instance web {state MASTERinterface ens33virtual_router_id 50priority 100advert_int 1}authentication {auth_type PASSauth_pass 1111}virtual_ipaddress {172.25.254.100 dev ens33 label ens33:0}track_script {check_lee}
[root@ka1 keepalived]# touch /mnt/lee
[root@ka1 keepalived]# tail -f /var/log/messages


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