keepalived高可用

Keepalived主要用于实现LVS负载均衡和系统服务的高可用,借助VRRP协议进行故障切换。当主节点故障时,备节点接管IP资源,确保业务连续性。本文介绍了Keepalived的重要功能、VRRP协议以及部署步骤。

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keepalived简介

Keepalived 软件起初是专为LVS负载均衡软件设计的,用来管理并监控LVS集群系统中各个服务节点的状态,后来又加入了可以实现高可用的VRRP功能。因此,Keepalived除了能够管理LVS软件外,还可以作为其他服务(例如:Nginx、Haproxy、MySQL等)的高可用解决方案软件。
Keepalived软件主要是通过VRRP协议实现高可用功能的。VRRP是Virtual Router RedundancyProtocol(虚拟路由器冗余协议)的缩写,VRRP出现的目的就是为了解决静态路由单点故障问题的,它能够保证当个别节点宕机时,整个网络可以不间断地运行。
所以,Keepalived 一方面具有配置管理LVS的功能,同时还具有对LVS下面节点进行健康检查的功能,另一方面也可实现系统网络服务的高可用功能。
Keepalived官网

Keepalived的重要功能

keepalived 有三个重要的功能,分别是:
(1)管理LVS负载均衡软件
(2)实现LVS集群节点的健康检查
(3)作为系统网络服务的高可用性

3、keepalived高可用故障转移的原理
Keepalived 高可用服务之间的故障切换转移,是通过 VRRP (Virtual Router Redundancy Protocol ,虚拟路由器冗余协议)来实现的。
在 Keepalived 服务正常工作时,主 Master 节点会不断地向备节点发送(多播的方式)心跳消息,用以告诉备 Backup 节点自己还活看,当主 Master 节点发生故障时,就无法发送心跳消息,备节点也就因此无法继续检测到来自主 Master 节点的心跳了,于是调用自身的接管程序,接管主 Master 节点的 IP 资源及服务。而当主 Master 节点恢复时,备 Backup 节点又会释放主节点故障时自身接管的IP资源及服务,恢复到原来的备用角色。

keepalived原理

在这里插入图片描述
Keepalived高可用对之间是通过VRRP通信的,因此,我们从 VRRP开始了解起:
(1) VRRP,全称 Virtual Router Redundancy Protocol,中文名为虚拟路由冗余协议,VRRP的出现是为了解决静态路由的单点故障。
(2)VRRP是通过一种竟选协议机制来将路由任务交给某台 VRRP路由器的。
(3)VRRP用 IP多播的方式(默认多播地址(224.0.0.18))实现高可用对之间通信。
(4)工作时主节点发包,备节点接包,当备节点接收不到主节点发的数据包的时候,就启动接管程序接管主节点的资源。备节点可以有多个,通过优先级竞选,但一般 Keepalived系统运维工作中都是一对。
(5)VRRP使用了加密协议加密数据,但Keepalived官方目前还是推荐用明文的方式配置认证类型和密码。
介绍完 VRRP,接下来我再介绍一下 Keepalived服务的工作原理:
Keepalived高可用是通过 VRRP 进行通信的, VRRP是通过竞选机制来确定主备的,主的优先级高于备,因此,工作时主会优先获得所有的资源,备节点处于等待状态,当主挂了的时候,备节点就会接管主节点的资源,然后顶替主节点对外提供服务。
在 Keepalived 服务之间,只有作为主的服务器会一直发送 VRRP 广播包,告诉备它还活着,此时备不会枪占主,当主不可用时,即备监听不到主发送的广播包时,就会启动相关服务接管资源,保证业务的连续性.接管速度最快可以小于1秒。

keepalived部署

主机名IP系统
MasterIP:192.168.40.99 --VIP: 192.168.40.111rhel8/centos8
SlaveIP:192.168.40.100rhel8/centos8

Master主节点和slave备份节点

关闭防火墙和selinux
systemctl stop firewalld
systemctl disable firewalld
cat /etc/sysconfig/selinux 
SELINUX=disabled
配置yum源--阿里源centos8和epel源
wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-vault-8.5.2111.repo
yum install -y https://mirrors.aliyun.com/epel/epel-release-latest-8.noarch.rpm
sed -i 's|^#baseurl=https://download.example/pub|baseurl=https://mirrors.aliyun.com|' /etc/yum.repos.d/epel*
sed -i 's|^metalink|#metalink|' /etc/yum.repos.d/epel*
安装一下常用命令
dnf -y install gcc gcc-c++
安装keepalived
dnf -y install keepalived

在master节点安装nginx

[root@Master ~]# dnf -y install nginx
[root@Master ~]# systemctl restart nginx.service 
[root@Master ~]# systemctl enable nginx.service 
Created symlink /etc/systemd/system/multi-user.target.wants/nginx.service → /usr/lib/systemd/system/nginx.service.
在nginx中添加测试网页
[root@Master ~]# cd /usr/share/nginx/html/
[root@Master html]# ls
404.html  50x.html  index.html  nginx-logo.png  poweredby.png
[root@Master html]# echo 'hi Master' > index.html

在slave节点安装nginx

[root@Slave ~]# systemctl restart nginx.service 
[root@Slave ~]# systemctl enable nginx.service 
Created symlink /etc/systemd/system/multi-user.target.wants/nginx.service → /usr/lib/systemd/system/nginx.service.
[root@Slave ~]# dnf -y install nginx
在nginx中添加测试网页
[root@Slave ~]# cd /usr/share/nginx/html/
[root@Slave html]# ls
404.html  50x.html  index.html  nginx-logo.png  poweredby.png
[root@Slave html]# echo "hi Slave" > index.html 

在这里插入图片描述
在这里插入图片描述
配置主keepalived

例子:
at keepalived.conf   //查看配置文件
! Configuration File for keepalived

global_defs {              //全局配置
   notification_email {     //定义报警收件人邮件地址
     acassen@firewall.loc
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from Alexandre.Cassen@firewall.loc   //定义报警发件人邮箱
   smtp_server 192.168.200.1    //邮箱服务器地址
   smtp_connect_timeout 30     //定义邮箱超时时间
   router_id LVS_DEVEL         //定义路由标识信息,同局域网内唯一
   vrrp_skip_check_adv_addr
   vrrp_strict
   vrrp_garp_interval 0
   vrrp_gna_interval 0
}

vrrp_instance VI_1 {           //定义实例
    state MASTER           //指定keepalived节点的初始状态,可选值为MASTER/BACKUP
    interface eth0       //VRRP实例绑定的网卡接口,用户发送VRRP包
    virtual_router_id 51  //虚拟路由的ID,同一集群要一致
    priority 100   //定义优先级,按优先级来决定主备角色,优先级越大越优先
    advert_int 1  //主备通讯时间间隔
    authentication {       //配置认证
        auth_type PASS   //认证方式,此处为密码
        auth_pass 1111   //同一集群中的keepalived配置里此处必须一致,推荐使用8为随机数
    }
    virtual_ipaddress {         //配置要使用的VIP
        192.168.200.16
        192.168.200.17
        192.168.200.18
    }
}

virtual_server 192.168.200.100 443 {       //配置虚拟服务器
    delay_loop 6                 //健康检查的时间间隔
    lb_algo rr                    //lvs调度算法
    lb_kind NAT                 //lvs模式
    persistence_timeout 50       //持久化超时时间,单位为秒
    protocol TCP               //4层协议

sorry_server  192.168.200.200 1358 //定义备用服务器,当所有RS都故障时,用sorry_server来响应客户端

    real_server 192.168.201.100 443 {   //定义真是处理请求的服务器
        weight 1        //给服务器指定权重,默认为1
        SSL_GET {
            url {
              path /         //指定要检查的URL路径
              digest ff20ad2481f97b1754ef3e12ecd3a9cc     //摘要信息
            }
            url {
              path /mrtg/
              digest 9b3a0c85a887a256d6939da88aabd8cd
            }
            connect_timeout 3       //连接超时时间
            retry 3             //get尝试次数
            delay_before_retry 3   //在尝试之前延迟多长时间
        }
    }
}
  real_server 192.168.100.100 80 {
        weight 1
        TCP_CHECK {
	        connect_port 80   //连接端口
            connect_timeout 3  //连接超时时间,默认为5秒
	        nb_get_retry 3
            delay_before_retry 3   //在重试之前延迟多少秒
[root@Master ~]# cd /etc/keepalived/
[root@Master keepalived]# cp keepalived.conf keepalived.conf.bak
[root@Master keepalived]# vim keepalived.conf
! Configuration File for keepalived

global_defs {
   router_id haha
}

vrrp_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.40.111
    }
}

virtual_server 192.168.40.111 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP

    real_server 192.168.40.99 80 {
        weight 1
        TCP_CHECK {
	    connect_port 80
            connect_timeout 3
	    nb_get_retry 3
            delay_before_retry 3
        }
    }


    real_server 192.168.40.100 80 {
        weight 1
        TCP_CHECK { 
	    connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}

重启服务并设置下次启动生效

[root@Master keepalived]# systemctl restart keepalived.service 
[root@Master keepalived]# systemctl enable keepalived.service 
Created symlink /etc/systemd/system/multi-user.target.wants/keepalived.service → /usr/lib/systemd/system/keepalived.service.

在slave节点配置备份keepalived

[root@Slave ~]# cd /etc/keepalived/
[root@Slave keepalived]# cp keepalived.conf keepalived.conf.bak
[root@Slave keepalived]# vim keepalived.conf
! Configuration File for keepalived

global_defs {
   router_id hehe
}

vrrp_instance VI_1 {
    state BACKUP
    interface ens33
    virtual_router_id 51
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.40.111
    }
}

virtual_server 192.168.40.111 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP

    real_server 192.168.40.99 80 {
        weight 1
        TCP_CHECK {
	    connect_port 80
            connect_timeout 3
	    nb_get_retry 3
            delay_before_retry 3
        }
    }


    real_server 192.168.40.100 80 {
        weight 1
        TCP_CHECK { 
	    connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}

重启服务并设置下次启动生效

[root@Slave keepalived]# systemctl restart keepalived.service 
[root@Slave keepalived]# systemctl enable keepalived.service 
Created symlink /etc/systemd/system/multi-user.target.wants/keepalived.service → /usr/lib/systemd/system/keepalived.service.

在master中配置VIP

[root@Master ~]# ip addr add 192.168.40.111/32 dev ens33 
root@Master ~]# ip addr show ens33 
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:0c:29:a3:51:0a brd ff:ff:ff:ff:ff:ff
    inet 192.168.40.99/24 brd 192.168.40.255 scope global noprefixroute ens33
       valid_lft forever preferred_lft forever
    inet 192.168.40.111/32 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fea3:510a/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

修改内核参数,开启侦听VIP功能
此步可做可不做,该功能可用于仅监听VIP的时候
Master和slave

vim /etc/sysctl.conf
net.ipv4.ip_nonlocal_bind = 1

sysctl -p
net.ipv4.ip_nonlocal_bind = 1

让keepalived监控nginx负载均衡
在master上编写脚本

[root@Master ~]# mkdir /scripts
[root@Master ~]# cd /scripts/
[root@Master scripts]# vim check.sh
[root@Master scripts]# cat check.sh 
#!/bin/bash
nginx_status=`ps -ef | grep -v "grep" | grep "nginx" | wc -l`
if [ $nginx_status -lt 1 ];then
        systemctl stop keepalived
fi

[root@Master scripts]# chmod +x check.sh 
[root@Master scripts]# vim notify.sh
[root@Master scripts]# cat notify.sh 
#!/bin/bash
VIP=$2
sendmail () { 
	subject="${VIP}'s server keepalived state is translate"
	content="`date +'%F %T'`: `hostname`'s state change to master"
	echo $content | mail -s "$subject" haha@example.com
}
case "$1" in 
  master)
	nginx_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bnginx\b'|wc -l)
	if [ $nginx_status -lt 1 ];then
		systemctl start nginx
	fi
	sendmail
   ;;
   backup)								        
	nginx_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bnginx\b'|wc -l)
	if [ $nginx_status -gt 0 ];then
		systemctl stop nginx
	fi
   ;;
   *) 
	echo "Usage:$0 master|backup VIP"
   ;;
esac

[root@Master scripts]# chmod +x notify.sh 

在slave上编写脚本

[root@Slave ~]# mkdir /scripts
[root@Slave ~]# cd /scripts/
[root@Slave scripts]# scp -r root@192.168.40.99:/scripts/* .
root@192.168.40.99's password: 
check.sh                                                             100%  144   198.3KB/s   00:00    
notify.sh                                                            100%  595   914.7KB/s   00:00    
[root@Slave scripts]# ll
总用量 8
-rwxr-xr-x. 1 root root 144 10月  8 01:18 check.sh
-rwxr-xr-x. 1 root root 595 10月  8 01:18 notify.sh

配置master的keepalived

[root@Master keepalived]# cat keepalived.conf
[root@Master keepalived]# cat keepalived.conf
! Configuration File for keepalived

global_defs {
   router_id haha
}

vrrp_script nginx_check { 
    script "/scripts/check.sh"
    interval 10
    weight -20
}

vrrp_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.40.111
    }
    track_script { 
    nginx_check
    }
    notify_master "/scripts/notify.sh master 192.168.40.111"
    notify_backup "/scripts/notify.sh backup 192.168.40.111"
}

virtual_server 192.168.40.111 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP

    real_server 192.168.40.99 80 {
        weight 1
        TCP_CHECK {
	    connect_port 80
            connect_timeout 3
	    nb_get_retry 3
            delay_before_retry 3
        }
    }


    real_server 192.168.40.100 80 {
        weight 1
        TCP_CHECK { 
	    connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}
[root@Master keepalived]# systemctl restart keepalived.service 

配置slave的keepalived

[root@Slave keepalived]# cat keepalived.conf
! Configuration File for keepalived

global_defs {
   router_id hehe
}

vrrp_instance VI_1 {
    state BACKUP
    interface ens33
    virtual_router_id 51
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.40.111
    }
    notify_master "/scripts/notify.sh master 192.168.40.111"
    notify_backup "/scripts/notify.sh backup 192.168.40.111"
}


virtual_server 192.168.40.111 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP

    real_server 192.168.40.99 80 {
        weight 1
        TCP_CHECK {
	    connect_port 80
            connect_timeout 3
	    nb_get_retry 3
            delay_before_retry 3
        }
    }


    real_server 192.168.40.100 80 {
        weight 1
        TCP_CHECK { 
	    connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}
[root@Slave keepalived]# systemctl restart keepalived.service 

模拟故障
启用keepalived,开启nginx服务

[root@Master ~]# systemctl restart keepalived.service 
[root@Master ~]# systemctl enable keepalived.service 
[root@Master ~]# systemctl restart nginx.service 
[root@Master ~]# systemctl enable nginx.service

在slave中查看端口80是否开启

[root@Slave keepalived]# ss -antlp
State        Recv-Q       Send-Q              Local Address:Port               Peer Address:Port       Process                                                                                                
LISTEN       0            128                       0.0.0.0:111                     0.0.0.0:*           users:(("rpcbind",pid=912,fd=4),("systemd",pid=1,fd=40))                                              
LISTEN       0            32                  192.168.122.1:53                      0.0.0.0:*           users:(("dnsmasq",pid=1816,fd=6))                                                                     
LISTEN       0            128                       0.0.0.0:22                      0.0.0.0:*           users:(("sshd",pid=1000,fd=4))                                                                        
LISTEN       0            5                       127.0.0.1:631                     0.0.0.0:*           users:(("cupsd",pid=1163,fd=10))                                                                      
LISTEN       0            128                          [::]:111                        [::]:*           users:(("rpcbind",pid=912,fd=6),("systemd",pid=1,fd=42))                                              
LISTEN       0            128                          [::]:22                         [::]:*           users:(("sshd",pid=1000,fd=6))                                                                        
LISTEN       0            5                           [::1]:631                        [::]:*           users:(("cupsd",pid=1163,fd=9))            

在这里插入图片描述
关闭master的nginx服务
[root@Master scripts]# systemctl stop nginx
在slave中查看端口80是否开启

[root@Slave keepalived]# ss -antlp
State        Recv-Q       Send-Q              Local Address:Port               Peer Address:Port       Process                                                                                                
LISTEN       0            128                       0.0.0.0:111                     0.0.0.0:*           users:(("rpcbind",pid=912,fd=4),("systemd",pid=1,fd=40))                                              
LISTEN       0            128                       0.0.0.0:80                      0.0.0.0:*           users:(("nginx",pid=2892,fd=8),("nginx",pid=2891,fd=8),("nginx",pid=2890,fd=8))                       
LISTEN       0            32                  192.168.122.1:53                      0.0.0.0:*           users:(("dnsmasq",pid=1816,fd=6))                                                                     
LISTEN       0            128                       0.0.0.0:22                      0.0.0.0:*           users:(("sshd",pid=1000,fd=4))                                                                        
LISTEN       0            5                       127.0.0.1:631                     0.0.0.0:*           users:(("cupsd",pid=1163,fd=10))                                                                      
LISTEN       0            128                          [::]:111                        [::]:*           users:(("rpcbind",pid=912,fd=6),("systemd",pid=1,fd=42))                                              
LISTEN       0            128                          [::]:80                         [::]:*           users:(("nginx",pid=2892,fd=9),("nginx",pid=2891,fd=9),("nginx",pid=2890,fd=9))                       
LISTEN       0            128                          [::]:22                         [::]:*           users:(("sshd",pid=1000,fd=6))                                                                        
LISTEN       0            5                           [::1]:631                        [::]:*           users:(("cupsd",pid=1163,fd=9))                                                              

在这里插入图片描述

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