33.keepalived应用部署

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谨慎参考，图和原理抄过来的，只有实验是自己做的

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一、keepalived概述：

概述：keepalived起初为Lvs设计的一款强大的辅助工具，保证Lvs负载调度器的故障切换以及web节点的健康状态检查，后续被应用到很多需要容错的场景下，keepalived自身基于VRRP协议--虚拟路由冗余协议，思科公有协议；

二、设计原理：

应用场景：

设计模块：
1.core模块：为keepalived的核心组件，负责主进程的启动、维护以及全局配置文件的加载和解析；
2.check模块：负责real server 节点池内的节点的健康检测；
3.VRRP模块：在master与backup之间执行心跳检测；

热备实现过程：将多个主机以软件的方式组成一个热备组，通过共有的虚拟ip（VIP）地址对外提供服务，同一时刻，热备组中只有一台主机在工作，别的主机冗余状态，当当前在线的主机失效时，其他冗余的主机会自动接替虚拟ip地址，继续提供服务，以保证架构的稳定性；

 

三、案例：Keepalived实现双机热备；

案例拓扑：

案例环境：

系统类型	IP地址	主机名	所需软件
Centos 7.5 1804 64bit	10.0.3.49	node1	keepalived
Centos 7.5 1804 64bit	10.0.3.55	node2	keepalived

VIP：10.0.3.56

一、node1和node2安装httpd

[root@node1 ~]# yum install -y httpd
[root@node1 ~]# echo "<h1>node1<h1>" > /var/www/html/index.html
[root@node1 ~]# systemctl start httpd && systemctl enable httpd
[root@node1 ~]# ssh node2 "yum install -y httpd"
[root@node1 ~]# ssh node2 "echo '<h1>node2<h1>' > /var/www/html/index.html"
[root@node1 ~]# ssh node2 "systemctl start httpd && systemctl enable httpd"

二、安装keepalived

直接yum安装了，不使用源码编译安装

[root@node1 ~]# yum install -y keepalived.x86_64 
[root@node1 ~]# ssh node2 "yum install -y keepalived.x86_64"

三、在node1上配置master主节点

[root@node1 ~]# vim /etc/keepalived/keepalived.conf
[root@node1 ~]# cat /etc/keepalived/keepalived.conf 
! Configuration File for keepalived

global_defs {
    router_id TEST_R1        ##本服务器的名称，若环境中有多个keepalived时，此名称不能一致
}

vrrp_instance VI_1 {        ##定义VRRP热备实例，每一个keep组都不同
    state MASTER            ##MASTER表示主服务器
    interface ens33        ##承载VIP地址的物理接口
    virtual_router_id 51    ##虚拟路由器的ID号，每一个keep组都不同
    priority 100            ##优先级，数值越大优先级越高
    advert_int 1            ##通告检查间隔秒数（心跳频率）
    authentication {        ##认证信息
        auth_type PASS        ##认证类型
        auth_pass VVP3VU       ##密码字串
    }
    virtual_ipaddress {        ##指定漂移地址（VIP）
	10.0.3.56
    }
}

virtual_server 10.0.3.56 80 {    #vip配置
    delay_loop 6            #每隔6秒检查一次real_server状态
    lb_algo wrr            ##指定lvs的调度算法
    lb_kind DR            ##lvs集群模式
    persistence_timeout 50    ##会话保持时间
    protocol TCP            ##选择协议

    real_server 10.0.3.49 80 {    ##本机地址
        weight 3            ##服务器的权重
	notify_down /etc/keepalived/check.sh        ##指定节点失效后，采用的脚本，notify_up表示节点正常后，采用的脚本
        ##健康检查方式一共有HTTP_GET|SSL_GET|TCP_CHECK|SMTP_CHECK|MISC_CHECK这些
	TCP_CHECK{
	    connect_time 10        ##连接超时时间
	    nb_get_retry 3        ##重连次数
	    delay_before_retry 3    ##重连间隔时间
	    connect_port 80        ##健康检查端口
	}
    }
}

[root@node1 ~]# vim  /etc/keepalived/check.sh
#!/bin/bash
systemctl stop keepalived
echo -e "$(ip a |grep ens33 |grep inet |awk '{print $2}'|awk -F'/' '{print $1}') (httpd) is down on $(date +%F-%T)" >>/root/check_httpd.log
[root@node1 ~]# chmod 777 /etc/keepalived/check.sh 
[root@node1 ~]# systemctl start keepalived
[root@node1 ~]# ip a | grep 10.0.3.56
    inet 10.0.3.56/32 scope global ens33

四、在node2上配置backup节点

[root@node2 ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived

global_defs {
	router_id TEST_R2        ##本服务器的名称
}

vrrp_instance VI_1 {        
    state BACKUP            ##BACKUP表示从服务器
    interface ens33
    virtual_router_id 99    ##优先级，低于主服务器
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass VVP3VU
    }
    virtual_ipaddress {
	10.0.3.56
    }
}

virtual_server 10.0.3.56 80 {    ##vip配置
    delay_loop 6            ##每隔6秒检查一次real_server状态
    lb_algo wrr
    lb_kind DR
    persistence_timeout 50    ##会话保持时间
    protocol TCP

    real_server 10.0.3.56 80 {    ##本机地址
        weight 3
	notify_down /etc/keepalived/check.sh
	TCP_CHECK{
	    connect_timeout 10     ##连接超时时间
	    nb_get_retry 3        ##重连次数
	    delay_before_retry 3     ##重连间隔时间
	    connect_port 80        ##健康检查端口
	}
    }
}

[root@node2 ~]# vim /etc/keepalived/check.sh
[root@node2 ~]# cat /etc/keepalived/check.sh 
#!/bin/bash
systemctl stop keepalived
echo -e "$(ip a |grep ens33 |grep inet |awk '{print $2}'|awk -F'/' '{print $1}') (httpd) is down on $(date +%F-%T)" >>/root/check_httpd.log
[root@node2 ~]# chmod 777 /etc/keepalived/check.sh 
[root@node2 ~]# systemctl start keepalived.service 
[root@node2 ~]# ip a | grep 10.0.3.56
    inet 10.0.3.56/32 scope global ens33

五、客户端访问：

六、node1挂掉

[root@node1 ~]# systemctl stop httpd
[root@node1 ~]# systemctl status keepalived.service 
● keepalived.service - LVS and VRRP High Availability Monitor
   Loaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled; vendor preset: disabled)
   Active: inactive (dead)

1月 25 16:33:35 node1 Keepalived_healthcheckers[4626]: TCP connection to [10.0.3.49]:80 failed.
1月 25 16:33:35 node1 Keepalived_healthcheckers[4626]: Check on service [10.0.3.49]:80 failed after 1 retry.
1月 25 16:33:35 node1 Keepalived_healthcheckers[4626]: Removing service [10.0.3.49]:80 from VS [10.0.3.56]:80
1月 25 16:33:35 node1 Keepalived_healthcheckers[4626]: Executing [/etc/keepalived/check.sh] for service [10.0.3.49]:80 in VS...6]:80
1月 25 16:33:35 node1 Keepalived_healthcheckers[4626]: Lost quorum 1-0=1 > 0 for VS [10.0.3.56]:80
1月 25 16:33:35 node1 Keepalived[4625]: Stopping
1月 25 16:33:35 node1 systemd[1]: Stopping LVS and VRRP High Availability Monitor...
1月 25 16:33:35 node1 Keepalived_vrrp[4627]: VRRP_Instance(VI_1) sent 0 priority
1月 25 16:33:35 node1 Keepalived_vrrp[4627]: VRRP_Instance(VI_1) removing protocol VIPs.
1月 25 16:33:36 node1 systemd[1]: Stopped LVS and VRRP High Availability Monitor.
Hint: Some lines were ellipsized, use -l to show in full.

七、将node1的httpd和keepalived开启

[root@node1 ~]# systemctl start httpd
[root@node1 ~]# systemctl start keepalived