keepalived安装部署

作者: 吃可爱长大鸭 | 来源:发表于2019-10-16 10:49 被阅读0次

keepalived介绍

VRRP协议
目的就是为了解决静态路由单点故障问题的

第二章： keepalived工作原理

keepalived高可用功能实现的基本原理为:

两台主机同时安装好keepalived软件并启动服务,开始正常工作时
角色为Master的主机获得所有资源并对用户提供服务
角色为Backup的主机作为Master主机的热备;

当角色为Master的主机失效或出现故障时
角色为Backup的主机将自动接管Master主机的所有工作,包括接管VIP资源及相应资源服务

而当角色为Master的主机故障修复后,又会自动接管回他原来处理的工作
角色为Backup的主机则同时释放Master主机失效时他接管的工作
此时,两台主机将恢复到启动时各自的原始角色及工作状态

第三章： VRRP协议

VRRP通过竞选机制来实现虚拟路由器的功能
所有的协议报文都是通过IP多播(Multicast)包
默认的多播地址224.0.0.18

VIP前提条件：

1.虚拟公网IP必须是真实可用的
2.虚拟公网IP不能重复
3.虚拟公网IP必须和相同网段的物理网卡绑定
4.组播地址必须是可以通讯的

第四章：keepalived安装配置
1.安装keepalived

yum install keepalived -y

2.配置文件解释

global_defs {               
    router_id lb01          #设置路由ID，每个主机不一样
}   

vrrp_instance VI_1 {        #设置VRRP组名，同一组组名相同
    state MASTER            #设置角色状态，分为MASTER BACKUP
        interface eth0      #VIP绑定的网卡
        virtual_router_id 50    #虚拟路由id，同一组一样
        priority 150        #权重，权重越高，优先级越高
        advert_int 1        #发送组播间隔
        authentication {    #设置验证，密码为明文
            auth_type PASS  
            auth_pass 1111  
        }
        virtual_ipaddress { #设定的虚拟IP，这个虚拟IP必须是存在且合法且没有被使用的。
            10.0.0.3
        }
}

3.lb01配置

[root@lb01 ~]# cat /etc/keepalived/keepalived.conf 
global_defs {
    router_id lb01
}

vrrp_instance VI_1 {
    state MASTER
        interface eth0
        virtual_router_id 50
        priority 150
        advert_int 1
        authentication {
            auth_type PASS
            auth_pass 1111
        }
        virtual_ipaddress {
            10.0.0.3
        }
}

4.lb02配置

[root@lb02 ~]# cat /etc/keepalived/keepalived.conf 
global_defs {
    router_id lb02
}

vrrp_instance VI_1 {
    state BACKUP 
        interface eth0
        virtual_router_id 50
        priority 100
        advert_int 1
        authentication {
            auth_type PASS
            auth_pass 1111
        }
        virtual_ipaddress {
            10.0.0.3
        }
}

5.启动

systemctl start keepalived

6.测试

关掉任意一台，观察VIP是否会漂移
恢复MASTER观察BACKUP的VIP是否会消失

第五章：脑裂现象
实验现象：
1.安装抓包工具

yum install tcpdump -y

2.lb02抓包查看

tcpdump -nn -i any host 224.0.0.18

3.lb02新开一个终端，然后开启防火墙

systemctl start firewalld.service

4.lb02观察抓包现象
观察是否两边都有VIP

5.添加放行规则

firewall-cmd --direct --permanent --add-rule ipv4 filter INPUT 0 --in-interface eth0 --destination 224.0.0.18 --protocol vrrp -j ACCEPT
firewall-cmd --direct --permanent --add-rule ipv4 filter INPUT 0 --in-interface eth1 --destination 224.0.0.18 --protocol vrrp -j ACCEPT
systemctl reload firewalld

6.lb02观察抓包现象
观察是否两边都有VIP

第六章：keepalived双主实验

1.lb01配置文件

[root@lb01 ~]# cat /etc/keepalived/keepalived.conf 
global_defs {
    router_id lb01
}

vrrp_instance VI_1 {
    state MASTER
        interface eth0
        virtual_router_id 50
        priority 150
        advert_int 1
        authentication {
            auth_type PASS
            auth_pass 1111
        }
        virtual_ipaddress {
            10.0.0.3
        }
}

vrrp_instance VI_2 {
    state BACKUP 
        interface eth0
        virtual_router_id 51
        priority 100
        advert_int 1
        authentication {
            auth_type PASS
            auth_pass 2222 
        }
        virtual_ipaddress {
            10.0.0.4
        }
}

2.lb02配置文件

[root@lb02 ~]# cat /etc/keepalived/keepalived.conf 
global_defs {
    router_id lb02
}

vrrp_instance VI_1 {
    state BACKUP 
        interface eth0
        virtual_router_id 50
        priority 100
        advert_int 1
        authentication {
            auth_type PASS
            auth_pass 1111
        }
        virtual_ipaddress {
            10.0.0.3
        }
}

vrrp_instance VI_2 {
    state MASTER 
        interface eth0
        virtual_router_id 51
        priority 150
        advert_int 1
        authentication {
            auth_type PASS
            auth_pass 2222 
        }
        virtual_ipaddress {
            10.0.0.4
        }
}

3.重启keepalived并观察现象

systemctl restart keepalived

第七章：keepalived结合nginx反向代理负载均衡

lb服务器的Nginx配置：
注意！两台lb服务器的Nginx配置一模一样

1.备份原有配置

mkdir /backup
cd /etc/nginx/conf.d
mv * /backup

2.编写Nginx配置文件

[root@lb01 /etc/nginx/conf.d]# cat proxy.conf 
upstream web_pools {
   server 172.16.1.7;
   server 172.16.1.8;
}

server {
   listen 80;
   server_name  (www|bbs).mysun.com ;
   location / {
      proxy_pass  http://web_pools;
      include proxy_params;
   }
}

3.测试并重启nginx

nginx -t
systemctl restart nginx

lb服务器的keepalived配置：

1.lb01的keepalived配置

[root@lb01 ~]# cat /etc/keepalived/keepalived.conf 
global_defs {
    router_id lb01
}

vrrp_instance VI_1 {
    state MASTER
        interface eth0
        virtual_router_id 50
        priority 150
        advert_int 1
        authentication {
            auth_type PASS
            auth_pass 1111
        }
        virtual_ipaddress {
            10.0.0.3
        }
}

2.lb02的keepalived配置

[root@lb02 ~]# cat /etc/keepalived/keepalived.conf 
global_defs {
    router_id lb02
}

vrrp_instance VI_1 {
    state BACKUP 
        interface eth0
        virtual_router_id 50
        priority 100
        advert_int 1
        authentication {
            auth_type PASS
            auth_pass 1111
        }
        virtual_ipaddress {
            10.0.0.3
        }
}

web服务器配置：
注意！两台web服务器配置一模一样
1.nginx配置

[root@web01 ~]# cat /etc/nginx/conf.d/www.conf 
server {
  listen 80;
  server_name www.mysun.com;
  location / {
     root /code;
     index www.html;
  }
}

2.写入测试文件

echo "$(hostname)" >/code/index.html

第八章：防裂脑脚本
问题现象：

1.nginx挂了，但是keep还活着
2.两边都有VIP

思路：
解决nginx挂了问题：
1.编写一个脚本

启动nginx
如果启动2次都失败了，停掉自己的keepalived

2.keepalived定时去调用这个脚本

实现：
1.命令如何实现

systemctl start nginx

2.检查nginx进程

[root@lb01 ~]# ps -ef|grep nginx|grep -v "grep"
root       1210      1  0 11:21 ?        00:00:00 nginx: master process /usr/sbin/nginx -c /etc/nginx/nginx.conf
nginx      1211   1210  0 11:21 ?        00:00:00 nginx: worker process

[root@lb01 ~]# ps -ef|grep nginx|grep -v "grep"|wc -l
2

[root@lb01 ~]# ps -ef|grep nginx|grep -v "grep"|wc -l
0

脚本内容：

[root@lb01 ~]# cat check_web.sh 
[root@lb01 ~]# cat check_web.sh 
#!/bin/bash

nginx_status=$(ps -C nginx --no-header|wc -l)

if [[ ${nginx_status} == 0 ]]
then
   systemctl start nginx &> /dev/null 
   sleep 1
   nginx_status=$(ps -C nginx --no-header|wc -l)
   if [[ ${nginx_status} == 0 ]]
   then
       systemctl stop keepalived  
   fi
fi


keepalived调用脚本：
[root@lb01 ~]# cat /etc/keepalived/keepalived.conf 
global_defs {
    router_id lb01
}

vrrp_script check_web {
    script "/server/scripts/check_web.sh"
    interval 5
    weight 50
}

vrrp_instance VI_1 {
    state MASTER
        interface eth0
        virtual_router_id 50
        priority 150
        advert_int 1
        authentication {
            auth_type PASS
            auth_pass 1111
        }
        virtual_ipaddress {
            10.0.0.3
        }

    track_script {
        check_web
    }
}

第二个问题：脑裂问题
两边都有VIP

现象：
2边都有VIP
2边Nginx都活着

对面的MASTER的Nginx还活着

curl -I -s -w "%{http_code}\n" -o /dev/null 10.0.0.5

但是我又有了VIP

ip a |grep "10.0.0.3"|wc -l

我就把自己干掉

systemctl stop nginx  
systemctl stop keepalived

脚本内容：

[root@lb02 /server/scripts]# cat check_vip.sh 
#!/bin/bash

master_status=$(curl -I -s -w "%{http_code}\n" -o /dev/null 10.0.0.5)

my_vip=$(ip a |grep "10.0.0.3"|wc -l)

if [ ${master_status} == 200 -a ${my_vip} == 1 ]
then
   systemctl stop nginx  
   systemctl stop keepalived 
fi

keepalived配置：

[root@lb02 ~]# cat /etc/keepalived/keepalived.conf 
global_defs {
    router_id lb02
}

vrrp_script check_web {
    script "/server/scripts/check_web.sh"
    interval 5
    weight 50
}

vrrp_script check_vip {
    script "/server/scripts/check_vip.sh"
    interval 5
    weight 50
}

vrrp_instance VI_1 {
    state BACKUP 
        interface eth0
        virtual_router_id 50
        priority 100
        advert_int 1
        authentication {
            auth_type PASS
            auth_pass 1111
        }
        virtual_ipaddress {
            10.0.0.3
        }

    track_script {
        check_web
        check_vip
    }
}

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