[高可用系列|keepalived]Nginx+keepalived架构

背景

         前面再说LNMT的架构中Nginx做负载均衡的时候，为了避免Nginx故障导致整体架构瘫痪，我们需要对Nginx做高可用处理，接下来就通过实验来感受一下！

 部署Keepalived

 1.        主备节点安装keepalived

root@xhz-uos:~# apt install -y keepalived
root@xhz-uos:~# 

2.     Master节点配置

#  拷贝配置模板

root@xhz-uos:/etc/keepalived# cp /usr/share/doc/keepalived/samples/keepalived.conf.vrrp ./
root@xhz-uos:/etc/keepalived# mv keepalived.conf.vrrp keepalived.conf


##修改配置
! Configuration File for keepalived

global_defs {
   notification_email {
     acassen
   }
   notification_email_from [email protected]
   smtp_server 192.168.65.129
   smtp_connect_timeout 30
   router_id keepalived-MASTER
}

vrrp_instance VI_1 {
    state MASTER
    interface ens33
    garp_master_delay 10
    smtp_alert
    virtual_router_id 51
    priority 100
    advert_int 1
    nopreempt
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.65.200

    }
}

3.     Backup节点配置 

##  拷贝配置模板
root@xhz-uos:/etc/keepalived# cp /usr/share/doc/keepalived/samples/keepalived.conf.vrrp ./
root@xhz-uos:/etc/keepalived# mv keepalived.conf.vrrp keepalived.conf


#配置文件
root@xhz-uos:/etc/keepalived# cat keepalived.conf 
! Configuration File for keepalived

global_defs {
   notification_email {
     acassen
   }
   notification_email_from [email protected]
   smtp_server 192.168.65.133
   smtp_connect_timeout 30
   router_id keepalived-backup
}

vrrp_instance VI_1 {
    state BACKUP
    interface ens33
    garp_master_delay 10
    smtp_alert
    virtual_router_id 51
    priority 90
    advert_int 1
    nopreempt
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.65.200

    }
}

4.     验证结果

 4.1        Master节点

 断开master的网络，vip切换至BACKUP节点。

 恢复MASTER节点的网络，vip又切回至Master

 配置非抢占模式：
1）两个节点的store都必须配置为BACKUP；
2）两个节点都在vrrp_instance中添加nopreempt；
3）其中一个节点的优先级必须高于另外一个节点优先级。

 地址漂移触发条件：
1）keepalived停止运行；
2）网关停止，（监听的网卡断网）；
3）无法检查到对方存活：  HTTP_GET|SSL_GET ：  用于应用层检测；脚本检测；TCP_CHECK|SMTP_CHECK|MISC_CHECK： 用于传输层检测

Keepalived  +  Nginx 

         配置LNMT架构：LNMT配置

 1.   配置Nginx

         两台Nginx配置一致

root@nginx:/etc/nginx/conf.d# cat tomcat.conf 
upstream tomcat_server {
    server 192.168.65.130:8080;
    server 192.168.65.131:8080;
}

server {
    listen 80;
    server_name zrlog.tomcat.com www.zrlog.tomcat.com;
    access_log  /var/log/nginx/zrlog.access.log  main;

    location / {
        proxy_pass http://tomcat_server;
        include proxy_params;
    }
}

2.   修改host解析

192.168.65.200  zrlog.tomcat.com www.zrlog.tomcat.com

 3.  访问测试

 3.1    关闭master上的Nginx服务

         此时vip没有漂移，LNMT访问错误。

 3.2    修改Keepalived配置文件

         通过自定义vrrp_script自定义检测脚本，来使得vip漂移。

####配置说明：
vrrp_script  {    #定义一个检测脚本，在global_defs之外配置
    script |    #shell命令或脚本路径
    interval                  #间隔时间，单位为秒，默认1秒
    timeout                   #超时时间
    weight          #此值为负数，表示fall（（脚本返回值为非0）时，会将此值与本节点权重相加可以降低本节点权重，如果是正数，表示 rise （脚本返回值为0）成功后，会将此值与本节点权重相加可以提高本节点权重，通常使用负值较多
    fall                      #脚本几次失败转换为失败，建议设为2以上
    rise                      #脚本连续监测成功后，把服务器从失败标记为成功的次数
    user USERNAME [GROUPNAME]          #执行监测脚本的用户或组
    init_fail                          #设置默认标记为失败状态，监测成功之后再转换为成功状态
}




###配置实例：
! Configuration File for keepalived

global_defs {
   notification_email {
     acassen
   }
   notification_email_from [email protected]
   smtp_server 192.168.65.129
   smtp_connect_timeout 30
   router_id keepalived-MASTER
}

vrrp_script check_nginx_server {
       script "/etc/keepalived/check_nginx.sh "
       interval 1
       weight -2
}


vrrp_instance VI_1 {
    state MASTER
    interface ens33
    garp_master_delay 10
    smtp_alert
    virtual_router_id 51
    priority 100
    advert_int 1
    nopreempt
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.65.200
    }
    
    track_script {
        check_nginx_server
    }
}

check_nginx_sererv脚本：脚本很简单，只是一个示例

#!/bin/bash
nginx_pid=`pidof nginx |wc -l`

if [ $nginx_pid == 0 ];then
    systemctl stop  keepalived
fi

 3.3    验证

 暂停129的nginx：

 VIP漂移：

 访问依然正常：