nginx实现请求的负载均衡 + keepalived实现nginx的高可用

浅浅的花香味﹌ 2023-01-18 12:27 55阅读 0赞

`简介`
    Keepalived是Linux下一个轻量级别的高可用解决方案。Keepalived的作用是检测服务器的状态，如果有一台web服务器宕机，或工作出现故障，Keepalived将检测到，并将有故障的服务器从系统中剔除，同时使用其他服务器代替该服务器的工作，当服务器工作正常后Keepalived自动将服务器加入到服务器群中，这些工作全部自动完成，不需要人工干涉，需要人工做的只是修复故障的服务器。
    `重要功能`
    管理LVS负载均衡软件
    实现LVS集群节点的健康检查中
    作为系统网络服务的高可用性
    `高可用故障切换原理`
    Keepalived高可用服务对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。

`1、环境准备`

172.18.62.38      nginx+keeplived   master
    172.18.62.39      nginx+keeplived   backup
    172.18.62.40      apache
    172.18.62.41      apache
    172.18.62.42      vip

`2、启动容器`

[root@iZuf612i9bshiuw3zzlfe9Z keeplived]# docker ps 
    CONTAINER ID        IMAGE                       COMMAND                  CREATED              STATUS              PORTS                    NAMES
    a2405e53d1d2        kad                         "/usr/sbin/init"         About a minute ago   Up About a minute                            keepalived_apache1_1
    7967b49e3930        kad                         "/usr/sbin/init"         About a minute ago   Up About a minute   0.0.0.0:100->80/tcp      keepalived_vip_1
    ade36b938d94        kad                         "/usr/sbin/init"         About a minute ago   Up About a minute                            keepalived_apache2_1
    1d3af026ed63        kad                         "/usr/sbin/init"         About a minute ago   Up About a minute   0.0.0.0:80->80/tcp       keepalived_nginx-master_1
    7a739f103336        kad                         "/usr/sbin/init"         About a minute ago   Up About a minute   0.0.0.0:90->80/tcp       keepalived_nginx-slave_1

`3、安装服务apache`

#更新软件包
    apt update
    apt upgrade -y
    #安装apache
    apt install apache2 -y
    #方便测试，修改首页
    vim /var/www/html/index.html
    #启动apache服务
    /etc/init.d/apache2 start

访问如下：
    root@apache1:/var/www/html# curl http://172.18.62.40
    <h1>Apache1 172.18.62.40</h1>
    root@apache2:/var/www/html# curl http://172.18.62.41
    <h1>Apache2 172.18.62.41</h1>

`4、安装nginx`

#下载安装包
    wget -P /usr/local/ http://nginx.org/download/nginx-1.2.8.tar.gz
    #安装依赖
    apt-get install libpcre3 libpcre3-dev zlib1g-dev -y
    #解压
    tar xvf nginx-1.2.8.tar.gz
    安装
    ./configure
    make CFLAGS='-Wno-implicit-fallthrough'
    make install

`5、安装keepalived`

#更新安装包
    apt update
    apt upgrade -y
    #安装服务
    apt install keepalived -y

`6、配置nginx`

vim /usr/local/nginx/conf/nginx.conf
    #负载均衡配置
    upstream web{ 
            server 172.18.62.40:80 weight=1;
            server 172.18.62.41:80 weight=1;
    }
    #server配置
    server { 
            listen       80;
            server_name  localhost;
    
            location / { 
                proxy_pass http://web;
            }
    }
    #启动nginx
    /usr/local/nginx/sbin/nginx

`7、配置keepalived`

vim /etc/keepalived/keepalived.conf
    #master
    global_defs { 
      router_id 172.18.62.38
    }
    
    vrrp_script check_nginx { 
        script "/etc/keepalived/check_nginx.sh"
        interval 2
        weight 2
    }
    
    vrrp_instance vrrptest { 
           state master
           interface eth0
           virtual_router_id 51
           priority 150
           advert_int 1
           authentication { 
               auth_type PASS
               auth_pass ufsoft
           }
           track_script { 
               check_nginx
           }
           virtual_ipaddress { 
               172.18.62.43
           }
    }
    #backup
    global_defs { 
      router_id 172.18.62.39
    }
    
    vrrp_script check_nginx { 
        script "/etc/keepalived/check_nginx.sh"
        interval 2
        weight 2
    }
    
    vrrp_instance vrrptest { 
           state master
           interface eth0
           virtual_router_id 51
           priority 150
           advert_int 1
           authentication { 
               auth_type PASS
               auth_pass ufsoft
           }
           track_script { 
               check_nginx
           }
           virtual_ipaddress { 
               172.18.62.43
           }
    }
    #启动keepalived
    /etc/init.d/keeplived start

`8、检查nginx脚本`

if [ "$(ps -ef | grep "nginx:master process"| grep -v grep )" == "" ];then
      /etc/init.d/keepalived stop
    else
      echo "nginx is running"
    fi

`9、测试`

#master
    http://Ip:80

![在这里插入图片描述][20210506153634867.png]  
![在这里插入图片描述][20210506153709887.png]

#backup
    http://IP:90

![在这里插入图片描述][20210506153907841.png]  
![在这里插入图片描述][20210506153923518.png]

#VIP
    http://IP:100

![在这里插入图片描述][20210506154200865.png]  
![在这里插入图片描述][20210506154218806.png]  
`10、故障测试`

#停掉master
    root@nginx-master:/etc/keepalived# /etc/init.d/keepalived stop
    Stopping keepalived (via systemctl): keepalived.service.

http://IP:100依旧正常访问

![在这里插入图片描述][20210506154541935.png]  
![在这里插入图片描述][20210506154605541.png]

[20210506153634867.png]: /images/20221021/595c308cc7224853bd91c6842389fd2b.png
[20210506153709887.png]: /images/20221021/c98a5d9134654794a281017801572211.png
[20210506153907841.png]: /images/20221021/06faeb273eec41c2ae4a3295c50d4134.png
[20210506153923518.png]: /images/20221021/20e56f7d34754f17981bbd97599907dc.png
[20210506154200865.png]: /images/20221021/ab38419fc0bc4c3a980560c1fa8c35fb.png
[20210506154218806.png]: /images/20221021/32c7d626918e4189b9aaf33c8a14e00a.png
[20210506154541935.png]: /images/20221021/ad5e5915d62a49fa83c496aabad9ad39.png
[20210506154605541.png]: /images/20221021/c238b77f039f459a8a8071c04d10517f.png