用LVS实现负载均衡

实现步骤：

    #若在虚拟环境中需执行此步骤创建两个新的虚拟机，VMWARE可忽略此步骤
     
   真实主机:
              cd /var/lib/libvirt/images/
          ls
          qemu-img create -f qcow2 -b rhel7.6.qcow2 server3
          qemu-img create -f qcow2 -b rhel7.6.qcow2 server4


server1:
      pcs cluster disable --all
      pcs cluster stop --all
      systemctl status pcsd
      systemctl disable --now pcsd
      ssh server2 disable --now pcsd
      ssh server2 systemctl disable --now pcsd

  server3:
          hostnamectl set-hostname server3
          cd /etc/yum.repos.d/
          vim dvd.repo
          yum install httpd
          systemctl enable --now httpd
          systemctl start httpd
          cd /var/www/html/
          echo vm3> index.html
          ip addr add 172.25.19.100/24 dev eth0
          yum install -y arptables
          arptables -A INPUT -d 172.25.19.100 -j DROP
          arptables -A OUTPUT -s 172.25.19.100 -j mangle --mangle-ip-s 172.25.19.3

   server4:
          hostnamectl set-hostname server4
          cd /etc/yum.repos.d/
          vim dvd.repo
          yum install httpd
          systemctl enable --now httpd
          systemctl start httpd
          cd /var/www/html/
          echo vm3> index.html
          ip addr add 172.25.19.100/24 dev eth0
          yum install -y arptables
          arptables -A INPUT -d 172.25.19.100 -j DROP
          arptables -A OUTPUT -s 172.25.19.100 -j mangle --mangle-ip-s 172.25.19.4

 server2:
        curl server3
        curl server4
        yum install ipvsadm -y
        ip addr add 172.25.19.100/24 dev eth0
        ipvsadm -A -t 172.25.19.100:80 -s rr
        ipvsadm -a -t 172.25.19.100:80 -r 172.25.19.3:80 -g
        ipvsadm -a -t 172.25.19.100:80 -r 172.25.19.4:80 -g
        ipvsadm -ln

    真实主机:
          curl 172.25.19.100

负载均衡（轮询机制）实现

LVS+keepalived实现负载均衡健康监测

实验目的

上个实验中实现了负载均衡。本实验中我们将结合keepalived实现负载均衡高级群的健康监测，即在一真实主机的apache关闭后，主机可以监测到，并不再访问这台关闭apache的主机。

实验环境

五台虚拟机：home为主机，server1、server2为VS调度，server3、server4为RS真实主机。

实验步骤

1.环境搭建

server1、server2：   


  ipvsadm -C            清除IPVS中的IP，因为IPVS的配置会与keepalived冲突
   ipvsadm -ln
   yum install keepalived -y
   ip addr del 172.25.19.100/24 dev eth0
   vim /etc/keepalived/keepalived.conf   编写此文件相当于用配置文件的方式实现负载均衡
        server1 keepalived.conf:


 ! Configuration File for keepalived    
global_defs {
    notification_email {
      root@localhost
    }
    notification_email_from keepalived@localhost
    smtp_server 127.0.0.1
    smtp_connect_timeout 30
    router_id LVS_DEVEL
    vrrp_skip_check_adv_addr
    #vrrp_strict
    vrrp_garp_interval 0
    vrrp_gna_interval 0
 }
  
vrrp_instance VI_1 {
     state MASTER
     interface eth0
     virtual_router_id 51
     priority 100
     advert_int 1
     authentication {
         auth_type PASS
         auth_pass 1111
     }
     virtual_ipaddress {
         172.25.19.100
     }
 }
  
virtual_server 172.25.19.100 80 {
     delay_loop 6
     lb_algo rr
     lb_kind DR
     #persistence_timeout 50
     protocol TCP
        real_server 172.25.19.3 80 {
         weight 1
         TCP_CHECK {
             connect_timeout 3
             nb_get_retry 3
             delay_before_retry 3
         }
     }
        real_server 172.25.19.4 80 {
         weight 1
         TCP_CHECK {
             connect_timeout 3
             nb_get_retry 3
             delay_before_retry 3
         }
     }
 }


   server2 keepalived.conf:
    ! Configuration File for keepalived
         global_defs {
       notification_email {
         root@localhost
       }
       notification_email_from keepalived@localhost
       smtp_server 127.0.0.1
       smtp_connect_timeout 30
       router_id LVS_DEVEL
       vrrp_skip_check_adv_addr
       #vrrp_strict
       vrrp_garp_interval 0
       vrrp_gna_interval 0
    }
     
   vrrp_instance VI_1 {
        state BACKUP
        interface eth0
        virtual_router_id 51
        priority 50
        advert_int 1
        authentication {
            auth_type PASS
            auth_pass 1111
        }
        virtual_ipaddress {
            172.25.19.100
        }
    }
         virtual_server 172.25.19.100 80 {
        delay_loop 6
        lb_algo rr
        lb_kind DR
        #persistence_timeout 50
        protocol TCP
     
   real_server 172.25.19.3 80 {
            weight 1
            TCP_CHECK {
                connect_timeout 3
                nb_get_retry 3
                delay_before_retry 3
            }
        }
            real_server 172.25.19.4 80 {
            weight 1
            TCP_CHECK {
                connect_timeout 3
                nb_get_retry 3
                delay_before_retry 3
            }
        }
    }


 systemctl restart keepalived.service 
 tail -f /var/log/messages    
 ipvsadm -ln      执行此命令后发现ip已配置完毕

2.健康检测

1）RS真实主机健康检测

在server3中 关闭httpd服务
 
systemctl stop httpd

此时在真实主机中执行

curl 172.25.19.100

发现主机已知晓3的服务关闭，并且主机策略已不存在server3

并发送邮件给了server1、server2

再开启server3中的httpd，并在主机中检测，发现已恢复正常

2）DS健康检测

关闭server1中的keepalived服务
 
[root@server1 ~]# systemctl stop keepalived.service 

此时在server2中：
 
tail -f /var/log/messages
 
发现server2已接管server1

在主机中探测RS发现不收任何影响，即keepalived解决了DS的单点故障