keepalived高可用

keepalived高可用

目录

• keepalived高可用
  • keepalived简介
  • keepalived的重要功能
  • keepalived高可用故障转移的原理
  • keepalived配置文件
    • 定制主配置文件
• keepalived实现nginx高可用
  • • 准备工作
    • 安装并配置nginx
    • 安装并配置keepalived
    • 访问测试
  • 配置脚本
    • master编写脚本
    • backup编写脚本
    • 配置keepalived加入监控脚本的配置
    • 实验
• keepalived实现haproxy负载均衡高可用
  • • 准备工作
    • 部署haproxy负载均衡
    • 部署keepalived高可用
  • 编写脚本
    • 配置keepalived加入监控脚本的配置
    • 测试

keepalived简介

Keepalived 软件起初是专为LVS负载均衡软件设计的，用来管理并监控LVS集群系统中各个服务节点的状态，后来又加入了可以实现高可用的VRRP功能。因此，Keepalived除了能够管理LVS软件外，还可以作为其他服务（例如：Nginx、Haproxy、MySQL等）的高可用解决方案软件。

Keepalived软件主要是通过VRRP协议实现高可用功能的。VRRP是Virtual Router RedundancyProtocol(虚拟路由器冗余协议）的缩写，VRRP出现的目的就是为了解决静态路由单点故障问题的，它能够保证当个别节点宕机时，整个网络可以不间断地运行。

所以，Keepalived 一方面具有配置管理LVS的功能，同时还具有对LVS下面节点进行健康检查的功能，另一方面也可实现系统网络服务的高可用功能。
keepalived官网

keepalived的重要功能

keepalived 有三个重要的功能，分别是：

管理LVS负载均衡软件
实现LVS集群节点的健康检查
keepalived 有三个重要的功能，分别是：
管理LVS负载均衡软件
实现LVS集群节点的健康检查
作为系统网络服务的高可用性（failover）作为系统keepalived 有三个重要的功能，分别是：

管理LVS负载均衡软件
实现LVS集群节点的健康检查
作为系统网络服务的高可用性（failover）网络服务的高可用性（failover）

keepalived高可用故障转移的原理

Keepalived 高可用服务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。

什么是VRRP
VRRP ,全 称 Virtual Router Redundancy Protocol ,中文名为虚拟路由冗余协议 ，VRRP的出现就是为了解决静态踣甶的单点故障问题，VRRP是通过一种竞选机制来将路由的任务交给某台VRRP路由器的。

keepalived配置文件

keepalived 的主配置文件是 /etc/keepalived/keepalived.conf。其内容如下：

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

global_defs {       //全局配置
   notification_email {     //定义报警收件人邮件地址
     acassen@firewall.loc
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from Alexandre.Cassen@firewall.loc    //定义报警发件人邮箱
   smtp_server 192.168.118.1    //邮箱服务器地址
   smtp_connect_timeout 30      //定义邮箱超时时间
   router_id LVS_DEVEL          //定义路由标识信息，同局域网内唯一
   vrrp_skip_check_adv_addr
   vrrp_strict
   vrrp_garp_interval 0
   vrrp_gna_interval 0
}

vrrp_instance VI_1 {        //定义实例
    state MASTER            //指定keepalived节点的初始状态，可选值为MASTER|BACKUP
    interface eth0          //VRRP实例绑定的网卡接口，用户发送VRRP包
    virtual_router_id 51    //虚拟路由的ID，同一集群要一致
    priority 100            //定义优先级，按优先级来决定主备角色，优先级越大越优先
    nopreempt               //设置不抢占
    advert_int 1            //主备通讯时间间隔
    authentication {        //配置认证
        auth_type PASS      //认证方式，此处为密码
        auth_pass 1111      //同一集群中的keepalived配置里的此处必须一致，推荐使用8位随机数
    }
    virtual_ipaddress {     //配置要使用的VIP地址
        192.168.118.16
    }
}

virtual_server 192.168.118.16 1358 {    //配置虚拟服务器
    delay_loop 6        //健康检查的时间间隔
    lb_algo rr          //lvs调度算法
    lb_kind NAT         //lvs模式
    persistence_timeout 50      //持久化超时时间，单位是秒
    protocol TCP        //4层协议

    sorry_server 192.168.118.200 1358   //定义备用服务器，当所有RS都故障时用sorry_server来响应客户端

    real_server 192.168.118.2 1358 {    //定义真实处理请求的服务器
        weight 1    //给服务器指定权重，默认为1
        HTTP_GET {
            url {
              path /testurl/test.jsp    //指定要检查的URL路径
              digest 640205b7b0fc66c1ea91c463fac6334d   //摘要信息
            }
            url {
              path /testurl2/test.jsp
              digest 640205b7b0fc66c1ea91c463fac6334d
            }
            url {
              path /testurl3/test.jsp
              digest 640205b7b0fc66c1ea91c463fac6334d
            }
            connect_timeout 3       //连接超时时间
            nb_get_retry 3          //get尝试次数
            delay_before_retry 3    //在尝试之前延迟多长时间
        }
    }

    real_server 192.168.118.3 1358 {
        weight 1
        HTTP_GET {
            url {
              path /testurl/test.jsp
              digest 640205b7b0fc66c1ea91c463fac6334c
            }
            url {
              path /testurl2/test.jsp
              digest 640205b7b0fc66c1ea91c463fac6334c
            }
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}

定制主配置文件

vrrp_instance段配置

nopreempt   //设置为不抢占。默认是抢占的，当高优先级的机器恢复后，会抢占低优先 \
级的机器成为MASTER，而不抢占，则允许低优先级的机器继续成为MASTER，即使高优先级 \
的机器已经上线。如果要使用这个功能，则初始化状态必须为BACKUP。

preempt_delay   //设置抢占延迟。单位是秒，范围是0---1000，默认是0.发现低优先 \
级的MASTER后多少秒开始抢占。

vrrp_script段配置

//作用：添加一个周期性执行的脚本。脚本的退出状态码会被调用它的所有的VRRP Instance记录。
//注意：至少有一个VRRP实例调用它并且优先级不能为0.优先级范围是1-254.
vrrp_script <SCRIPT_NAME> {
          ...
    }

//选项说明：
script "/path/to/somewhere"      //指定要执行的脚本的路径。
interval <INTEGER>              //指定脚本执行的间隔。单位是秒。默认为1s。
timeout <INTEGER>               //指定在多少秒后，脚本被认为执行失败。
weight <-254 --- 254>           //调整优先级。默认为2.
rise <INTEGER>                  //执行成功多少次才认为是成功。
fall <INTEGER>                  //执行失败多少次才认为失败。
user <USERNAME> [GROUPNAME]     //运行脚本的用户和组。
init_fail                       //假设脚本初始状态是失败状态。

//weight说明： 
1. 如果脚本执行成功(退出状态码为0)，weight大于0，则priority增加。
2. 如果脚本执行失败(退出状态码为非0)，weight小于0，则priority减少。
3. 其他情况下，priority不变。

real_server段配置

weight <INT>            //给服务器指定权重。默认是1
inhibit_on_failure      //当服务器健康检查失败时，将其weight设置为0， \
                        //而不是从Virtual Server中移除
notify_up <STRING>      //当服务器健康检查成功时，执行的脚本
notify_down <STRING>    //当服务器健康检查失败时，执行的脚本
uthreshold <INT>        //到这台服务器的最大连接数
lthreshold <INT>        //到这台服务器的最小连接数

tcp_check段配置

connect_ip <IP ADDRESS>     //连接的IP地址。默认是real server的ip地址
connect_port <PORT>         //连接的端口。默认是real server的端口
bindto <IP ADDRESS>         //发起连接的接口的地址。
bind_port <PORT>            //发起连接的源端口。
connect_timeout <INT>       //连接超时时间。默认是5s。
fwmark <INTEGER>            //使用fwmark对所有出去的检查数据包进行标记。
warmup <INT>    //指定一个随机延迟，最大为N秒。可防止网络阻塞。如果为0，则关闭该功能。
retry <INIT>                //重试次数。默认是1次。
delay_before_retry <INT>    //默认是1秒。在重试之前延迟多少秒。

keepalived实现nginx高可用

环境介绍

主机名	ip
master	192.168.118.129
backup	192.168.118.128

准备工作

master

#修改master主机名
[root@localhost ~]# hostnamectl set-hostname master
[root@localhost ~]# bash

#关闭防火墙和selinux
[root@master ~]# systemctl disable --now firewalld.service
Removed /etc/systemd/system/multi-user.target.wants/firewalld.service.
Removed /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service.
[root@master ~]# setenforce 0
[root@master ~]# sed -ri 's/^(SELINUX=).*/\1disabled/g' /etc/selinux/config
[root@backup ~]# reboot

backup

#修改backup主机名
[root@localhost ~]# hostnamectl set-hostname backup
[root@localhost ~]# bash

#关闭防火墙和selinux
[root@backup ~]# systemctl disable --now firewalld.service 
Removed /etc/systemd/system/multi-user.target.wants/firewalld.service.
Removed /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service.
[root@backup ~]# setenforce 0
[root@backup ~]# sed -ri 's/^(SELINUX=).*/\1disabled/g' /etc/selinux/config
[root@backup ~]# reboot

安装并配置nginx

master配置nginx

[root@master ~]# yum -y install nginx

[root@master ~]# cd /usr/share/nginx/html/
[root@master html]# mv index.html{,.bak}
[root@master html]# echo 'master' > index.html  //备份配置原配置文件
[root@master html]# cat index.html
master

[root@master ~]# systemctl start nginx.service  //开启nginx

[root@master ~]# curl 192.168.118.129
master

backup配置nginx

[root@backup ~]# yum -y install nginx

[root@backup ~]# cd /usr/share/nginx/html/
[root@backup html]# mv index.html{,.bak}
[root@backup html]# echo 'backup' > index.html
[root@backup html]# cat index.html
backup

[root@backup]# systemctl start nginx.service    

[root@backup]# curl 192.168.118.128
backup

安装并配置keepalived

master安装配置keepalived

[root@master ~]# yum -y install keepalived

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

global_defs {
    router_id lb01
}

vrrp_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.118.250
    }
}

virtual_server 192.168.118.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind NAT
    persistence_timeout 50
    protocol TCP

    real_server 192.168.118.129 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }

    real_server 192.168.118.128 80 {
        weight 1keepa
        TCP_CHECK {
            connect_port 80 
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}

#启动keepalived
[root@master ~]# systemctl start keepalived.service
[root@master ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:0c:29:b5:9a:13 brd ff:ff:ff:ff:ff:ff
    inet 192.168.118.129/24 brd 192.168.118.255 scope global dynamic noprefixroute ens33
       valid_lft 1121sec preferred_lft 1121sec
    inet 192.168.118.250/32 scope global ens33       //当keepalived启动后 会生成vip
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:feb5:9a13/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

backup安装配置keepalived

[root@backup ~]# yum -y install keepalived

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

global_defs {
    router_id lb02
}

vrrp_instance VI_1 {
    state BACKUP          //修改为backup
    interface ens33
    virtual_router_id 51
    priority 90          //修改优先级 因为是备 所以优先级更低
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.118.250
    }
}

virtual_server 192.168.118.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind NAT
    persistence_timeout 50
    protocol TCP

    real_server 192.168.118.129 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }

    real_server 192.168.118.128 80 {
        weight 1keepa
        TCP_CHECK {
            connect_port 80 
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}

[root@backup ~]# systemctl start keepalived.service
[root@backup ~]# ip a      //因为优先级低 所以没有vip
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:0c:29:16:02:99 brd ff:ff:ff:ff:ff:ff
    inet 192.168.118.128/24 brd 192.168.118.255 scope global dynamic noprefixroute ens33
       valid_lft 1140sec preferred_lft 1140sec
    inet6 fe80::20c:29ff:fe16:299/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

访问测试

master在浏览器上使用vip进行访问

正常情况下主(master)的keepalived和nginx都是开启的,备(backup)的nginx是关闭的

[root@backup ~]# systemctl stop nginx

backup在浏览器上使用vip进行访问

关闭master主机的keepalived服务

[root@master ~]# systemctl stop keepalived.service

这时backup主机生成了vip

[root@backup ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:0c:29:16:02:99 brd ff:ff:ff:ff:ff:ff
    inet 192.168.118.128/24 brd 192.168.118.255 scope global dynamic noprefixroute ens33
       valid_lft 1735sec preferred_lft 1735sec
    inet 192.168.118.250/32 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe16:299/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
[root@backup ~]# systemctl start nginx      //开启nginx

在浏览器中访问

配置脚本

恢复环境

正常情况下主(master)的keepalived和nginx都是开启的,备(backup)的nginx是关闭的

[root@master ~]# systemctl start keepalived.service  //启动master的keepalived服务

[root@backup ~]# systemctl stop nginx  //关闭backup的nginx服务

master编写脚本

此脚本用于控制keepalived是否关闭，当master的nginx异常，而关闭时就自动关闭keepalived服务以便让backup能获得vip

[root@master ~]# mkdir /scripts
[root@master ~]# cd /scripts/
[root@master scripts]# touch check_m.sh
[root@master scripts]# vim check_m.sh 
#!/bin/bash
nginx_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bnginx\b'|wc -l)
if [ $nginx_status -lt 1 ];then
       systemctl stop keepalived
fi

[root@master scripts]# chmod +x check_m.sh
[root@master scripts]# ll
total 4
-rwxr-xr-x 1 root root 145 Oct  9 00:29 check_m.sh

此脚本用于检查主机是否为master和backup 来控制nginx是否关闭和开启

[root@master scripts]# touch notify.sh
[root@master scripts]# vim notify.sh
[root@backup scripts]# cat notify.sh
#!/bin/bash
VIP=$2
#sendmail (){          //注释内容为异常时发送邮件，实验并不需要
#       subject="${VIP}'s server keepalived state is translate"
#       content="`date +'%F %T'`: `hostname`'s state change to master"
#       echo $content | mail -s "$subject" **********@qq.com
#}
case "$1" in
master)
        nginx_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bnginx\b'|wc -l)
        if [ $nginx_status -lt 1 ];then
                systemctl start nginx
        fi
        sendmail
;;
backup)
        nginx_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bnginx\b'|wc -l)
        if [ $nginx_status -gt 0 ];then
                systemctl stop nginx
        fi
;;
*)
        echo "Usage:$0 master|backup VIP"
;;
esac

[root@master scripts]# chmod +x notify.sh
[root@master scripts]# ll
total 8
-rwxr-xr-x 1 root root 145 Oct  9 00:29 check_m.sh
-rwxr-xr-x 1 root root 572 Oct  9 00:36 notify.sh

backup编写脚本

[root@backup ~]# mkdir /scripts
[root@backup ~]# cd /scripts/
[root@backup scripts]# touch notify.sh
[root@backup scripts]# vim notify.sh 
[root@backup scripts]# cat notify.sh 
#!/bin/bash
VIP=$2
#sendmail (){
#       subject="${VIP}'s server keepalived state is translate"
#       content="`date +'%F %T'`: `hostname`'s state change to master"
#       echo $content | mail -s "$subject" **********@qq.com
#}
case "$1" in
master)
        nginx_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bnginx\b'|wc -l)
        if [ $nginx_status -lt 1 ];then
                systemctl start nginx
        fi
        sendmail
;;
backup)
        nginx_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bnginx\b'|wc -l)
        if [ $nginx_status -gt 0 ];then
                systemctl stop nginx
        fi
;;
*)
        echo "Usage:$0 master|backup VIP"
;;
esac
[root@backup scripts]# chmod +x notify.sh 
[root@backup scripts]# ll
total 4
-rwxr-xr-x 1 root root 558 Oct  9 00:41 notify.sh

配置keepalived加入监控脚本的配置

主(master)配置keepalived

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

global_defs {
    router_id lb01
}

vrrp_script nginx_check {        //添加此处
    script "/scripts/check_m.sh"
    interval 1
    weight -20
}

vrrp_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.118.250
    }
    track_script {           //添加此处
        nginx_check
    }
    notify_master "/scripts/notify.sh master 192.168.118.250"
}

virtual_server 192.168.118.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind NAT
    persistence_timeout 50
    protocol TCP

    real_server 192.168.118.129 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }

    real_server 192.168.118.128 80 {
        weight 1keepa
        TCP_CHECK {
            connect_port 80 
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}

[root@master ~]# systemctl restart keepalived.service //重启服务

备用(backup)配置keepalived

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

global_defs {
    router_id lb02
}

vrrp_instance VI_1 {
    state BACKUP
    interface ens33
    virtual_router_id 51
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.118.250
    }
    notify_master "/scripts/notify.sh master 192.168.118.250"
    notify_backup "/scripts/notify.sh backup 192.168.118.250"
}
virtual_server 192.168.118.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind NAT
    persistence_timeout 50
    protocol TCP

    real_server 192.168.118.129 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }

    real_server 192.168.118.128 80 {
        weight 1
        TCP_CHECK {
            connect_port 80 
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}

[root@backup ~]# systemctl restart keepalived.service //重启服务

实验

这时保证master主机nginx与keepalived服务都处于开启状态，backup主机nginx处于关闭keepalived处于开启状态

关闭master的nginx服务

[root@master ~]# systemctl stop nginx
[root@master ~]# ip a     //vip消失了
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:0c:29:b5:9a:13 brd ff:ff:ff:ff:ff:ff
    inet 192.168.118.129/24 brd 192.168.118.255 scope global dynamic noprefixroute ens33
       valid_lft 1294sec preferred_lft 1294sec
    inet6 fe80::20c:29ff:feb5:9a13/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

当master的nginx服务异常时，backup抢占vip开启nginx服务

[root@backup ~]# systemctl status nginx
● nginx.service - The nginx HTTP and reverse proxy server
   Loaded: loaded (/usr/lib/systemd/system/nginx.service; disabled; vendor pres>
   Active: active (running) since Sun 2022-10-09 00:56:16 CST; 3min 42s ago
  Process: 143804 ExecStart=/usr/sbin/nginx (code=exited, status=0/SUCCESS)
  Process: 143802 ExecStartPre=/usr/sbin/nginx -t (code=exited, status=0/SUCCES>
  Process: 143799 ExecStartPre=/usr/bin/rm -f /run/nginx.pid (code=exited, stat>
...省略

[root@backup ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:0c:29:16:02:99 brd ff:ff:ff:ff:ff:ff
    inet 192.168.118.128/24 brd 192.168.118.255 scope global dynamic noprefixroute ens33
       valid_lft 1070sec preferred_lft 1070sec
    inet 192.168.118.250/32 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe16:299/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

浏览器这时应访问backup

正常情况下主的nginx和keepalived服务是开启的，备的nginx是关闭keeplived服务是开启的。当主的nginx服务异常时通过监控或者脚本用邮件发送告警信息给用户，当需要恢复主的服务时需要手动将主的nginx异常修复后并将nginx和keepalived服务重启，主就拥有了vip并可以正常访问到master

开启master的nginx服务和keepalived服务

[root@master ~]# systemctl start nginx
[root@master ~]# systemctl restart keepalived.service


[root@master ~]# ip a   //重新获取到了vip
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:0c:29:b5:9a:13 brd ff:ff:ff:ff:ff:ff
    inet 192.168.118.129/24 brd 192.168.118.255 scope global dynamic noprefixroute ens33
       valid_lft 1777sec preferred_lft 1777sec
    inet 192.168.118.250/32 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:feb5:9a13/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

浏览器这时应访问到master

keepalived实现haproxy负载均衡高可用

环境介绍

主机名	ip	服务
master	192.168.118.129	haproxy keepalived
backup	192.168.118.128	haproxy keepalived
RS1	192.168.118.130	nginx
RS2	192.168.118.131	httpd

准备工作

master

#修改master主机名
[root@localhost ~]# hostnamectl set-hostname master
[root@localhost ~]# bash

#关闭防火墙和selinux
[root@master ~]# systemctl disable --now firewalld.service
Removed /etc/systemd/system/multi-user.target.wants/firewalld.service.
Removed /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service.
[root@master ~]# setenforce 0
[root@master ~]# sed -ri 's/^(SELINUX=).*/\1disabled/g' /etc/selinux/config
[root@backup ~]# reboot

backup

#修改backup主机名
[root@localhost ~]# hostnamectl set-hostname backup
[root@localhost ~]# bash

#关闭防火墙和selinux
[root@backup ~]# systemctl disable --now firewalld.service 
Removed /etc/systemd/system/multi-user.target.wants/firewalld.service.
Removed /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service.
[root@backup ~]# setenforce 0
[root@backup ~]# sed -ri 's/^(SELINUX=).*/\1disabled/g' /etc/selinux/config
[root@backup ~]# reboot

RS1

#修改RS1主机名
[root@localhost ~]# hostnamectl set-hostname RS1
[root@localhost ~]# bash

#关闭防火墙和selinux
[root@RS1 ~]# systemctl disable --now firewalld.service
Removed /etc/systemd/system/multi-user.target.wants/firewalld.service.
Removed /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service.
[root@RS1 ~]# setenforce 0
[root@RS1 ~]# sed -ri 's/^(SELINUX=).*/\1disabled/g' /etc/selinux/config
[root@RS1 ~]# reboot

#安装nginx服务，主页内容为web1
[root@RS1 ~]# dnf -y install nginx
[root@RS1 ~]# echo "web1" > /usr/share/nginx/html/index.html
[root@RS1 ~]# systemctl enable --now nginx.service
Created symlink /etc/systemd/system/multi-user.target.wants/nginx.service → /usr/lib/systemd/system/nginx.service.
[root@RS1 ~]# ss -antl
State    Recv-Q   Send-Q     Local Address:Port     Peer Address:Port  Process  
LISTEN   0        128              0.0.0.0:80            0.0.0.0:*              
LISTEN   0        128              0.0.0.0:22            0.0.0.0:*              
LISTEN   0        128                 [::]:80               [::]:*              
LISTEN   0        128                 [::]:22               [::]:*              
[root@RS1 ~]# curl 192.168.118.130
web1

RS2

#修改RS2主机名
[root@localhost ~]# hostnamectl set-hostname RS2
[root@localhost ~]# bash

#关闭防火墙和selinux
[root@RS2 ~]# systemctl disable --now firewalld.service
Removed /etc/systemd/system/multi-user.target.wants/firewalld.service.
Removed /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service.
[root@RS2 ~]# setenforce 0
[root@RS2 ~]# sed -ri 's/^(SELINUX=).*/\1disabled/g' /etc/selinux/config
[root@RS2 ~]# reboot

#安装httpd服务，主页内容为web2
[root@RS2 ~]# dnf -y install httpd
[root@RS2 ~]# echo "web2" > /var/www/html/index.html
[root@RS2 ~]# systemctl enable --now httpd.service
Created symlink /etc/systemd/system/multi-user.target.wants/httpd.service → /usr/lib/systemd/system/httpd.service.
[root@RS2 ~]# ss -antl
State    Recv-Q   Send-Q     Local Address:Port     Peer Address:Port  Process  
LISTEN   0        128              0.0.0.0:22            0.0.0.0:*              
LISTEN   0        128                    *:80                  *:*              
LISTEN   0        128                 [::]:22               [::]:*              
[root@RS2 ~]# curl 192.168.118.131
web2

部署haproxy负载均衡

master

#创建用户
[root@master ~]# useradd -rMs /sbin/nologin haproxy
 
#下载依赖包
[root@master ~]# dnf -y install make gcc pcre-devel bzip2-devel openssl-devel systemd-devel wget vim
 
#下载haproxy压缩包
[root@master ~]# wget https://src.fedoraproject.org/repo/pkgs/haproxy/haproxy-2.6.0.tar.gz/sha512/7bb70bfb5606bbdac61d712bc510c5e8d5a5126ed8827d699b14a2f4562b3bd57f8f21344d955041cee0812c661350cca8082078afe2f277ff1399e461ddb7bb/haproxy-2.6.0.tar.gz
 
#解压并安装
[root@master ~]# tar -xf haproxy-2.6.0.tar.gz
[root@master ~]# cd haproxy-2.6.0
[root@master haproxy-2.6.0]# make -j $(grep 'processor' /proc/cpuinfo |wc -l)  \
TARGET=linux-glibc  \
USE_OPENSSL=1  \
USE_ZLIB=1  \
USE_PCRE=1  \
USE_SYSTEMD=1
 
[root@master haproxy-2.6.0]# make install PREFIX=/usr/local/haproxy
 
#复制命令到/usr/sbin目录下
[root@master haproxy-2.6.0]# cp haproxy /usr/sbin/
[root@master haproxy-2.6.0]# cd
 
#修改内核参数
[root@master ~]# vim /etc/sysctl.conf
...省略
net.ipv4.ip_nonlocal_bind = 1
net.ipv4.ip_forward = 1
 
[root@master ~]# sysctl -p
net.ipv4.ip_nonlocal_bind = 1
net.ipv4.ip_forward = 1
 
#修改配置文件
[root@master ~]# mkdir /etc/haproxy
[root@master ~]# vim /etc/haproxy/haproxy.cfg
global
    daemon
    maxconn 256
 
defaults
    mode http
    timeout connect 5000ms
    timeout client 50000ms
    timeout server 50000ms
 
frontend http-in
    bind *:80
    default_backend servers
 
backend servers
    server web01 192.168.118.130:80
    server web02 192.168.118.131:80
 
#编写service文件，并启动服务
[root@master ~]# vim /usr/lib/systemd/system/haproxy.service
[Unit]
Description=HAProxy Load Balancer
After=syslog.target network.target
 
[Service]
ExecStartPre=/usr/local/haproxy/sbin/haproxy -f /etc/haproxy/haproxy.cfg   -c -q
ExecStart=/usr/local/haproxy/sbin/haproxy -Ws -f /etc/haproxy/haproxy.cfg  -p /var/run/haproxy.pid
ExecReload=/bin/kill -USR2 $MAINPID
 
[Install]
WantedBy=multi-user.target

[root@master ~]# systemctl daemon-reload
[root@master ~]# systemctl start haproxy.service 
[root@master ~]# ss -antl
State    Recv-Q   Send-Q     Local Address:Port     Peer Address:Port  Process  
LISTEN   0        128              0.0.0.0:80            0.0.0.0:*              
LISTEN   0        128              0.0.0.0:22            0.0.0.0:*              
LISTEN   0        128                 [::]:22               [::]:*   
#查看负载均衡效果
[root@master ~]# curl 192.168.118.129
web1
[root@master ~]# curl 192.168.118.129
web2
[root@master ~]# curl 192.168.118.129
web1
[root@master ~]# curl 192.168.118.129
web2

backup

[root@backup ~]# dnf -y install nginx 
 
#创建用户
[root@backup ~]# useradd -rMs /sbin/nologin haproxy
 
#下载依赖包
[root@backup ~]# dnf -y install make gcc pcre-devel bzip2-devel openssl-devel systemd-devel wget vim
 
#下载haproxy压缩包
[root@backup ~]# wget https://src.fedoraproject.org/repo/pkgs/haproxy/haproxy-2.6.0.tar.gz/sha512/7bb70bfb5606bbdac61d712bc510c5e8d5a5126ed8827d699b14a2f4562b3bd57f8f21344d955041cee0812c661350cca8082078afe2f277ff1399e461ddb7bb/haproxy-2.6.0.tar.gz
 
#解压并安装
[root@backup ~]# tar -xf haproxy-2.6.0.tar.gz
[root@backup ~]# cd haproxy-2.6.0
[root@backup haproxy-2.6.0]# make -j $(grep 'processor' /proc/cpuinfo |wc -l)  \
TARGET=linux-glibc  \
USE_OPENSSL=1  \
USE_ZLIB=1  \
USE_PCRE=1  \
USE_SYSTEMD=1

[root@backup haproxy-2.6.0]# make install PREFIX=/usr/local/haproxy

#复制命令到/usr/sbin目录下
[root@backup haproxy-2.6.0]# cp haproxy /usr/sbin/
[root@backup haproxy-2.6.0]# cd
 
#修改内核参数
[root@backup ~]# vim /etc/sysctl.conf
...省略
net.ipv4.ip_nonlocal_bind = 1
net.ipv4.ip_forward = 1
 
[root@backup ~]# sysctl -p
net.ipv4.ip_nonlocal_bind = 1
net.ipv4.ip_forward = 1
 
#修改配置文件
[root@backup ~]# mkdir /etc/haproxy
[root@backup ~]# vim /etc/haproxy/haproxy.cfg
global
    daemon
    maxconn 256
 
defaults
    mode http
    timeout connect 5000ms
    timeout client 50000ms
    timeout server 50000ms
 
frontend http-in
    bind *:80
    default_backend servers
 
backend servers
    server web01 192.168.118.130:80
    server web02 192.168.118.131:80
    
#编写service文件，并启动服务
[root@backup ~]# vim /usr/lib/systemd/system/haproxy.service
[Unit]
Description=HAProxy Load Balancer
After=syslog.target network.target
 
[Service]
ExecStartPre=/usr/local/haproxy/sbin/haproxy -f /etc/haproxy/haproxy.cfg   -c -q
ExecStart=/usr/local/haproxy/sbin/haproxy -Ws -f /etc/haproxy/haproxy.cfg  -p /var/run/haproxy.pid
ExecReload=/bin/kill -USR2 $MAINPID
 
[Install]
WantedBy=multi-user.target
 
[root@backup ~]# systemctl daemon-reload 
[root@backup ~]# systemctl start haproxy.service 
[root@backup ~]# ss -antl
State    Recv-Q   Send-Q     Local Address:Port     Peer Address:Port  Process  
LISTEN   0        128              0.0.0.0:80            0.0.0.0:*              
LISTEN   0        128              0.0.0.0:22            0.0.0.0:*              
LISTEN   0        128                 [::]:22               [::]:* 

#查看负载均衡效果
[root@backup ~]# curl 192.168.118.128
web1
[root@backup ~]# curl 192.168.118.128
web2
[root@backup ~]# curl 192.168.118.128
web1
[root@backup ~]# curl 192.168.118.128
web2
 
#backup端的负载均衡器最好关掉
[root@backup ~]# systemctl stop haproxy.service

部署keepalived高可用

master

#首先安装keepalived
[root@master ~]# dnf -y install keepalived
 
#编辑配置文件
[root@master ~]# vim /etc/keepalived/keepalived.conf
[root@master ~]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived

global_defs {
   router_id lb01
}

vrrp_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.118.250
    } 
}
virtual_server 192.168.118.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP

    real_server 192.168.118.129 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }

    real_server 192.168.118.128 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}

#并启动服务
[root@master ~]# systemctl start keepalived.service
 
#通过虚拟ip访问
[root@master ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:0c:29:b5:9a:13 brd ff:ff:ff:ff:ff:ff
    inet 192.168.118.129/24 brd 192.168.118.255 scope global dynamic noprefixroute ens33
       valid_lft 1066sec preferred_lft 1066sec
    inet 192.168.118.250/32 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:feb5:9a13/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

[root@master ~]# curl 192.168.118.250
web1
[root@master ~]# curl 192.168.118.250
web2
[root@master ~]# curl 192.168.118.250
web1
[root@master ~]# curl 192.168.118.250
web2

backup

#首先安装keepalived
[root@backup ~]# dnf -y install keepalived

#编辑配置文件
[root@backup ~]# vim /etc/keepalived/keepalived.conf
[root@backup ~]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived
 
global_defs {
   router_id lb02
}
 
vrrp_instance VI_1 {
    state BACKUP
    interface ens33
    virtual_router_id 51
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.118.250
    } 
}
virtual_server 192.168.118.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP

    real_server 192.168.118.129 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }

    real_server 192.168.118.128 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}

#启动服务
[root@backup ~]# systemctl start keepalived.service

编写脚本

master

[root@master ~]# mkdir /scripts
[root@master ~]# cd /scripts/
[root@master scripts]# vim check_haproxy.sh 
#!/bin/bash
haproxy_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bhaproxy\b'|wc -l)
if [ $haproxy_status -lt 1 ];then
    systemctl stop keepalived
fi

[root@master scripts]# vim notify.sh
#!/bin/bash
VIP=$2
case "$1" in
master)
        haproxy_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bhaproxy\b'|wc -l)
        if [ $haproxy_status -lt 1 ];then
                systemctl start haproxy
        fi
;;
backup)
        haproxy_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bhaproxy\b'|wc -l)
        if [ $haproxy_status -gt 0 ];then
                systemctl stop haproxy
        fi
;;
esac

[root@master scripts]# chmod +x check_haproxy.sh notify.sh
[root@master scripts]# ll
total 8
-rwxr-xr-x 1 root root 145 Oct 10 00:32 check_haproxy.sh
-rwxr-xr-x 1 root root 328 Oct 10 00:38 notify.sh

backup

[root@backup ~]# mkdir /scripts
[root@backup ~]# cd /scripts/
[root@backup scripts]# scp root@192.168.118.129:/scripts/notify.sh .
The authenticity of host '192.168.118.129 (192.168.118.129)' can't be established.
ECDSA key fingerprint is SHA256:+RwKWt1ErJuzJKcNeLslD46lbAtIO3wmNQk9BhIrtxs.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '192.168.118.129' (ECDSA) to the list of known hosts.
root@192.168.118.129's password: 
notify.sh                                               100%  328   353.0KB/s   00:00    
[root@backup scripts]# ll
total 4
-rwxr-xr-x 1 root root 328 Oct 10 00:41 notify.sh

配置keepalived加入监控脚本的配置

master

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

global_defs {
   router_id lb01
}

vrrp_script haproxy_check {                  #添加这块
    script "/scripts/check_haproxy.sh"
    interval 1
    weight -20
}

vrrp_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.118.250
    }  
    track_script {                     #添加这块
        haproxy_check
    }
    notify_master "/scripts/notify.sh master 192.168.118.250"
}
virtual_server 192.168.118.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP

    real_server 192.168.118.129 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }

    real_server 192.168.118.128 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}

#重启服务
[root@master ~]# systemctl restart keepalived.service

backup

backup无需检测nginx是否正常，当升级为MASTER时启动nginx，当降级为BACKUP时关闭

[root@backup ~]# vim /etc/keepalived/keepalived.conf
onfiguration File for keepalived
 
global_defs {
   router_id lb02
}
 
vrrp_instance VI_1 {
    state BACKUP
    interface ens33
    virtual_router_id 51
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.118.250
    }
    notify_master "/scripts/notify.sh master 192.168.118.250"    #只需添加此行
#   notify_backup "/scripts/notify.sh backup 192.168.118.250"
}
virtual_server 192.168.118.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP

    real_server 192.168.118.129 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }

    real_server 192.168.118.128 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}

#重启服务
[root@backup ~]# systemctl restart keepalived.service

测试

模拟haproxy服务故障

master

[root@master ~]# curl 192.168.118.250
web1
[root@master ~]# curl 192.168.118.250
web2
[root@master ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:0c:29:b5:9a:13 brd ff:ff:ff:ff:ff:ff
    inet 192.168.118.129/24 brd 192.168.118.255 scope global dynamic noprefixroute ens33
       valid_lft 1404sec preferred_lft 1404sec
    inet 192.168.118.250/32 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:feb5:9a13/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
       
[root@master ~]# systemctl stop haproxy.service
[root@master ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:0c:29:b5:9a:13 brd ff:ff:ff:ff:ff:ff
    inet 192.168.118.129/24 brd 192.168.118.255 scope global dynamic noprefixroute ens33
       valid_lft 1322sec preferred_lft 1322sec
    inet6 fe80::20c:29ff:feb5:9a13/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

backup获得vip

[root@backup ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:0c:29:16:02:99 brd ff:ff:ff:ff:ff:ff
    inet 192.168.118.128/24 brd 192.168.118.255 scope global dynamic noprefixroute ens33
       valid_lft 1328sec preferred_lft 1328sec
    inet 192.168.118.250/32 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe16:299/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
[root@backup ~]# curl 192.168.118.250
web1
[root@backup ~]# curl 192.168.118.250
web2
[root@backup ~]# curl 192.168.118.250
web1
[root@backup ~]# curl 192.168.118.250
web2