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Keepalived实现Httpd负载均衡机高可用

小半 • • 操作系统 • 阅读 164

导读：本篇文章讲解 Keepalived实现Httpd负载均衡机高可用，希望对大家有帮助，欢迎收藏，转发！站点地址：www.bmabk.com

一、keepalived是什么？

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

二、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
  • 作为系统网络服务的高可用性（failover）

三、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。

那么，什么是VRRP呢？

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。

四、keepalived工作原理描述

Keepalived高可用对之间是通过VRRP通信的，因此，我们从 VRRP开始了解起：

  1. VRRP,全称 Virtual Router Redundancy Protocol,中文名为虚拟路由冗余协议，VRRP的出现是为了解决静态路由的单点故障。
  2. VRRP是通过一种竟选协议机制来将路由任务交给某台 VRRP路由器的。
  3. VRRP用 IP多播的方式（默认多播地址（224.0_0.18))实现高可用对之间通信。
  4. 工作时主节点发包，备节点接包，当备节点接收不到主节点发的数据包的时候，就启动接管程序接管主节点的开源。备节点可以有多个，通过优先级竞选，但一般 Keepalived系统运维工作中都是一对。
  5. VRRP使用了加密协议加密数据，但Keepalived官方目前还是推荐用明文的方式配置认证类型和密码。

介绍完 VRRP,接下来我再介绍一下 Keepalived服务的工作原理：

Keepalived高可用是通过 VRRP 进行通信的， VRRP是通过竞选机制来确定主备的，主的优先级高于备，因此，工作时主会优先获得所有的资源，备节点处于等待状态，当主挂了的时候，备节点就会接管主节点的资源，然后顶替主节点对外提供服务。

在 Keepalived 服务之间，只有作为主的服务器会一直发送 VRRP 广播包,告诉备它还活着，此时备不会枪占主，当主不可用时，即备监听不到主发送的广播包时，就会启动相关服务接管资源，保证业务的连续性.接管速度最快可以小于1秒。

keepalived高可用架构图

在这里插入图片描述

五、keepalived实现httpd负载均衡机高可用

环境说明

系统信息 主机名 IP
centos7 master 192.168.91.140
centos7 slave 192.168.91.147

本次高可用虚拟IP（VIP）地址暂定为 192.168.91.250

keepalived安装
配置主keepalived

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

// 配置网络源
[root@master ~]# curl -o /etc/yum.repos.d/CentOS7-Base-163.repo http://mirrors.163.com/.help/CentOS7-Base-163.repo
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--100  1572  100  1572    0     0   3915      0 --:--:-- --:--:-- --:--:--  3930
[root@master ~]# sed -i 's/\$releasever/7/g' /etc/yum.repos.d/CentOS7-Base-163.repo
[root@master ~]# sed -i 's/^enabled=.*/enabled=1/g' /etc/yum.repos.d/CentOS7-Base-163.repo

// 安装工具
[root@master ~]# yum -y install epel-release vim wget gcc gcc-c++

// 安装keepalived
[root@master ~]# yum -y install keepalived
[root@master ~]# rpm -ql keepalived
/etc/keepalived     //配置目录
/etc/keepalived/keepalived.conf     //此为主配置文件
/etc/sysconfig/keepalived
/usr/bin/genhash
/usr/lib/systemd/system/keepalived.service      //此为服务控制文件
/usr/libexec/keepalived
/usr/sbin/keepalived
/usr/share/doc/keepalived-1.3.5

用同样的方法在备服务器上安装keepalived

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

// 配置网络源
[root@slave ~]# curl -o /etc/yum.repos.d/CentOS7-Base-163.repo http://mirrors.163.com/.help/CentOS7-Base-163.repo
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--100  1572  100  1572    0     0  14269      0 --:--:-- --:--:-- --:--:-- 14422
[root@slave ~]# sed -i 's/\$releasever/7/g' /etc/yum.repos.d/CentOS7-Base-163.repo
[root@slave ~]# sed -i 's/^enabled=.*/enabled=1/g' /etc/yum.repos.d/CentOS7-Base-163.repo

// 安装工具
[root@slave ~]# yum -y install epel-release vim wget gcc gcc-c++

//安装keepalived
[root@slave ~]# yum -y install keepalived

在主备机上分别安装httpd
在master上安装httpd

[root@master ~]# yum -y install httpd
[root@master ~]# cd /var/www/html/
[root@master html]# ls
[root@master html]# echo "amu" > index.html
[root@master html]# systemctl start httpd
[root@master html]# systemctl enable --now httpd
Created symlink from /etc/systemd/system/multi-user.target.wants/httpd.service to /usr/lib/systemd/system/httpd.service.
[root@master html]# curl 127.0.0.1
amu
[root@master html]# ss -antl
State      Recv-Q Send-Q Local Address:Port               Peer Address:Port              
LISTEN     0      128     *:22                  *:*                  
LISTEN     0      100    127.0.0.1:25                  *:*                  
LISTEN     0      128    :::80                 :::*                  
LISTEN     0      128    :::22                 :::*                  
LISTEN     0      100       ::1:25                 :::*

在slave上安装httpd

[root@slave ~]# yum -y install httpd
[root@slave ~]# cd /var/www/html/
[root@slave html]# ls
[root@slave html]# echo "gf" > index.html
[root@slave html]# systemctl start httpd
[root@slave html]# systemctl enable --now httpd
Created symlink from /etc/systemd/system/multi-user.target.wants/httpd.service to /usr/lib/systemd/system/httpd.service.
[root@slave html]# curl 127.0.0.1
gf
[root@slave html]# ss -antl
State      Recv-Q Send-Q Local Address:Port               Peer Address:Port              
LISTEN     0      128     *:22                  *:*                  
LISTEN     0      100    127.0.0.1:25                  *:*                  
LISTEN     0      128    :::80                 :::*                  
LISTEN     0      128    :::22                 :::*                  
LISTEN     0      100       ::1:25                 :::*

在浏览器上访问试试，确保master上的httpd服务能够正常访问
在这里插入图片描述
keepalived配置
配置主keepalived

[root@master html]# vim /etc/keepalived/keepalived.conf 
[root@master html]# 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 52
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass amu
    }
    virtual_ipaddress {
        192.168.91.250
    }
}

virtual_server 192.168.91.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP

    real_server 192.168.91.140 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }

    real_server 192.168.91.147 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}

// 重启keepalived
[root@master html]# systemctl restart keepalived
[root@master html]# systemctl enable --now keepalived
Created symlink from /etc/systemd/system/multi-user.target.wants/keepalived.service to /usr/lib/systemd/system/keepalived.service.

配置备keepalived

[root@slave html]# cd
[root@slave ~]# vim /etc/keepalived/keepalived.conf 
[root@slave ~]# 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 gf
    }
    virtual_ipaddress {
        192.168.91.250
    }
}

virtual_server 192.168.91.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP

    real_server 192.168.91.140 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }

    real_server 192.168.91.147 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}

[root@slave ~]# systemctl restart keepalived
[root@slave ~]# systemctl enable --now keepalived
Created symlink from /etc/systemd/system/multi-user.target.wants/keepalived.service to /usr/lib/systemd/system/keepalived.service.

查看VIP在哪里
在MASTER上查看

[root@master html]# cd
[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 pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:51:f0:f3 brd ff:ff:ff:ff:ff:ff
    inet 192.168.91.140/24 brd 192.168.91.255 scope global noprefixroute dynamic ens33
       valid_lft 1786sec preferred_lft 1786sec
    inet 192.168.91.250/32 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::3d97:49cb:78ab:4516/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

在SLAVE上查看

[root@slave ~]# 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 pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:92:a7:4c brd ff:ff:ff:ff:ff:ff
    inet 192.168.91.147/24 brd 192.168.91.255 scope global noprefixroute dynamic ens33
       valid_lft 1494sec preferred_lft 1494sec
    inet 192.168.91.250/32 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::63d3:24b8:633e:63e6/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

修改内核参数，开启监听VIP功能
此步可做可不做，该功能可用于仅监听VIP的时候
在master上修改内核参数

[root@master ~]# echo 'net.ipv4.ip_nonlocal_bind = 1' >>/etc/sysctl.conf
[root@master ~]# sysctl -p
net.ipv4.ip_nonlocal_bind = 1
[root@master ~]# cat /proc/sys/net/ipv4/ip_nonlocal_bind 
1

在slave上修改内核参数

[root@slave ~]# echo 'net.ipv4.ip_nonlocal_bind = 1' >>/etc/sysctl.conf
[root@slave ~]# sysctl -p
net.ipv4.ip_nonlocal_bind = 1
[root@slave ~]# cat /proc/sys/net/ipv4/ip_nonlocal_bind 
1

让keepalived监控httpd负载均衡机
keepalived通过脚本来监控httpd负载均衡机的状态
在master上编写脚本

// 创建脚本目录
[root@master ~]# mkdir /scripts
[root@master ~]# cd /scripts/
[root@master scripts]# vim check_h.sh
#!/bin/bash

httpd_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bhttpd\b'|wc -l)
if [ $httpd_status -lt 1 ];then
    systemctl stop keepalived
fi

// 给执行权限
[root@master scripts]# chmod +x check_h.sh 
[root@master scripts]# ll
总用量 4
-rwxr-xr-x. 1 root root 143 10月 21 16:33 check_h.sh

[root@master scripts]# vim notify.sh
[root@master 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" 2781551316@qq.com
}
case "$1" in
  master)
        httpd_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bhttpd\b'|wc -l)
        if [ $httpd_status -lt 1 ];then
            systemctl start httpd
        fi
        sendmail
  ;;
  backup)
        httpd_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bhttpd\b'|wc -l)
        if [ $httpd_status -gt 0 ];then
            systemctl stop httpd
        fi
  ;;
  *)
        echo "Usage:$0 master|backup VIP"
  ;;
esac

[root@master scripts]# chmod +x notify.sh 
[root@master scripts]# ll
总用量 8
-rwxr-xr-x. 1 root root 143 10月 21 16:33 check_h.sh
-rwxr-xr-x. 1 root root 663 10月 21 16:37 notify.sh

在slave上编写脚本

[root@slave ~]# mkdir /scripts
[root@slave ~]# cd /scripts/
[root@slave scripts]# vim notify.sh 
[root@slave 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" 2781551316@qq.com
}
case "$1" in
  master)
        httpd_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bhttpd\b'|wc -l)
        if [ $httpd_status -lt 1 ];then
            systemctl start httpd
        fi
        sendmail
  ;;
  backup)
        httpd_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bhttpd\b'|wc -l)
        if [ $httpd_status -gt 0 ];then
            systemctl stop httpd
        fi
  ;;
  *)
        echo "Usage:$0 master|backup VIP"
  ;;
esac

[root@slave scripts]# chmod +x notify.sh
[root@slave scripts]# ll
总用量 4
-rwxr-xr-x. 1 root root 663 10月 21 16:42 notify.sh

此处的脚本名称应避免与服务名相同，推荐用服务名的首字母代替，如check_h，不要给脚本起名check_httpd

配置keepalived加入监控脚本的配置
配置主keepalived

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

global_defs {
   router_id lb01
}

vrrp_script httpd_check {
    script "/scripts/check_h.sh"
    interval 1
    weight -20
}

vrrp_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 52
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass amu
    }
    virtual_ipaddress {
        192.168.91.250
    }
    track_script {
        httpd_check
    }
    notify_master "/scripts/notify.sh master 192.168.91.250"
    notify_backup "/scripts/notify.sh backup 192.168.91.250"
}

virtual_server 192.168.91.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP

    real_server 192.168.91.140 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }

    real_server 192.168.91.147 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}

[root@master scripts]# systemctl restart keepalived

配置备keepalived

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

[root@slave scripts]# vim /etc/keepalived/keepalived.conf 
[root@slave scripts]# 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 gf
    }
    virtual_ipaddress {
        192.168.91.250
    }
    notify_master "/scripts/notify.sh master 192.168.91.250"
    notify_backup "/scripts/notify.sh backup 192.168.91.250"
}

virtual_server 192.168.91.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP

    real_server 192.168.91.140 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }

    real_server 192.168.91.147 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}

[root@slave scripts]# systemctl restart keepalived

模拟主服务器宕机

[root@master ~]# systemctl stop  keepalived
[root@master ~]# systemctl stop httpd

在这里插入图片描述
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