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。

官网：http://www.keepalived.org/

功能

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）

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 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。

• 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。

• 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。

• 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。

• 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。

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。

部署

## master ##
关闭防火墙selinux
[root@localhost ~]# hostnamectl set-hostname master
[root@localhost ~]# bash
[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 ~]# vim /etc/selinux/config 
[root@master ~]# setenforce 0
[root@master ~]# reboot 
[root@master ~]# getenforce 
Disabled

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
100  1572  100  1572    0     0   4837      0 --:--:-- --:--:-- --:--:--  4851
[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

安装相关组件
[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  //主配置文件
/etc/sysconfig/keepalived
/usr/bin/genhash
/usr/lib/systemd/system/keepalived.service  //服务控制文件
/usr/libexec/keepalived
/usr/sbin/keepalived   //命令存放位置


## slave ##
关闭防火墙selinux
[root@localhost ~]# hostnamectl set-hostname slave
[root@localhost ~]# bash
[root@slave ~]# systemctl disable --now firewalld.service
Removed symlink /etc/systemd/system/multi-user.target.wants/firewalld.service.
Removed symlink /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service.
[root@slave ~]# vim /etc/selinux/config 
[root@slave ~]# setenforce 0
[root@slave ~]# reboot 
[root@slave ~]# getenforce 
Disabled

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
100  1572  100  1572    0     0   2335      0 --:--:-- --:--:-- --:--:--  2332
[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

安装相关组件
[root@slave ~]# yum -y install epel-release vim wget gcc gcc-c++

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

## master ##
在master上安装httpd
[root@master ~]# yum -y install httpd

设置开机自启
[root@master ~]# 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 ~]# systemctl status httpd
● httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; enabled; vendor preset: disabled)
   Active: active (running) since 五 2021-10-22 00:18:50 EDT; 8s ago
     Docs: man:httpd(8)
           man:apachectl(8)
 Main PID: 13792 (httpd)
   Status: "Processing requests..."
   CGroup: /system.slice/httpd.service
           ├─13792 /usr/sbin/httpd -DFOREGROUND
           ├─13793 /usr/sbin/httpd -DFOREGROUND
           ├─13794 /usr/sbin/httpd -DFOREGROUND
           ├─13795 /usr/sbin/httpd -DFOREGROUND
           ├─13796 /usr/sbin/httpd -DFOREGROUND
           └─13797 /usr/sbin/httpd -DFOREGROUND

10月 22 00:18:50 master systemd[1]: Starting The Apache HTTP Server...
10月 22 00:18:50 master httpd[13792]: AH00558: httpd: Could not reliably determ...ge
10月 22 00:18:50 master systemd[1]: Started The Apache HTTP Server.
Hint: Some lines were ellipsized, use -l to show in full.

[root@master ~]# 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                        :::*      

配置网站
[root@master ~]# echo 'master' > /var/www/html/index.html
[root@master ~]# curl 192.168.145.149
master

## slave ##
在slave上安装httpd
[root@slave ~]# yum -y install httpd

设置开机自启
[root@slave ~]# systemctl enable --now httpd
Created symlink from /etc/systemd/system/multi-user.target.wants/httpd.service to /usr/lib/systemd/system/httpd.service.

配置网站
[root@slave ~]# echo 'slave' > /var/www/html/index.html
[root@slave ~]# curl 192.168.145.150
slave
[root@slave ~]# curl 192.168.145.149
master

## master ##
配置主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_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass lll
    }
    virtual_ipaddress {
       192.168.145.250
    }
}

virtual_server 192.168.145.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP

    real_server 192.168.145.149 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }

    real_server 192.168.145.150 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}

重启使配置生效
[root@master ~]# systemctl restart keepalived
[root@master ~]# systemctl enable keepalived
Created symlink from /etc/systemd/system/multi-user.target.wants/keepalived.service to /usr/lib/systemd/system/keepalived.service.

## slave ##
配置备keepalived
[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 eth0
    virtual_router_id 51
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass lll
    }
    virtual_ipaddress {
        192.168.145.250
    }
}

virtual_server 192.168.145.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP

    real_server 192.168.145.149 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }

    real_server 192.168.145.150 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}
使配置生效
[root@slave ~]# systemctl restart keepalived
[root@slave ~]# systemctl enable keepalived
Created symlink from /etc/systemd/system/multi-user.target.wants/keepalived.service to /usr/lib/systemd/system/keepalived.service.

查看VIP
[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:29:20:9e:66 brd ff:ff:ff:ff:ff:ff
    inet 192.168.145.149/24 brd 192.168.145.255 scope global noprefixroute ens33
       valid_lft forever preferred_lft forever
    inet 192.168.145.250/32 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe20:9e66/64 scope link 
       valid_lft forever preferred_lft forever
[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:b4:70:bf brd ff:ff:ff:ff:ff:ff
    inet 192.168.145.150/24 brd 192.168.145.255 scope global noprefixroute ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:feb4:70bf/64 scope link 
       valid_lft forever preferred_lft forever

## master ##
修改内核参数，开启监听VIP功能
[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

## slave ##
[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通过脚本来监控httpd负载均衡机的状态
## master ##
[root@master ~]# mkdir /scripts
[root@master ~]# cd /scripts/
[root@master scripts]# vim check_m.sh
[root@master scripts]# cat check_m.sh 
if [ $httpd_status -lt 1 ];then
    systemctl stop keepalived
fi
[root@master scripts]# chmod +x check_m.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" 593582553@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  65 10月 22 00:34 check_m.sh
-rwxr-xr-x 1 root root 656 10月 22 00:35 notify.sh

## slave ##
[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" 1344933566@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 662 10月 22 00:37 notify.sh

配置keepalived加入监控脚本的配置
## master ##
[root@master scripts]# vim notify.sh
[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    ## 非常重要，标识本机的hostname
}

vrrp_script httpd_check {
    script "/scripts/check_m.sh"  ## 执行的脚本位置
    interval 1   ## 检测时间间隔
    weight -20    ## 如果条件成立则权重减20
}

vrrp_instance VI_1 {
    state MASTER    ## 非常重要，标识主机，备用机为BACKUP
    interface ens33    ## 非常重要，网卡名
    virtual_router_id 52    ## 非常重要，虚拟路由ID号（主备节点要相同）
    priority 100   ## 优先级（0-254），一般主机的大于备机
    advert_int 1   ## 主备信息发送间隔，两个节点必须一致，默认1秒
    authentication {
        auth_type PASS
        auth_pass lll  证匹配，设置认证类型和密码，MASTER和BACKUP必须使用相同的密码才能正常通信
    }
    virtual_ipaddress {  
        192.168.145.250   ##虚拟ip，可以指定多个
    }
    track_script {    ## 检查haproxy健康状况的脚本
        httpd_check
    }
    notify_master "/scripts/notify.sh master 192.168.216.250"
    notify_backup "/scripts/notify.sh backup 192.168.216.250"
}

virtual_server 192.168.145.250 80 {   ####虚拟ip 的详细配置
    delay_loop 6  
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP

    real_server 192.168.145.149 80 {  ## ## 本机的真实ip
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }

    real_server 192.168.145.150 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

## slave  ## 
[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 52
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass lll
    }
    virtual_ipaddress {
        192.168.145.250
    }
    notify_master "/scripts/notify.sh master 192.168.216.250"
    notify_backup "/scripts/notify.sh backup 192.168.216.250"
}

virtual_server 192.168.145.250 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP

    real_server 192.168.145.149 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }

    real_server 192.168.145.150 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 scripts]# systemctl stop  keepalived
[root@master scripts]# systemctl stop httpd