Keepalived高可用-有解無憂

keepalived高可用

keepalived是什么？

Keepalived 軟體起初是專為LVS負載均衡軟體設計的，用來管理并監控LVS集群系統中各個服務節點的狀態，后來又加入了可以實作高可用的VRRP功能，因此，Keepalived除了能夠管理LVS軟體外，還可以作為其他服務（例如：Nginx、Haproxy、MySQL等）的高可用解決方案軟體，

Keepalived軟體主要是通過VRRP協議實作高可用功能的，VRRP是Virtual Router RedundancyProtocol(虛擬路由器冗余協議）的縮寫，VRRP出現的目的就是為了解決靜態路由單點故障問題的，它能夠保證當個別節點宕機時，整個網路可以不間斷地運行，

所以，Keepalived 一方面具有配置管理LVS的功能，同時還具有對LVS下面節點進行健康檢查的功能，另一方面也可實作系統網路服務的高可用功能，

Keepalived官網：http://www.keepalived.org/

Keepalived的重要功能

keepalived 有三個重要的功能，分別是：

管理LVS負載均衡軟體
實作LVS集群節點的健康檢查
作為系統網路服務的高可用性

keepalived高可用故障轉移的原理

Keepalived 高可用服務之間的故障切換轉移，是通過 VRRP (Virtual Router Redundancy Protocol ,虛擬路由器冗余協議）來實作的，

在 Keepalived 服務正常作業時，主 Master 節點會不斷地向備節點發送（多播的方式）心跳訊息，用以告訴備 Backup 節點自己還活看，當主 Master 節點發生故障時，就無法發送心跳訊息，備節點也就因此無法繼續檢測到來自主 Master 節點的心跳了，于是呼叫自身的接管程式，接管主 Master 節點的 IP 資源及服務，而當主 Master 節點恢復時，備 Backup 節點又會釋放主節點故障時自身接管的IP資源及服務，恢復到原來的備用角色，

keepalived原理

Keepalived高可用對之間是通過VRRP通信的，因此，我們從 VRRP開始了解起：

VRRP,全稱 Virtual Router Redundancy Protocol,中文名為虛擬路由冗余協議，VRRP的出現是為了解決靜態路由的單點故障，
VRRP是通過一種竟選協議機制來將路由任務交給某臺 VRRP路由器的，
VRRP用 IP多播的方式（默認多播地址（224.0.0.18))實作高可用對之間通信，
作業時主節點發包，備節點接包，當備節點接收不到主節點發的資料包的時候，就啟動接管程式接管主節點的資源，備節點可以有多個，通過優先級競選，但一般 Keepalived系統運維作業中都是一對，
VRRP使用了加密協議加密資料，但Keepalived官方目前還是推薦用明文的方式配置認證型別和密碼，

介紹完 VRRP,接下來我再介紹一下 Keepalived服務的作業原理：

Keepalived高可用是通過 VRRP 進行通信的， VRRP是通過競選機制來確定主備的，主的優先級高于備，因此，作業時主會優先獲得所有的資源，備節點處于等待狀態，當主掛了的時候，備節點就會接管主節點的資源，然后頂替主節點對外提供服務，

在 Keepalived 服務之間，只有作為主的服務器會一直發送 VRRP 廣播包,告訴備它還活著，此時備不會槍占主，當主不可用時，即備監聽不到主發送的廣播包時，就會啟動相關服務接管資源，保證業務的連續性.接管速度最快可以小于1秒，

演示：

實驗環境：

主機名	系統	IP	VIP
lxmaster.example.com	Red Hat Enterprise Linux release 8.2	192.168.100.110/24	192.168.100.200/32
lxbackup.example.com	Red Hat Enterprise Linux release 8.2	192.168.100.120/24

配置IP

#Master主節點
[root@lxmaster ~]# nmcli 
eth0: 已連接 到 eth0
        "VMware VMXNET3"
        ethernet (vmxnet3), 00:0C:29:E7:7F:F3, 硬體, mtu 1500
        ip4 默認
        inet4 192.168.100.110/24
        route4 192.168.100.0/24
        route4 0.0.0.0/0
        inet6 fe80::20c:29ff:fee7:7ff3/64
        route6 fe80::/64
        route6 ff00::/8
#backup備份節點
[root@lxbackup ~]# nmcli 
ens160: 已連接 到 ens160
        "VMware VMXNET3"
        ethernet (vmxnet3), 00:0C:29:88:DC:C6, 硬體, mtu 1500
        ip4 默認
        inet4 192.168.100.120/24
        route4 192.168.100.0/24
        route4 0.0.0.0/0
        inet6 fe80::20c:29ff:fe88:dcc6/64
        route6 fe80::/64
        route6 ff00::/8

關閉防火墻

#Master主節點
[root@lxmaster ~]# systemctl stop firewalld.service 
[root@lxmaster ~]# systemctl disable firewalld.service 
Removed /etc/systemd/system/multi-user.target.wants/firewalld.service.
Removed /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service.
[root@lxmaster ~]# vim /etc/selinux/
[root@lxmaster ~]# vim /etc/selinux/config 
...
SELINUX=disabled
...
#backup備份節點
[root@lxbackup ~]# systemctl stop firewalld.service 
[root@lxbackup ~]# systemctl disable firewalld.service 
Removed /etc/systemd/system/multi-user.target.wants/firewalld.service.
Removed /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service.
[root@lxbackup ~]# vim /etc/selinux/config 
...
SELINUX=disabled
...

安裝keeppalived

#Mster主節點
[root@lxmaster ~]# yum -y install vim wget gcc gcc-c++
[root@lxmaster ~]# yum -y install keepalived
#backup節點
[root@lxbackup ~]# yum -y install vim wget gcc gcc-c++
[root@lxbackup ~]# yum -y install keepalived

安裝nginx

#Master主節點
[root@lxmaster ~]# yum -y install nginx
[root@lxmaster ~]# echo " master node" > /usr/share/nginx/html/index.html 
[root@lxmaster ~]# systemctl restart nginx.service 
[root@lxmaster ~]# systemctl enable nginx.service 
Created symlink /etc/systemd/system/multi-user.target.wants/nginx.service → /usr/lib/systemd/system/nginx.service.
#backup節點
[root@lxbackup ~]# yum -y install nginx
[root@lxbackup ~]# echo "backup node" > /usr/share/nginx/html/index.html 
[root@lxbackup ~]# systemctl enable --now nginx.service 
Created symlink /etc/systemd/system/multi-user.target.wants/nginx.service → /usr/lib/systemd/system/nginx.service.

測驗

#Master主節點
[root@lxmaster ~]# curl localhost
master node
#backup節點
[root@lxbackup ~]# curl localhost
backup node

配置keepalived

#Master主節點
[root@lxmaster ~]# cd /etc/keepalived/
[root@lxmaster keepalived]# cp keepalived.conf keepalived.conf.bak
[root@lxmaster keepalived]# vim keepalived.conf
! Configuration File for keepalived

global_defs {
	router id lx01
}

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 {
    		192.168.100.200
	}
}

virtual_server 192.168.100.200 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP

    real_server 192.168.100.110 80 {
        weight 1
	TCP_CHECK{
		connect_port 80
		connect_timeout 3
		nb_get_retry 3
		delay_before_retry 3

    }
}

    real_server 192.168.200.3 1358 {
        weight 1
	TCP_CHECK { 
	    connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
		}
	}
}
#重啟keepalived
[root@lxmaster keepalived]# systemctl restart keepalived.service 
[root@lxmaster keepalived]# systemctl enable keepalived.service 
Created symlink /etc/systemd/system/multi-user.target.wants/keepalived.service → /usr/lib/systemd/system/keepalived.service.

#backup備份節點
[root@lxbackup ~]# cd /etc/keepalived/
[root@lxbackup keepalived]# cp keepalived.conf keepalived.conf.bak
[root@lxbackup keepalived]# vim keepalived.conf
! Configuration File for keepalived
global_defs {
   router_id lx02
}

vrrp_instance VI_1 {
    state BACKUP
    interface ens160
    virtual_router_id 51
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.100.200
    }
}
virtual_server 192.168.100.200 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP

    real_server 192.168.100.110 80 {
        weight 1
        TCP_CHECK {
	    connect_port 80
            connect_timeout 3
	    nb_get_retry 3
            delay_before_retry 3
        }
    }


    real_server 192.168.100.120 80 {
        weight 1
        TCP_CHECK { 
	    connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}
[root@lxbackup keepalived]# systemctl restart keepalived.service 
[root@lxbackup keepalived]# systemctl enable keepalived.service 
Created symlink /etc/systemd/system/multi-user.target.wants/keepalived.service → /usr/lib/systemd/system/keepalived.service.

在master中配置VIP

[root@lxmaster ~]# vim /etc/sysconfig/network-scripts/ifcfg-eth0 
...
IPADDR1=192.168.100.200
PREFIX1=32
[root@lxmaster ~]# systemctl restart NetworkManager
[root@lxmaster ~]# nmcli connection up eth0 
連接已成功激活（D-Bus 活動路徑：/org/freedesktop/NetworkManager/ActiveConnection/4）
[root@lxmaster ~]# ip a
...
eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:0c:29:e7:7f:f3 brd ff:ff:ff:ff:ff:ff
    inet 192.168.100.110/24 brd 192.168.100.255 scope global noprefixroute eth0
       valid_lft forever preferred_lft forever
    inet 192.168.100.200/32 scope global noprefixroute eth0
       valid_lft forever preferred_lft forever
...

撰寫腳本

#Master主節點
[root@lxmaster scripts]# vim check.sh
#!/bin/bash
nginx_status=`ps -ef | grep -v "grep" | grep "nginx" | wc -l`
if [ $nginx_status -lt 1 ];then
        systemctl stop keepalived
fi
[root@lxmaster scripts]# vim 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" [email protected]
}
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@lxmaster scripts]# chmod +x check.sh 
[root@lxmaster scripts]# chmod +x notify.sh

再次配置keepalived

#Master主節點
[root@lxmaster scripts]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived

global_defs {
	router id lx01
}

vrrp_script nginx_check { 
    script "/scripts/check.sh"
    interval 10
    weight -20
}

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 {
    		192.168.100.200
	}
track_script{
	nginx_check
	}
notify_master "/scripts/notify.sh master 192.168.100.200"
notify_backup "/scripts/notify.sh backup 192.168.100.200"
}

virtual_server 192.168.100.200 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP

    real_server 192.168.100.110 80 {
        weight 1
	TCP_CHECK{
		connect_port 80
		connect_timeout 3
		nb_get_retry 3
		delay_before_retry 3

    }
}

    real_server 192.168.200.3 1358 {
        weight 1
	TCP_CHECK { 
	    connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
		}
	}
}
[root@lxmaster scripts]# systemctl restart keepalived.service 

#backup節點
[root@lxbackup ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
   router_id lx02
}
vrrp_script nginx_check { 
    script "/scripts/check.sh"
    interval 10
    weight -20
}
vrrp_instance VI_1 {
    state BACKUP
    interface ens160
    virtual_router_id 51
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.100.200
    }
	notify_master "/scripts/notify.sh master 192.168.100.200"
	notify_backup "/scripts/notify.sh backup 192.168.100.200"
}
virtual_server 192.168.100.200 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP

    real_server 192.168.100.110 80 {
        weight 1
        TCP_CHECK {
	    connect_port 80
            connect_timeout 3
	    nb_get_retry 3
            delay_before_retry 3
        }
    }


    real_server 192.168.100.120 80 {
        weight 1
        TCP_CHECK { 
	    connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}
[root@lxbackup ~]# systemctl restart keepalived.service

模擬故障

[root@lxmaster ~]# systemctl restart nginx.service 
[root@lxmaster ~]# systemctl enable nginx
#此時查看備份節點80埠暫未開啟
[root@lxbackup ~]# ss -tanl 
State                Recv-Q                Send-Q                               Local Address:Port                               Peer Address:Port               
LISTEN               0                     128                                        0.0.0.0:22                                      0.0.0.0:*                  
LISTEN               0                     5                                        127.0.0.1:631                                     0.0.0.0:*                  
LISTEN               0                     128                                           [::]:22                                         [::]:*                  
LISTEN               0                     5                                            [::1]:631                                        [::]:*

[root@lxmaster ~]# systemctl stop nginx.service
[root@lxmaster ~]# systemctl restart keepalived.service
#再次查看備份節點80埠已開啟 
[root@lxbackup ~]# ss -tanl
State                Recv-Q                Send-Q                               Local Address:Port                               Peer Address:Port               
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                     5                                        127.0.0.1:631                                     0.0.0.0:*                  
LISTEN               0                     128                                           [::]:80                                         [::]:*                  
LISTEN               0                     128                                           [::]:22                                         [::]:*                  
LISTEN               0                     5                                            [::1]:631                                        [::]:*

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標籤：Linux

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