Keepalived高可用

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所属分类:linux技术
摘要

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高可用

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:http://www.keepalived.org/

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

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。

keepalived原理

Keepalived高可用

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:

  • 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。
  • 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。
  • 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资源。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。

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。

演示:

实验环境:

主机名 系统 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主节点 [root@lxmaster ~]# nmcli  eth0: 已连接 到 eth0         "VMware VMXNET3"         ethernet (vmxnet3), 00:0C:29:E7:7F:F3, 硬件, mtu 1500         ip4 默认         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备份节点 [root@lxbackup ~]# nmcli  ens160: 已连接 到 ens160         "VMware VMXNET3"         ethernet (vmxnet3), 00:0C:29:88:DC:C6, 硬件, mtu 1500         ip4 默认         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 

关闭防火墙

#Master主节点 [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备份节点 [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 ... 

安装keeppalived

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

安装nginx

#Master主节点 [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节点 [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. 

测试

#Master主节点 [root@lxmaster ~]# curl localhost master node #backup节点 [root@lxbackup ~]# curl localhost backup node 

配置keepalived

#Master主节点 [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 		} 	} } #重启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备份节点 [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  连接已成功激活(D-Bus 活动路径:/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 ... 

编写脚本

#Master主节点 [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" abc@163.com } case "$1" in    master) 	nginx_status=$(ps -ef|grep -Ev "grep|$0"|grep 'bnginxb'|wc -l) 	if [ $nginx_status -lt 1 ];then 		systemctl start nginx 	fi 	sendmail ;;    backup)								         	nginx_status=$(ps -ef|grep -Ev "grep|$0"|grep 'bnginxb'|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主节点 [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节点 [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  

模拟故障

[root@lxmaster ~]# systemctl restart nginx.service  [root@lxmaster ~]# systemctl enable nginx #此时查看备份节点80端口暂未开启 [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                                        [::]:*                   

Keepalived高可用

[root@lxmaster ~]# systemctl stop nginx.service [root@lxmaster ~]# systemctl restart keepalived.service #再次查看备份节点80端口已开启  [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                                        [::]:*    

Keepalived高可用