KeepAlived双主模式高可用集群

一、keepalived简介keepalived是vrrp协议的实现，原生设计目的是为了高可用ipvs服务，keepalived能够配置文件中的定义生成ipvs规则，并能够对各RS的健康状态进行检测；通过共用的虚拟IP地址对外提供服务；每个热备组内同一时刻只有一台主服务器提供服务，其他服务器处于冗余状态，若当前在线的服务器宕机，其虚拟IP地址将会被其他服务器接替（优先级决定接替顺序），实现高可用为后端主机提供服务。

二、keepalived组件Keepalived组件介绍

core:keepalived核心组件，主进程的启动和维护，全局配置等vrrp stack:keepalived是基于vrrp协议实现高可用vps服务，vrrp则为相关子进程为其提供服务check:检测keepalived的健康状态相关进程。

system call:系统调用watch dog:监控check和vrrp进程的看管者，check负责检测器子进程的健康状态，当其检测到master上的服务不可用时则通告vrrp将其转移至backup服务器上。

三、keepalived配置实验拓扑图如下：

keepalived主配置文件主要分为三段：global_defs、vrrp_instance、virtual_ip address,如下详解：示例：编辑/etc/keepalived/keepalived.conf配置文件，将此文件负责给另一个台keepalived服务器，相应的修改其优先级及其state状态信息

! Configuration File for keepalived global_defs { notification_email { root@localhost } notification_email_from kaadmin@chen.com smtp_server 127.0.0.1 smtp_connect_timeout 30 router_id centos7s vrrp_mcast_group4 224.0.4.18 } vrrp_script chk_down { script “[[ -f /etc/keepalived/down ]] && exit 1 || exit 0” interval 2 weight -5 } vrrp_script chk_httpd { script “killall -0 httpd” interval 2 weight -5 } vrrp_instance VI_1 { state MASTER interface eno16777736 virtual_router_id 51 priority 100 advert_int 1 authentication { auth_type PASS auth_pass frSAmesXYSSFmw } virtual_ipaddress { 10.1.10.7 dev eno16777736 labeleno16777736:0 } track_script { chk_down chk_httpd } notify_master “/etc/keepalived/notify.sh master” notify_backup “/etc/keepalived/notify.sh backup” notify_fault “/etc/keepalived/notify.sh fault” } 双主模式:互为主备 vrrp_instance VI_1 { #vrrp实例1 state MASTER #keepalived当前的状态信息，master为主，slave为从 interface eno16777736 #监听的网卡接口 virtual_router_id 151 #虚拟路由的id号，范围为0-255 priority 100 #当前keepalived的优先级，数字越大，优先级越高 advert_int 1 # authentication { #authentication认证模块 auth_type PASS #验证类型 auth_pass frSAmesXYSSFmw #密码 } virtual_ipaddress { #设置虚拟ip地址，此处为VIP：10.1.10.7 10.1.10.7 dev eno16777736 labeleno16777736:0 } track_script { #调用检测测监本 chk_down chk_httpd } notify_master “/etc/keepalived/notify.sh master” notify_backup “/etc/keepalived/notify.sh backup” notify_fault “/etc/keepalived/notify.sh fault” } vrrp_instance VI_2 { #实例二，同上 state BACKUP interface eno16777736 virtual_router_id 152 priority 98 advert_int 1 authentication { auth_type PASS auth_pass frSAmesXYSSymw } virtual_ipaddress { 10.1.10.77 dev eno16777736 labeleno16777736:1 } track_script { chk_down chk_httpd } notify_master “/etc/keepalived/notify.sh master” notify_backup “/etc/keepalived/notify.sh backup” notify_fault “/etc/keepalived/notify.sh fault” }

使用lvs-dr相同的方法配置Real Server1/Real Server2:echo 2 >/proc/sys/net/ipv4/conf/all/arp_announce echo 2 >/proc/sys/net/ipv4/conf/lo/arp_announce echo 1 >/proc/sys/net/ipv4/conf/all/arp_announce echo 1 >/proc/sys/net/ipv4/conf/lo/arp_announce ifconfig lo:0 10.1.10.7 netmask 255.255.255.255 broadcast 10.1.10.7 route add -host 10.1.10.7 dev lo:0

分别给Real Server提供测试页面及其给keepalived节点配置应急响应页面echo “RS1”>/var/www/html/index.html echo“sorry server”>/web/index.html

配置成功后启动keepalived及其后端主机，在keepalived节点上查看其相应的ipvs信息：