Web集群案例实战 -- Keepalived 实现 web 服务高可用

Keepalived 实现 web 服务高可用

• 前言

前言

本环境是基于 Centos 7.8 系统构建 Keepalived 学习环境
具体构建，请参考 Keepalived 环境部署

环境准备

role	host	ip	keepalive-version	httpd-version
MASTER	node01	192.168.5.11	keepalived-2.0.12	httpd-2.4.6
BACKUP	node02	192.168.5.12	keepalived-2.0.12	httpd-2.4.6
Client	node03	192.168.5.13	----	----

部署 http服务

---node01[root@node01 ~]# yum install httpd -y[root@node01 ~]# echo "`hostname -I` httpd test page..." > /var/www/html/index.html[root@node01 ~]# systemctl start httpd---node02[root@node02 ~]# yum install httpd -y[root@node02 ~]# echo "`hostname -I` httpd test page..." > /var/www/html/index.html[root@node02 ~]# systemctl start httpd

配置 MASTER

[root@node01 ~]# vim /etc/keepalived/keepalived.conf ! Configuration File for keepalivedglobal_defs {   notification_email {     [e-mail]     [e-mail]     [e-mail]   }   notification_email_from [e-mail]   smtp_server 192.168.5.10   smtp_connect_timeout 30   router_id LVS_DEVEL1}vrrp_instance VI_1 {    state MASTER    interface ens33    virtual_router_id 51    priority 200    advert_int 1    authentication {        auth_type PASS        auth_pass 1111    }    virtual_ipaddress {        192.168.5.20    }}[root@node01 ~]# systemctl restart keepalived.service 

配置 BACKUP

[root@node02 ~]# vim /etc/keepalived/keepalived.conf ! Configuration File for keepalivedglobal_defs {   notification_email {     [e-mail]     [e-mail]     [e-mail]   }   notification_email_from [e-mail]   smtp_server 192.168.5.10   smtp_connect_timeout 30   router_id LVS_DEVEL2}vrrp_instance VI_1 {    state BACKUP    interface ens33    virtual_router_id 51    priority 100    advert_int 1    authentication {        auth_type PASS        auth_pass 1111    }    virtual_ipaddress {        192.168.5.20    }}[root@node02 ~]# systemctl restart keepalived.service 

客户端通过 VIP 访问 web 服务

node01 发生故障后

[root@node01 ~]# systemctl stop keepalived.service [root@node01 ~]# ps -ef | grep keepalivedroot      32598  31955  0 10:19 pts/0    00:00:00 grep --color=auto keepalived

此时 node02 成为 MASTER VIP 漂移到了node02！！！

当node01 web 服务发生故障后

[root@node01 ~]# systemctl start keepalived.service [root@node01 ~]# ps -ef | grep keepalivedroot      32611      1  0 10:21 ?        00:00:00 /usr/local/keepalived/sbin/keepalived -Droot      32612  32611  0 10:21 ?        00:00:00 /usr/local/keepalived/sbin/keepalived -Droot      32614  31955  0 10:21 pts/0    00:00:00 grep --color=auto keepalived[root@node01 ~]# systemctl stop httpd[root@node01 ~]# ps -ef | grep httpdroot      32625  31955  0 10:21 pts/0    00:00:00 grep --color=auto httpd

此时 VIP 在node01 上，且node01 web 服务发生故障…

我们可以通过脚本的方式，keepalive 对web服务进行健康检查！以确保服务的高可用性

---node01[root@node01 ~]# vim /etc/keepalived/check_web_server_keepalive.sh#!/bin/bashwhile truedo   http_pid=$(ps -C httpd --no-header | wc -l)   echo $http_pid   if [ ${http_pid} -eq 0 ]   then     systemctl start httpd     sleep 4   fi      http_pid=$(ps -C httpd --no-header | wc -l)   if [ ${http_pid} -eq 0 ]   then      systemctl stop keepalived   fi   sleep 3done[root@node01 ~]# chmod  x /etc/keepalived/check_web_server_keepalive.sh[root@node01 ~]# cd /etc/keepalived/[root@node01 keepalived]# nohup ./check_web_server_keepalive.sh &---node02[root@node02 ~]# vim /etc/keepalived/check_web_server_keepalive.sh#!/bin/bashwhile truedo   http_pid=$(ps -C httpd --no-header | wc -l)   echo $http_pid   if [ ${http_pid} -eq 0 ]   then     systemctl start httpd     sleep 4   fi      http_pid=$(ps -C httpd --no-header | wc -l)   if [ ${http_pid} -eq 0 ]   then      systemctl stop keepalived   fi   sleep 3done[root@node02 ~]# chmod  x /etc/keepalived/check_web_server_keepalive.sh[root@node02 ~]# cd /etc/keepalived/[root@node02 keepalived]# nohup ./check_web_server_keepalive.sh &

测试
node02 停止httpd

[root@node01 ~]# systemctl stop httpd

查看node01 web 服务状态

[root@node01 ~]# systemctl is-active httpdactive

node01 web 服务正常响应！！！

停止node01 keepalived 关闭node02 web 服务

[root@node01 ~]# systemctl stop keepalived[root@node01 ~]# systemctl is-active keepalivedunknown[root@node02 keepalived]# systemctl stop httpd

node01 web 服务正常响应！！！来源：https://www.icode9.com/content-4-879351.html