Keepalived & LVS: 实现web的负载均衡和高可用

1. 环境介绍

A. 192.168.205.111 steppingstone.glinux.top steppingstone
B. 192.168.205.112 rs1.glinux.top rs1
C. 192.168.205.118 rs2.glinux.top rs2
D. 192.168.205.113 ha1.glinux.top ha1
E. 192.168.205.115 ha2.glinux.top ha2
F. alias自定义

　　vim /root/.bashrc

alias echop='for i in `seq 1 $COLUMNS`; do echo -n "+"; done'
alias rs='for i in {1..2}; do ssh rs$i'
alias ha='for i in {1..2}; do ssh ha$i'

2. LVS DR模型中Realserver上的准备

A. [root@steppingstone ~]# rs ' cd /proc/sys/net/ipv4/conf/; pwd'; echop; done
B. [root@steppingstone ~]# rs 'echo 2 > /proc/sys/net/ipv4/conf/all/arp_announce'; echop; done #修改arp_announce
C. [root@steppingstone ~]# rs 'echo 2 > /proc/sys/net/ipv4/conf/eth0/arp_announce'; echop; done
D. [root@steppingstone ~]# rs 'echo 1 > /proc/sys/net/ipv4/conf/eth0/arp_ignore'; echop; done
E. [root@steppingstone ~]# rs ' echo 1 > /proc/sys/net/ipv4/conf/all/arp_ignore'; echop; done
F. [root@steppingstone ~]# rs 'ifconfig lo:0 192.168.205.80 broadcast 192.168.205.80 netmask 255.255.255.255 up; ifconfig lo:0'; echop; done #配置vip地址
H. [root@steppingstone ~]# rs 'yum install httpd; echo "<h1>`uname -n`</h1>"> /var/www/html/index.html; service httpd restart'; echop; done #安装web服务

3. ha上的准备

A. [root@steppingstone ~]# ha 'yum install keepalived -y'; echop; done #安装keepalived
B. [root@steppingstone ~]# ha 'yum install ipvsadm -y'; echop; done #安装ipvsadm

4. 配置keepalived

A. [root@ha2 ~]# man keepalived.conf #查看帮助文档
B. [root@ha1 keepalived]# vim keepalived.conf

 ! Configuration File for keepalived
 
 global_defs {
 notification_email {
 #指定故障发生时通告给的邮件地址
 xxxxx@.com
 }
 #发送者信息
 notification_email_from xxxxxx@.com
 smtp_server smtp..com
 smtp_connect_timeout
 router_id LVS_DEVEL
 }
 vrrp_script chk_schedown {
 #此处可自定义检测脚本, 0表示测试成功,此处以检测是否存在改文件做测试
 script "[ -e /etc/keepalived/down ] && exit 1 || exit 0"
 #每两秒检测一次
 interval
 #如果失败, 优先级减去多少
 weight -
 #失败检测次数,失败2次才是失败
 fall
 #成功一次, 即时成功
 rise
 }
 vrrp_instance VI_1 {
 #定义vrrp虚拟路由
 state MASTER
 #定义工作的物理接口
 interface eth0
 #两台ha上的虚拟路由id要保持一致
 virtual_router_id
 #优先级要比备节点大
 priority
 advert_int
 #定义认证码
 authentication {
 #认证类型为简单字符认证
 auth_type PASS
 auth_pass keepalivedpass
 }
 #定义提供服务的虚拟ip
 virtual_ipaddress {
 192.168.205.80/ dev eth0 label eth0:
 }
 #定义要检查的脚本
 track_script {
 chk_schedown
 }
 #定义keepalived节点转换通知
 notify_master "/etc/keepalived/keepalived_notify.sh master 192.168.205.80"
 notify_backup "/etc/keepalived/keepalived_notify.sh backup 192.168.205.80"
 notify_fault "/etc/keepalived/keepalived_notify.sh fault 192.168.205.80"
 }
 #定义vitual_server
 virtual_server 192.168.205.80  {
 delay_loop
 lb_algo rr
 lb_kind DR
 nat_mask 255.255.255.0
 #指定是否使用长连接
 #persistence_timeout
 protocol TCP
 sorry_server 127.0.0.1
 #指定realserver rs1,
 # HTTP_GET|SSL_GET|TCP_CHECK|SMTP_CHECK|MISC_CHECK, 可分别针对于http, https, mysql, mail等进行健康状况监测
 real_server 192.168.205.112  {
 weight
 HTTP_GET {
 url {
 path /
 #http返回状态为200, 说明状态ok
 status_code
 }
 #定义超时时间
 connect_timeout
 #定义重试次数
 nb_get_retry
 delay_before_retry
 }
 }
 real_server 192.168.205.118  {
 weight
 HTTP_GET {
 url {
 path /
 #http返回状态为200, 说明状态ok
 status_code
 }
 #定义超时时间
 connect_timeout
 #定义重试次数
 nb_get_retry
 delay_before_retry
 }
 }

keepalived.conf

C. [root@ha1 keepalived]# scp keepalived.conf ha2:/etc/keepalived/ #拷贝到另一台设备上

D. [root@ha2 ~]# vim /etc/keepalived/keepalived.conf #修改ha2上的配置

#配置状态
state BACKUP
#优先级
priority 100

E. [root@steppingstone ~]# ha 'service keepalived start'; echop; done #启动服务
F. [root@steppingstone ~]# ha 'ifconfig'; echop; done #查看网卡状态

G. [root@steppingstone ~]# ha 'ipvsadm -L -n'; echop; done #查看ipvs规则

5. 测试Realserver的切换

A. [root@rs1 ~]# service httpd stop #在一台rs上停止web服务
B. [root@steppingstone ~]# ha 'ipvsadm -L -n'; echop; done

C. 通知邮件

6. failback页面测试

A. [root@steppingstone ~]# ha 'yum install httpd -y; echo "<h1>`uname -n`, RealServer is rairing!</h1>">/www/html/index.html; service httpd start'; echop; done
B. 测试

a. [root@steppingstone ~]# rs 'service httpd stop'; echop; done #停掉realserver
b. [root@steppingstone ~]# ha 'ipvsadm -L -n'; echop; done

c. [root@rs1 ~]# service httpd start

d. [root@steppingstone ~]# ha 'ipvsadm -L -n'; echop; done

7. keepalived自动切换

A. [root@ha1 ~]# touch /etc/keepalived/down #创建文件模拟测试

B. [root@ha1 keepalived]# tail /var/log/messages -f | grep Keepalived #查看日志

8. keepalived切换邮件通告

A. [root@ha1 ~]# vim /etc/keepalived/keepalived_notify.sh #编辑邮件通知脚本, 改文件拷贝到ha2上相同位置

#!/bin/bash
 
#指定要接收的邮件的联系人
contact=xxxxxx@163.com
 
#命令帮助函数
Usage() {
echo "Usage: `basename $0` {master|backup|fault} VIP"
}
 
#发送邮件函数
Notify() {
subject="`hostname`s status changed to $1"
mailbody="`date "+%F %T"`: `hostname`'s status change to $1, $VIP floating."
echo $mailbody | mail -s "$subject" -r xxxxxx@163.com $contact
}
 
#判断命令使用是否正确
[ $# -lt 2 ] && Usage && exit
#接收到vip地址
VIP=$2
#判断主题
case $1 in
master)
Notify master
;;
backup)
Notify backup
;;
fault)
Notify fault
;;
*)
Usage
exit 1
;;
esac

B. [root@ha1 ~]# vim /etc/keepalived/keepalived.conf #查看配置文件

vrrp_instance VI_1 {
#定义keepalived节点转换通知
notify_master "/etc/keepalived/keepalived_notify.sh master 192.168.205.80"
notify_backup "/etc/keepalived/keepalived_notify.sh backup 192.168.205.80"
notify_fault "/etc/keepalived/keepalived_notify.sh fault 192.168.205.80"
}

C. 通知邮件