基于keepalived构建HA集群

一、keepalived简介

1.Keepalived的作用是检测RealServer的健康状态，如果有一台RealServer服务器宕机，Keepalived将检测到，并将宕掉的RealServer服务器从系统中剔除，当RealServer服务器重新恢复正常工作后Keepalived自动将RealServer服务器加入到服务器群中。

2.keeepalived常见模型

<1>主从模型：（主节点修复后服务返回主节点）

定义一个VIP（定义在网卡别名之上）

在vrrp_instance做如下修改：

stateMASTER#从节点为BACKUP

priority101#指定优先级，数字越大优先级越高，主节点的优先级高于从节点

<2>双主模型：

创建两个虚拟路由器，两个节点互为主从

指定两个vrrp_instance互为主从

virtual_router_id不相同

<3>LVS+keepalived

首先配置LVS

配置keepalived，添加虚拟服务，指定lvs模型及调度算法

实战篇

系统环境：centos6.4-i386

yum-yinstallkeepalived

keepalivedi686-1.2.7-3

二、主从模型HA集群

修改主配置文件：vim/etc/keepalived/keepalived.conf

! Configuration File for keepalived
global_defs {
notification_email {
[email protected]
[email protected]
}
notification_email_from [email protected]
smtp_connect_timeout 3
smtp_server 127.0.0.1  #邮件发送者为本地主机
router_id LVS_DEVEL
}
vrrp_script chk_haproxy {
script "killall -0 haproxy"
interval 1
weight 2
}
vrrp_script chk_mantaince_down {
script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"
interval 1
weight -2
}
vrrp_instance VI_1 {  #vrrp实例
interface eth0
state MASTER  # 从节点为BACKUP
priority 101  # 指定优先级，数字越大优先级越高
virtual_router_id 51
garp_master_delay 1
authentication {
auth_type PASS
auth_pass password
}
track_interface {
eth1
}
virtual_ipaddress {
172.16.15.114/16 dev eth1 label eth1:0 #指定VIP及网卡别名
}
track_script {
chk_haproxy
chk_mantaince_down
}
notify_master "/etc/keepalived/notify.sh master"
notify_backup "/etc/keepalived/notify.sh backup"
notify_fault "/etc/keepalived/notify.sh fault"
}

notify脚本：

#!/bin/bash
vip=172.16.15.114 #指定vip
contact='root@localhost'
notify() {
mailsubject="`hostname` to be $1: $vip floating"
mailbody="`date '+%F %H:%M:%S'`: vrrp transition, `hostname` changed to be $1"
echo $mailbody | mail -s "$mailsubject" $contact
}
case "$1" in
master)
notify master
/etc/rc.d/init.d/haproxy start
exit 0
;;
backup)
notify backup
/etc/rc.d/init.d/haproxy stop
exit 0
;;
fault)
notify fault
exit 0
;;
*)
echo 'Usage: `basename $0` {master|backup|fault}'
exit 1
;;
esac

以windows作为客户端访问172.16.15.114

关掉主服务：servicekeepalivedstop

三、双主模型

原理：创建两个虚拟路由器，两个节点互为主从。

! Configuration File for keepalived
global_defs {
notification_email {
[email protected]
[email protected]
}
notification_email_from [email protected]
smtp_connect_timeout 3
smtp_server 127.0.0.1
router_id LVS_DEVEL
}
vrrp_script chk_haproxy {
script "killall -0 haproxy"
interval 1
weight 2
}
vrrp_script chk_mantaince_down {
script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"
interval 1
weight 2
}
vrrp_instance VI_1 {  #实例1
interface eth1
state MASTER  # BACKUP for slave routers
priority 101  # 100 for BACKUP
virtual_router_id 51
garp_master_delay 1
authentication {
auth_type PASS
auth_pass password
}
track_interface {
eth1
}
virtual_ipaddress {  #VIP1
172.16.15.115/16 dev eth1 label eth1:1
}
track_script {
chk_haproxy
chk_mantaince_down
}
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2
interface eth1
state BACKUP  # BACKUP for slave routers
priority 100  # 100 for BACKUP
virtual_router_id 52
garp_master_delay 1
authentication {
auth_type PASS
auth_pass password
}
track_interface {
eth1
}
virtual_ipaddress {  #VIP2
172.16.15.116/16 dev eth1 label eth1:2
}
track_script {
chk_haproxy
chk_mantaince_down
}
}

在客户端访问172.16.15.115172.16.15.116

查看IP

四、实现LVS+keepalived（LVS--DR）

1、首先配置LVS负载均衡集群

注：LVS在会后续博文中做详细介绍！！！

添加ipvsadm规则

#yum -y install ipvsadm #安装ipvsadm
#ipvsadm #查看ipvsadm信息及规则
#ipvsadm -A -t 172.16.15.117:80 -s rr  #指定Director（调度器）

注释：A(添加规则)

-t(指定协议为TCP)

172.16.15.117:80(指定VIP及端口)

-srr(指定调度算法为rr)

#添加real_server

#ipvsadm -a -t 172.16.15.117:80 -r 172.16.15.5 -g
#ipvsadm -a -t 172.16.15.117:80 -r 172.16.15.14 -g
#ifconfig lo:0 $WEB_VIP netmask 255.255.255.255 broadcast $WEB_VIP  #配置VIP，只允许本地回环
# /sbin/route add -host $WEB_VIP dev lo:0 #添加本地路由
#echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore
#echo "2" >/proc/sys/net/ipv4/conf/lo/arp_announce
#echo "1" >/proc/sys/net/ipv4/conf/all/arp_ignore
#echo "2" >/proc/sys/net/ipv4/conf/all/arp_announce

注释：在此只添加两个节点

-a：添加服务

-r172.16.15.5：指定服务IP

-g：指定lvs模型（默认DR）

2、配置基于keepalived（主从）高可用集群

! Configuration File for keepalived
global_defs {
notification_email {
[email protected]
[email protected]
}
notification_email_from [email protected]
smtp_connect_timeout 3
smtp_server 127.0.0.1
router_id LVS_DEVEL
}
vrrp_script chk_schedown {
script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"
interval 2
weight -2
}
vrrp_instance VI_1 {
interface eth1
state MASTER
priority 101
virtual_router_id 51
garp_master_delay 1
authentication {
auth_type PASS
auth_pass password
}
track_interface {
eth1
}
virtual_ipaddress {
172.16.15.117/16 #指定VIP,此处的VIP和lvs的VIP相同，因此不指定网卡
}
track_script {
chk_schedown
}
}
virtual_server 172.16.15.117 80 { #指定虚拟服务
delay_loop 6
lb_algo rr
lb_kind DR
persistence_timeout 50
protocol TCP
sorry_server 172.16.15.14 80 #错误页面
real_server 172.16.15.5 80 {  #指定rserver1
weight 1
HTTP_GET {
url {
path /
status_code 200 #状态码
}
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
}
}
real_server 172.16.15.14 80 {  #指定rserver2
weight 1
HTTP_GET {
url {
path /
status_code 200
}
connect_timeout 3 #连接超时时间
nb_get_retry 3 #尝试连接次数
delay_before_retry 3 #每次尝试之前等待的时间
}
}
}

在客户端访问172.16.15.117