keepalived双主模式高可用工作于NAT模型下的ipvs
一、Keepalived简介ipvs提供高可用性，能够生成ipvs规则；也可以使用脚本来帮助高可用其他应用程序，没有heartbeart重量级；主要用在高可用ipvs，及一些反向代理应用程序
。
1.拓扑图
http://zerofly.blog.运维网.com//attachment/201409/22/4476065_14114250666ioF.png
说明：1.两个代理服务器通过VIP向外提供数据
2.两个代理服务器都可以代理后端的服务器
3.为测试方便，后端服务器至提供静态页面
2.ip规划
http://zerofly.blog.运维网.com//attachment/201409/22/4476065_141142506712rK.png
3.安装配置haproxy
关于haproxy的详细配置，
[*]
[*]# cat /etc/haproxy/haproxy.cfg
[*]#---------------------------------------------------------------------
[*]# Example configuration for a possible web application.See the
[*]# full configuration options online.
[*]#
[*]# http://haproxy.1wt.eu/download/1.4/doc/configuration.txt
[*]#
[*]#---------------------------------------------------------------------
[*]#---------------------------------------------------------------------
[*]# Global settings
[*]#---------------------------------------------------------------------
[*]global
[*]# to have these messages end up in /var/log/haproxy.log you will
[*]# need to:
[*]#
[*]# 1) configure syslog to accept network log events.This is done
[*]# by adding the '-r' option to the SYSLOGD_OPTIONS in
[*]# /etc/sysconfig/syslog
[*]#
[*]# 2) configure local2 events to go to the /var/log/haproxy.log
[*]# file. A line like the following can be added to
[*]# /etc/sysconfig/syslog
[*]#
[*]# local2.* /var/log/haproxy.log
[*]#
[*]log 127.0.0.1 local2
[*]chroot /var/lib/haproxy
[*]pidfile /var/run/haproxy.pid
[*]maxconn 4000
[*]user haproxy
[*]group haproxy
[*]daemon
[*]# turn on stats unix socket
[*]stats socket /var/lib/haproxy/stats
[*]#---------------------------------------------------------------------
[*]# common defaults that all the 'listen' and 'backend' sections will
[*]# use if not designated in their block
[*]#---------------------------------------------------------------------
[*]defaults
[*]mode http
[*]log global
[*]option httplog
[*]option dontlognull
[*]option http-server-close
[*]option forwardfor except 127.0.0.0/8
[*]option redispatch
[*]retries 3
[*]timeout http-request 10s
[*]timeout queue 1m
[*]timeout connect 10s
[*]timeout client 1m
[*]timeout server 1m
[*]timeout http-keep-alive 10s
[*]timeout check 10s
[*]maxconn 3000
[*]#---------------------------------------------------------------------
[*]# main frontend which proxys to the backends
[*]#---------------------------------------------------------------------
[*]frontendmain *:80
[*]default_backend static
[*]#---------------------------------------------------------------------
[*]# static backend for serving up images, stylesheets and such
[*]#---------------------------------------------------------------------
[*]backend static
[*]balance roundrobin
[*]server node2 192.168.1.202:80 check maxconn 2000
[*]server node3 192.168.1.203:80 check maxconn 2000
[*]#---------------------------------------------------------------------
[*]# round robin balancing between the various backends
[*]#---------------------------------------------------------------------
说明：两个节点的HAproxy的配置文件应该保持一样
4.测试haproxy的配置
http://zerofly.blog.运维网.com//attachment/201409/22/4476065_1411425067a9VF.png
http://zerofly.blog.运维网.com//attachment/201409/22/4476065_1411425067PjGp.png
5.安装配置keepalived
①、安装keepalived
keepalived的安装可以通过yum源来安装，也可以通过编译源码来安装，本处通过yum源赖安装
②、配置keepalived主节点
[*]# cat /etc/keepalived/keepalived.conf
[*]! Configuration File for keepalived
[*]global_defs {//全局参数
[*]notification_email { //邮件
[*]sysadmin@firewall.loc //收件人地址
[*]}
[*]notification_email_from Alexandre.Cassen@firewall.loc //发件人地址
[*]smtp_server 127.0.0.1 //邮件服务器的地址
[*]smtp_connect_timeout 30 //间隔时间
[*]router_id LVS_DEVEL//邮件服务器的组的id
[*]}
[*]vrrp_script chk_haproxy {
[*]script "killall -0 haproxy" //检查haproxy是否在线
[*]interval 1 //检查间隔时间
[*]weight -5 //如果检查失败，则权重-5
[*]}
[*]vrrp_instance VI_1 { //定义第一个集群
[*]state MASTER //初始状态为主节点，从节点应该为BACKUP
[*]interface eth0 //配置ip的端口
[*]virtual_router_id 51 //本组集群的id号，主从节点必须一样
[*]priority 100 //主节点的优先级，备用节点的优先级必须低于主节点
[*]advert_int 1 //心跳检查间隔时间
[*]authentication {
[*]auth_type PASS //通信为明文密码通信
[*]auth_pass 1111 //通信的密码，主从节点必须一样
[*]}
[*]virtual_ipaddress {
[*]192.168.1.99 //定义一个VIP
[*]}
[*]track_script { //调用上面的命令
[*]chk_haproxy
[*]}
[*]}
③、配置keepalived从节点
[*]# cat /etc/keepalived/keepalived.conf
[*]! Configuration File for keepalived
[*]global_defs {
[*]notification_email {
[*]sysadmin@firewall.loc
[*]}
[*]notification_email_from Alexandre.Cassen@firewall.loc
[*]smtp_server 127.0.0.1
[*]smtp_connect_timeout 30
[*]router_id LVS_DEVEL
[*]}
[*]vrrp_script chk_haproxy {
[*]script "killall -0 haproxy"
[*]interval 1
[*]weight -5
[*]}
[*]vrrp_instance VI_1 {
[*]state BACKUP
[*]interface eth0
[*]virtual_router_id 51
[*]priority 99
[*]advert_int 1
[*]authentication {
[*]auth_type PASS
[*]auth_pass 1111
[*]}
[*]virtual_ipaddress {
[*]192.168.1.99
[*]}
[*]track_script {
[*]chk_haproxy
[*]}
[*]}
[*]2: eth0:mtu 1500 qdisc pfifo_fast state UP qlen 1000
[*]link/ether 00:0c:29:56:78:cd brd ff:ff:ff:ff:ff:ff
[*]inet 192.168.1.204/24 brd 192.168.1.255 scope global eth0
[*]inet 192.168.1.99/32 scope global eth0
[*]inet6 fe80::20c:29ff:fe56:78cd/64 scope link tentative dadfailed
[*]valid_lft forever preferred_lft forever
可以看到ip地址已经配置上去了
http://zerofly.blog.运维网.com//attachment/201409/22/4476065_14114250689uBJ.png
我们可以看到网页访问正常
下面，我们模拟服务器损坏，将node1上的haproxy关掉，看看ip地址是否会转移到node4上
[*]# ip add
[*]1: lo:mtu 16436 qdisc noqueue state UNKNOWN
[*]link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
[*]inet 127.0.0.1/8 scope host lo
[*]inet6 ::1/128 scope host
[*]valid_lft forever preferred_lft forever
[*]2: eth0:mtu 1500 qdisc pfifo_fast state UP qlen 1000
[*]link/ether 00:0c:29:56:78:cd brd ff:ff:ff:ff:ff:ff
[*]inet 192.168.1.204/24 brd 192.168.1.255 scope global eth0
[*]inet 192.168.1.99/32 scope global eth0
[*]inet6 fe80::20c:29ff:fe56:78cd/64 scope link tentative dadfailed
[*]valid_lft forever preferred_lft forever
http://zerofly.blog.运维网.com//attachment/201409/22/4476065_1411425067a9VF.png
查看网页是否能够访问正常
OK！！可以看到我们的页面访问正常，这就可以实现当前段的一个反向代理服务器宕机或者后端的一个web服务宕机，服务都可以正常对外提供
7.扩展
我们还可以自定义通知机制
[*]#!/bin/bash
[*]# Author: zero
[*]# description: An example of notify script
[*]#
[*]vip=192.168.1.99
[*]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
[*]exit 0
[*];;
[*]backup)
[*]notify backup
[*]exit 0
[*];;
[*]fault)
[*]notify fault
[*]exit 0
[*];;
[*]*)
[*]echo 'Usage: `basename $0` {master|backup|fault}'
[*]exit 1
[*];;
[*]esac
在keepalived的配置文件中通过notify来调用，如下所示
[*]notify_master "/etc/keepalived/notify.sh master"
[*]notify_backup "/etc/keepalived/notify.sh backup"
[*]notify_fault "/etc/keepalived/notify.sh fault"
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