最近用HAproxy+keepalived+mysql复制测试高可用性Linux系统集群。
  HAProxy是一款免费的提供高可用性、负载均衡以及基于TCP（第四层）和HTTP（第七层）应用的代理软件，借助HAProxy可以快速并且可靠的提供基于TCP和HTTP应用的代理解决方案。
  Keepalived主要作用是LoadBalance master和LoadBalance backup之间的健康检查，实现故障转换。
  Mysql Replication主要作用是提高mysql并处理数据的能力以及实现容灾备份的作用。

项目拓扑图：

Haproxy服务器及其IP地址规划：

项目实施：

1.Mysql主从复制配置。

1)在master服务器上创建mysql用户（授权复制账户）。
grant replication slave on *.* to'rep'@'192.168.1.244'identified by 'rep123';
2)编辑master服务器的mysql配置文件my.cnf。
server-id= 1 //指定服务器的ID
log-bin = mysql-bin //开启二进制日志
binlog-ignore = mysql //忽略mysql和information_schema 数据库
binlog-ignore = information_schema
binlog-do-db = blog    //同步数据库，默认同步所有数据库
3)查看master状态。
mysql> show master status;
+---------------+----------+--------------+--------------------------+
| File          | Position | Binlog_Do_DB | Binlog_Ignore_DB         |
+---------------+----------+--------------+--------------------------+
| binlog.022343 |   339244 | blog         | mysql,information_schema |
+---------------+----------+--------------+--------------------------+
1 row inset(0.00 sec)
4)在slave端创建数据库blog,导出master端的blog库，导入到此库，并修改mysql主配置文件my.cnf server-id= 2 重启mysql数据库。
mysql> change master to
-> master_host='192.168.1.243',
-> master_port=3306,
-> master_user='rep',
-> master_password='rep123',
-> master_log_file='binlog.022343',
-> master_log_pos=339244;
5)mysql主从同步测试，show slave status\G;能看到Slave_IO_Running和Slave_SQL_Running都为YES即可。
mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting formaster to send event
Master_Host: 192.168.1.243
Master_User: rep
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: binlog.022343
Read_Master_Log_Pos: 339110
Relay_Log_File: relaylog.005481
Relay_Log_Pos: 339244
Relay_Master_Log_File: binlog.022343
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB: mysql,test,information_schema
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 339110
Relay_Log_Space: 339244
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: 0
1 row inset(0.00 sec)

2.Haproxy安装及其配置，master和backup安装配置都是完全一样的.

wget http://haproxy.1wt.eu/download/1.4/src/haproxy-1.4.24.tar.gz
tar-zxvf haproxy-1.4.24.tar.gz
cdhaproxy-1.4.24
makeTARGET=linux26 PREFIX=/usr/local/haproxy
makeinstallPREFIX=/usr/local/haproxy
cd/usr/local/haproxy
mkdirconf logs   //在此目录下面建立conf，logs目录分别存放HAproxy的配置文件，PID文件和日志文件。
vim conf/haproxy.conf
global
maxconn 50000
chroot /usr/local/haproxy
uid 99
gid 99
daemon
quiet
nbproc  2
pidfile /usr/local/haproxy/logs/haproxy.pid
#debug
defaults
log     global
mode    http
option  httplog   #每次请求完毕后主动关闭http通道
option  dontlognull #不记录健康检查的日志信息
option forwardfor
option redispatch
option abortonclose
retries 3
log 127.0.0.1 local3
maxconn 20000
contimeout      5000
clitimeout      50000
srvtimeout      50000
listen 192.168.1.236
bind *:80
mode http
stats uri /admin#后端服务器状态查看地址
stats auth admin:admin             #状态查看页面登陆帐号密码
balance source#调度算法，source是和nginx的ip_hash同理，解决session问题
option httpclose
option forwardfor
server web1 192.168.1.248:80 weight 5 check inter 2000 rise 2 fall 5
server web2 192.168.1.249:8080 weight 5 check inter 2000 rise 2 fall 5
#启动Haproxy服务
/usr/local/haproxy/sbin/haproxy-f haproxy.conf
#haproxy启动脚本
#!/bin/bash
BASE_DIR="/usr/local/haproxy"
ARGV="$@"
start()
{
echo"START HAPoxy SERVERS"
$BASE_DIR/sbin/haproxy-f $BASE_DIR/conf/haproxy.conf
}
stop()
{
echo"STOP HAPoxy Listen"
kill-TTOU $(cat$BASE_DIR/logs/haproxy.pid)
echo"STOP HAPoxy process"
kill-USR1 $(cat$BASE_DIR/logs/haproxy.pid)
}
case$ARGV in
start)
start
ERROR=$?
;;
stop)
stop
ERROR=$?
;;
restart)
stop
start
ERROR=$?
;;
*)
echo"hactl.sh [start|restart|stop]"
esac
exit$ERROR

3.Haproxy开启系统日志支持。

vim /etc/syslog.conf
#添加：
local3.*        /var/log/haproxy.log
local0.*        /var/log/haproxy.log
vim /etc/sysconfig/syslog
#修改：
SYSLOGD_OPTIONS="-r -m 0"
#重新启动syslog服务
/etc/init.d/syslogrestart

4.Keepalived的安装配置。

wget http://www.keepalived.org/software/keepalived-1.2.5.tar.gz
ln-s /usr/src/kernels/2.6.18-164.el5-x86_64/ /usr/src/linux
tar-zxvf keepalived-1.2.5.tar.gz
cdkeepalived-1.2.5
./configure--prefix=/usr/local/keepalived
make&& makeinstall
cpkeepalived/etc/init.d/keepalived.rh.init /etc/init.d/keepalived
chmod+x /etc/init.d/keepalived
cpkeepalived/etc/init.d/keepalived.sysconfig /etc/sysconfig/keepalived
chkconfig --add keepalived
chkconfig --level 35 keepalived on
cp/usr/local/keepalived/sbin/keepalived/bin/
mkdir-p /etc/keepalived
cp/usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
#Haproxy master配置文件
vim /etc/keepalived/keepalived.conf
! Configuration File forkeepalived
global_defs {
notification_email {
shifeng_zhang88@163.com
}
notification_email_from shifeng_zhang88@163.com
smtp_server smtp.163.com
smtp_connect_timeout 30
router_id LVS_Master
}
vrrp_script chk_http_port {
script  "/etc/keepalived/check_haproxy.sh"
interval        5       #脚本执行间隔
weight         -5       #执行脚本后优先级变更：5表示优先级+5；-5则表示优先级-5
}
vrrp_instance VI_A {
state MASTER
interface eth0
virtual_router_id 50
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass sfzhang1109
}
track_script {
chk_http_port
}
virtual_ipaddress {
192.168.1.236    #haproxy虚拟IP
}
}
#Haproxy backup配置文件只需改变state和priority的值
state BACKUP
priority 50
#启动keepalived服务
/etc/init.d/keepalivedstart

5.编辑check_haproxy.sh脚本，需要将haproxy启动脚本放到/etc/init.d/里面。

vim /etc/keepalived/check_haproxy.sh
#!/bin/bash
A=`ps-C haproxy --no-header |wc-l`
if[ $A -eq0 ];then
/etc/init.d/haproxyrestart
echo"Start haproxy"&> /dev/null
sleep3
if[ `ps-C haproxy --no-header |wc-l` -eq0 ];then
/etc/init.d/keepalivedstop
echo"Stop keepalived"&> /dev/null
fi
fi
#chomd +x /etc/keepalived/check_haproxy.sh

6.Haproxy+Keepalived高可用性测试。

  测试方法：当后端的WEB服务器down机时，haproxy会自动检测到并把请求发送到正常的服务器上面,通过haproxy监控页面（http://192.168.1.235/admin）可以查看。

   说明：（希望大家提出宝贵的意见）

     1）拓扑图只是项目的一个雏形，后期还要添加监控服务器和邮件等服务器。

     2）Mysql主库负责用户数据的写入，slave负责用户数据的读取和数据的备份等，除了要监控mysql主从外还要监控Seconds_Behind_Master选项，以免产生主从数据不同步或者延时。

     3）当WEB的负载很大的时候，可以在haproxy添加多台物理机即可，并考虑把项目的图片分离出来做成单独的图片服务器。