这里有两台HAProxy机器，分别安装keepalived，组成热备形式。作用：当一台有问题，另一台可以在1秒内接管。

xinetd服务的作用是检测端口，本文中使用8890端口。HAProxy用http协议检测这个端口是否正常。

MySQL同步状态脚本，是放在从库本地，由xinetd服务来激活脚本，正常就会输出200状态码给HAProxy，证明从库正常；否则，就剔除。（这里就可以加上短信报警了）

系统架构图

使用软件

• HAProxy 1.4.16
• Keepalived 1.1.20
• Xinetd 2.3.14
• MySQL 同步状态脚本 0.2

一、系统约定

系统环境

• OS:CentOS 5.6 x86_64
• MASTER:192.168.1.65
• BACKUP:192.168.1.66
• VIP:192.168.1.67
• serivce Port:3306

工作流程

准备工作：应用配置好slave的VIP 192.168.1.67 端口3306

(1)应用服务器

(2)连接HAProxy的vip 192.168.1.67:3306，根据算法，分配到一台slave。

(3)检测slave的8890端口是否返回http 200状态码。

(4)返回200 状态码，HAProxy 返回正常，继续服务。

(5)返回503，剔除该slave，并将mysql请求转发到另外一台slave。

(6)有问题的slave，发送短信报警，相关人员检查。

二、Keepalived 1.1.20的安装于配置

#cd /var/tmp/#wget http://www.keepalived.org/software/keepalived-1.1.20.tar.gz#tar zxvf keepalived-1.1.20.tar.gz#cd keepalived-1.1.20#./configure –prefix=/usr#make && make install#cp /usr/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/#cp /usr/etc/sysconfig/keepalived /etc/sysconfig/#mkdir /etc/keepalivedvim /etc/keepalived/keepalived.conf! Configuration File for keepalivedglobal_defs {   notification_email {    coralzd@gmail.com   }   notification_email_from coralzd@gmail.com   smtp_server 192.168.1.1   smtp_connect_timeout 30   router_id LVS_DEVEL}vrrp_script chk_HAProxy {       script "killall -0 HAProxy"      interval 2       weight 2   }vrrp_instance VI_1 {    state MASTER    interface eth0    virtual_router_id 50    priority 150    advert_int 1    authentication {        auth_type PASS        auth_pass 1111    }    track_interface {          eth0                 }     virtual_ipaddress {        192.168.1.67            }    track_script {           chk_HAProxy       }  }

三、HAProxy 1.4.16的安装与配置

#cd /var/tmp/#wget http://HAProxy.1wt.eu/download/1.4/src/HAProxy-1.4.16.tar.gz#tar -zxvf HAProxy-1.4.16.tar.gz#cd HAProxy-1.4.16#make install#mkdir -p /usr/local/HAProxy/etc#mkdir -p /usr/local/HAProxy/sbin#cp examples/HAProxy.cfg /usr/local/HAProxy/etc#ln -s /usr/local/sbin/HAProxy /usr/local/HAProxy/sbin/HAProxy#mkdir /usr/share/HAProxy/etc/HAProxy/HAProxy.cfgglobal        log 127.0.0.1   local1 notice        maxconn 4096        chroot /usr/share/HAProxy        uid 99        gid 99        daemon        #debug        #quietdefaults        log     global        mode    http        #option httplog        option  dontlognull        retries 3        option  redispatch        maxconn 2000        contimeout      5000        clitimeout      50000        srvtimeout      50000listen  DZW_MYSQL_SLAVE  192.168.1.67:3306        #cookie SERVERID rewrite        mode tcp         maxconn 200        balance roundrobin        option httpchk OPTIONS * HTTP/1.1\r\nHost:\ www         server  mysql_192_168_1_23 192.168.1.23:3306  check port 8890 inter 5s rise 2 fall 3        server  mysql_192_168_1_24 192.168.1.24:3306  check port 8890 inter 5s rise 2 fall 3              srvtimeout      20000  listen  admin_status        mode  http        bind 192.168.1.65:8899        option httplog        log global        stats enable        stats refresh 10s        stats hide-version        stats realm Haproxy\ Statistics        stats uri  /admin-status         stats auth  admin:123456         stats admin if TRUE

HAProxy 启动脚本

/etc/init.d/HAProxy#!/bin/sh## chkconfig: - 85 15# description: HA-Proxy is a TCP/HTTP reverse proxy which is particularly suited \#              for high availability environments.# processname: HAProxy# config: /etc/HAProxy/HAProxy.cfg# pidfile: /var/run/HAProxy.pid# Script Author: Simon Matter <simon.matter@invoca.ch># Version: 2004060600# Source function library.if [ -f /etc/init.d/functions ]; then  . /etc/init.d/functionselif [ -f /etc/rc.d/init.d/functions ] ; then  . /etc/rc.d/init.d/functionselse  exit 0fi# Source networking configuration.. /etc/sysconfig/network# Check that networking is up.[ ${NETWORKING} = "no" ] && exit 0# This is our service nameBASENAME=HAProxyif [ -L ___FCKpd___2 ]; then  BASENAME=`find ___FCKpd___2 -name $BASENAME -printf %l`  BASENAME=`basename $BASENAME`fi[ -f /etc/$BASENAME/$BASENAME.cfg ] || exit 1RETVAL=0start() {  /usr/sbin/$BASENAME -c -q -f /etc/$BASENAME/$BASENAME.cfg  if [ $? -ne 0 ]; then    echo "Errors found in configuration file, check it with '$BASENAME check'."    return 1  fi  echo -n "Starting $BASENAME: "  daemon /usr/sbin/$BASENAME -D -f /etc/$BASENAME/$BASENAME.cfg -p /var/run/$BASENAME.pid  RETVAL=$?  echo  [ $RETVAL -eq 0 ] && touch /var/lock/subsys/$BASENAME  return $RETVAL}stop() {  echo -n "Shutting down $BASENAME: "  killproc $BASENAME -USR1  RETVAL=$?  echo  [ $RETVAL -eq 0 ] && rm -f /var/lock/subsys/$BASENAME  [ $RETVAL -eq 0 ] && rm -f /var/run/$BASENAME.pid  return $RETVAL}restart() {  /usr/sbin/$BASENAME -c -q -f /etc/$BASENAME/$BASENAME.cfg  if [ $? -ne 0 ]; then    echo "Errors found in configuration file, check it with '$BASENAME check'."    return 1  fi  stop  start}reload() {  /usr/sbin/$BASENAME -c -q -f /etc/$BASENAME/$BASENAME.cfg  if [ $? -ne 0 ]; then    echo "Errors found in configuration file, check it with '$BASENAME check'."    return 1  fi  /usr/sbin/$BASENAME -D -f /etc/$BASENAME/$BASENAME.cfg -p /var/run/$BASENAME.pid -sf $(cat /var/run/$BASENAME.pid)}check() {  /usr/sbin/$BASENAME -c -q -V -f /etc/$BASENAME/$BASENAME.cfg}rhstatus() {  status $BASENAME}condrestart() {  [ -e /var/lock/subsys/$BASENAME ] && restart || :}# See how we were called.case "$1" in  start)    start    ;;  stop)    stop    ;;  restart)    restart    ;;  reload)    reload    ;;  condrestart)    condrestart    ;;  status)    rhstatus    ;;  check)    check    ;;  *)    echo ___FCKpd___2quot;Usage: $BASENAME {start|stop|restart|reload|condrestart|status|check}"    exit 1esac exit $?chkconfig –add HAProxy chkconfig HAProxy onservice HAProxy start

四、xinetd安装和配置

yum install -y xinetdvim /etc/xinetd.d/mysql_status.shservice mysqlrep_status{         flags           = REUSE         socket_type     = stream         port            = 8890        wait            = no         user            = nobody         server          = /usr/local/bin/mysqlrep_status.sh        log_on_failure  += USERID         disable         = no         }

重启xinetd

service xinetd restart

MySQL同步检测脚本（脚本检测同步sql和IO进程是否都为真，以及select是否达到20个进程以上）

#!/bin/bash # # /usr/local/bin/mysqlchk_status.sh # # This script checks if a mysql server is healthy running on localhost. It will # return: # # "HTTP/1.x 200 OK\r" (if mysql is running smoothly) # # – OR – # # "HTTP/1.x 503 Internal Server Error\r" (else) # MYSQL_HOST="localhost"MYSQL_PORT="3306"MYSQL_USERNAME="repdb63"MYSQL_PASSWORD="mylqs9eyex7s"# # We perform a simple query that should return a few results #/usr/local/mysql/bin/mysql  -hlocalhost –urepdb63 –pmylqs9eyex7s -e "show slave status\G;"   > /tmp/rep.txtmysql -urepdb63 -pmylqs9eyex7s -e "show full processlist;" >/tmp/processlist.txtmysql -urepdb63 -pmylqs9eyex7s -e "show slave status\G;" >/tmp/rep.txtiostat=`grep "Slave_IO_Running" /tmp/rep.txt  |awk '{print $2}'`            sqlstat=`grep "Slave_SQL_Running" /tmp/rep.txt |awk '{print $2}'`           result=$(cat /tmp/processlist.txt|wc -l)#echo iostat:$iostat and sqlstat:$sqlstat # if slave_IO_Running and Slave_sql_Running ok,then return 200 code if [ "$result" -lt "20" ] && [ "$iostat" = "Yes" ] && [ "$sqlstat" = "Yes" ];then        # mysql is fine, return http 200         /bin/echo -e "HTTP/1.1 200 OK\r\n"         else        # mysql is down, return http 503         /bin/echo -e "HTTP/1.1 503 Service Unavailable\r\n"         fi

注意：在mysql slave另行建立一个具有process和slave_client权限的账号。

作者简介：崔晓辉，网名coralzd，大众网系统管理员，精通网站系统架构、Unix技术。gtalk：coralzd@gmail.com