在Linux 下 用HAProxy给MySQL做负载均衡

写在前面：由于mysql master 主机上的xinet传给Haproxy的状态不稳定，haproxy会不停的切换mysql主机，造成网站应用反应慢，建议做mysql主从服务器者谨用（用mysql-proxy读写分离代替），mysql cluster方案可以用。

1. 添加监控MySQL状态的端口

在db服务器上(每台都一样)

安装xinetd 
# yum install xinetd
# vi /etc/services

================================================

mysqlcheck      6033/tcp                        # MySQL status check

2. 使用xinetd守护进程运行MySQL状态检测

在db服务器上
# cat /etc/xinetd.d/mysqlchk

=================================================

service mysqlcheck
{
        disable         = no
        flags           = REUSE
        socket_type     = stream
        port            = 6033
        wait            = no
        user            = root
        server          = /usr/local/haproxy/sbin/mysqlchk_status.sh
        log_on_failure  += USERID

        only_from       = 192.168.3.0/24 # recommended to put the IPs that need
                                    # to connect exclusively (security purposes)

}

3. 状态检测脚本

在db服务器上
# vi /usr/local/haproxy/sbin/mysqlchk_status.sh

================================================

 #/bin/bash
MYSQL_HOST="localhost"
MYSQL_PORT="3306"
MYSQL_USERNAME="root"
MYSQL_PASSWORD="123456"
 
#ERROR_MSG=/usr/bin/mysql --host=$MYSQL_HOST --port=$MYSQL_PORT --user=$MYSQL_USERNAME --password=$MYSQL_PASSWORD -e "show databases;"
 
ERROR_MSG=`ps -e | grep mysqld |wc -l`

 

if [ "$ERROR_MSG" != "0" ]
then
        # mysql is fine, return http 200
        /bin/echo -e "HTTP/1.1 200 OK\r\n"
        /bin/echo -e "Content-Type: Content-Type: text/plain\r\n"
        /bin/echo -e "\r\n"
        /bin/echo -e "MySQL is running.\r\n"
        /bin/echo -e "\r\n"
else
        # mysql is fine, return http 503
        /bin/echo -e "HTTP/1.1 503 Service Unavailable\r\n"
        /bin/echo -e "Content-Type: Content-Type: text/plain\r\n"
        /bin/echo -e "\r\n"
        /bin/echo -e "MySQL is *down*.\r\n"
        /bin/echo -e "\r\n"
fi

 ==================================================================

# chmod +x  /usr/local/haproxy/sbin/mysqlchk_status.sh

# service xinetd stop

# service xinetd start

# chown haproxy.haproxy /usr/local/haproxy/sbin/mysqlchk_status.sh

4. HAproxy日志
# touch /var/log/haproxy.log
# chown haproxy.haproxy /var/log/haproxy.log
编辑/etc/syslog.conf文件，添加如下语句

local0.*                                                /var/log/haproxy.log

5. HAProxy配置文件

在均衡服务器上
[root@localhost htdocs]# cat /usr/local/haproxy/conf/haproxy.conf

================================================================

global
        maxconn 4096
        daemon
        pidfile /usr/local/haproxy/run/haproxy.pid
        #debug
        #quiet
        user haproxy
        group haproxy
 
defaults
        log     global
        mode    http
        option  httplog
        option  dontlognull
        log 127.0.0.1 local0
        retries 3
        option redispatch
        maxconn 2000
        contimeout      5000
        clitimeout      50000 #如果程序执行时间很长，把这个值调大一些 我在后面多加两个0改成5000000 毫秒
        srvtimeout      50000
 
listen  admin_stats 192.168.0.1:80
        mode        http
        stats uri   /dbs
        stats realm     Global\ statistics
        stats auth  test:123456
 
listen  proxy-mysql 0.0.0.0:23306
        mode tcp
        balance roundrobin
        option httpchk OPTIONS * HTTP/1.1\r\nHost:\ www
        server db01 192.168.0.1:3306 weight 1 check port 6033 inter 1s rise 2 fall 2
        server db02 192.168.0.2:3306 weight 1 check port 6033 inter 1s rise 2 fall 2
        option tcpka

===================================================

6. HAProxy启动脚本

在均衡服务器上
# cat /etc/init.d/haproxy

===================================================

 #! /bin/sh
set -e
 
PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/haproxy/sbin
PROGDIR=/usr/local/haproxy
PROGNAME=haproxy
DAEMON=$PROGDIR/sbin/$PROGNAME
CONFIG=$PROGDIR/conf/$PROGNAME.conf
PIDFILE=$PROGDIR/run/$PROGNAME.pid
DESC="HAProxy daemon"
SCRIPTNAME=/etc/init.d/$PROGNAME
 
# Gracefully exit if the package has been removed.
test -x $DAEMON || exit 0
 
start()
{
        echo -n "Starting $DESC: $PROGNAME"
        $DAEMON -f $CONFIG
        echo "."
}
 
stop()
{
        echo -n "Stopping $DESC: $PROGNAME"
        haproxy_pid=cat $PIDFILE
        kill $haproxy_pid
        echo "."
}
 
restart()
{
        echo -n "Restarting $DESC: $PROGNAME"
        $DAEMON -f $CONFIG -p $PIDFILE -sf $(cat $PIDFILE)
        echo "."
}
 
case "$1" in
  start)
        start
        ;;
  stop)
        stop
        ;;
  restart)
        restart
        ;;
  *)
        echo "Usage: $SCRIPTNAME {start|stop|restart}" >&2
        exit 1
        ;;
esac
 
exit 0