LVS+Keepalived 实现集群负载均衡

IP配置信息:
LVS-DR-Master          192.168.2.166
LVS-DR-BACKUP          192.168.2.167
LVS-DR-VIP             192.168.2.170       
WEB1-Realserver        192.168.2.171
WEB2-Realserver        192.168.2.172
GateWay                192.168.2.253

一.keepalived安装
Keepalived在这里主要用作RealServer的健康状态检查以及LoadBalance MASTER主机和BACKUP主机之间failover的实现。

参考CentOS 6.3 安装 Keepalived
http://maosheng.iteye.com/blog/2238747

参考Keepalived+Nginx 实现双机热备
http://maosheng.iteye.com/blog/2242594


二.配置LVS实现负载均衡

LVS是Linux Virtual Server的简写，意即Linux虚拟服务器，是一个虚拟的服务器集群系统

1．LVS-DR，配置LVS脚本实现负载均衡

vi /usr/local/sbin/lvs-dr.sh

#!/bin/bash
# description: start LVS of DirectorServer
#

GW=192.168.2.253

# website director vip.
WEB_VIP=192.168.2.170
WEB_RIP1=192.168.2.171
WEB_RIP2=192.168.2.172

. /etc/rc.d/init.d/functions

logger $0 called with $1

case "$1" in

start)
       # Clear all iptables rules.
       /sbin/iptables -F
       # Reset iptables counters.
       /sbin/iptables -Z
       # Clear all ipvsadm rules/services.
       /sbin/ipvsadm -C

#set lvs vip for dr
       /sbin/ipvsadm --set 30 5 60
       /sbin/ifconfig eth0:0 $WEB_VIP broadcast $WEB_VIP netmask 255.255.255.255 up
       /sbin/route add -host $WEB_VIP dev eth0:0
       /sbin/ipvsadm -A -t $WEB_VIP:80 -s wrr -p 3
       /sbin/ipvsadm -a -t $WEB_VIP:80 -r $WEB_RIP1:80 -g -w 1
       /sbin/ipvsadm -a -t $WEB_VIP:80 -r $WEB_RIP2:80 -g -w 1
       touch /var/lock/subsys/ipvsadm >/dev/null 2>&1

       # set Arp
       /sbin/arping -I eth0 -c 5 -s $WEB_VIP $GW >/dev/null 2>&1
      ;;
stop)
       /sbin/ipvsadm -C
       /sbin/ipvsadm -Z
       ifconfig eth0:0 down
       route del $WEB_VIP  >/dev/null 2>&1
       rm -rf /var/lock/subsys/ipvsadm >/dev/null 2>&1
       /sbin/arping -I eth0 -c 5 -s $WEB_VIP $GW
       echo "ipvsadm stoped"
      ;;

status)

       if [ ! -e /var/lock/subsys/ipvsadm ];then
               echo "ipvsadm is stoped"
               exit 1
       else
               ipvsadm -ln
               echo "..........ipvsadm is OK."
       fi
     ;;

*)
       echo "Usage: $0 {start|stop|status}"
       exit 1
esac

exit 0


2．配置Realserver脚本.

#!/bin/bash
# 
# description: Config realserver lo and apply noarp

WEB_VIP=192.168.2.170

. /etc/rc.d/init.d/functions

case "$1" in
start)
      ifconfig lo:0 $WEB_VIP netmask 255.255.255.255 broadcast $WEB_VIP
      /sbin/route add -host $WEB_VIP dev lo:0
      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
      sysctl -p >/dev/null 2>&1
      echo "RealServer Start OK"

      ;;
stop)
      ifconfig lo:0 down
      route del $WEB_VIP >/dev/null 2>&1
      echo "0" >/proc/sys/net/ipv4/conf/lo/arp_ignore
      echo "0" >/proc/sys/net/ipv4/conf/lo/arp_announce
      echo "0" >/proc/sys/net/ipv4/conf/all/arp_ignore
      echo "0" >/proc/sys/net/ipv4/conf/all/arp_announce
      echo "RealServer Stoped"
      ;;
status)
       # Status of LVS-DR real server.
       islothere=`/sbin/ifconfig lo:0 | grep $WEB_VIP`
       isrothere=`netstat -rn | grep "lo:0" | grep $web_VIP`
       if [ ! "$islothere" -o ! "isrothere" ];then
           # Either the route or the lo:0 device
           # not found.
           echo "LVS-DR real server Stopped."
       else
           echo "LVS-DR Running."
       fi
;;
*)
       # Invalid entry.
       echo "$0: Usage: $0 {start|status|stop}"
       exit 1
;;
esac
exit 0

附上realserver机上的/etc/sysctl.conf：

# Kernel sysctl configuration file for Red Hat Linux
#
# For binary values, 0 is disabled, 1 is enabled.  See sysctl(8) and
# sysctl.conf(5) for more details.
# Controls IP packet forwarding
net.ipv4.ip_forward = 1
# Controls source route verification
net.ipv4.conf.default.rp_filter = 1
# Do not accept source routing
net.ipv4.conf.default.accept_source_route = 0
# Controls the System Request debugging functionality of the kernel
kernel.sysrq = 0
# Controls whether core dumps will append the PID to the core filename.
# Useful for debugging multi-threaded applications.
kernel.core_uses_pid = 1
net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.lo.arp_announce = 2
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
或者采用secondary ip address方式配置
# vi /etc/sysctl.conf

添加以下内容如上所示：

net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.lo.arp_announce = 2
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
#sysctl –p
#ip addr add 61.164.122.8/32 dev lo
#ip add list 查看是否绑定

3. 启动lvs-dr脚本和realserver启本，在DR上可以查看LVS当前状态:

#watch ipvsadm –ln

三.利用Keepalvied实现负载均衡和和高可用性

1.配置在主负载均衡服务器上配置keepalived.conf

#vi /etc/keepalived/keepalived.conf (主调度器)
! Configuration File for keepalived
global_defs {
  notification_email {

[e-mail]

[e-mail]

[e-mail]
  }
  notification_email_from
[e-mail]
  smtp_server 127.0.0.1
  smtp_connect_timeout 30
  router_id LVS_DEVEL
}
vrrp_instance VI_1 {
   state MASTER
   interface eth0
   virtual_router_id 51
   priority 100
   advert_int 1
   authentication {
       auth_type PASS
       auth_pass 1111
   }
   virtual_ipaddress {
       192.168.2.170
   }
}
virtual_server 192.168.2.170 80 {
   delay_loop 6
   lb_algo wrr
   lb_kind DR
   persistence_timeout 60
   protocol TCP

   real_server 192.168.2.171 80 {
       weight 3            
       TCP_CHECK {
       connect_timeout 10  
       nb_get_retry 3
       delay_before_retry 3
       connect_port 80
}
   }
   real_server 192.168.2.172 80 {
       weight 3
       TCP_CHECK {
       connect_timeout 10
       nb_get_retry 3
       delay_before_retry 3
       connect_port 80
       }
    }
}

在备用调度器上：

#vi /etc/keepalived/keepalived.conf (备用调度器)
! Configuration File for keepalived
global_defs {
  notification_email {

[e-mail]

[e-mail]

[e-mail]
  }
  notification_email_from
[e-mail]
  smtp_server 127.0.0.1
  smtp_connect_timeout 30
  router_id LVS_DEVEL
}
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 {
       192.168.2.170
   }
}
virtual_server 192.168.2.170 80 {
   delay_loop 6
   lb_algo wrr
   lb_kind DR
   persistence_timeout 60
   protocol TCP

   real_server 192.168.2.171 80 {
       weight 3            
       TCP_CHECK {
       connect_timeout 10  
       nb_get_retry 3
       delay_before_retry 3
       connect_port 80
}
   }
   real_server 192.168.2.172 80 {
       weight 3
       TCP_CHECK {
       connect_timeout 10
       nb_get_retry 3
       delay_before_retry 3
       connect_port 80
       }
    }
}

2. BACKUP服务器同上配置，先安装lvs再按装keepalived,仍后配置/etc/keepalived/keepalived.conf，只需将红色标示的部分改一下即可.

3. vi /etc/rc.local
  #/usr/local/sbin/lvs-dr.sh      将lvs-dr.sh这个脚本注释掉。
  #/usr/local/sbin/lvs-dr.sh stop 停止lvs-dr脚本
  #/etc/init.d/keepalived start  启动keepalived 服务，keepalived就能利用keepalived.conf 配置文件，实现负载均衡和高可用.

4. 查看lvs服务是否正常

#watch ipvsadm –ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddressort Scheduler Flags
-> RemoteAddressort           Forward Weight ActiveConn InActConn
TCP  61.164.122.8:80 wrr persistent 60
-> 61.164.122.10:80            Route   3      0          0
-> 61.164.122.9:80             Route   3      0          0
复制代码
#tail –f /var/log/message  监听日志，查看状态，测试LVS负载均衡及高可用性是否有效。

5．停Master服务器的keepalived服务，查看BAKCUP服务器是否能正常接管服务。