LVS+Keepalived实现高可用集群

Linux server部署环境

操作系统平台：CentOS5.4

软件：LVS+keepalived+nginx（apache不做介绍）

一.LVS+Keepalived 介绍
LVS

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。本项目在1998年5月由章文嵩博士成立，是中国国内最早出现的自由软件项目之一。目前有三种IP负载均衡技术（VS/NAT、VS/TUN和VS/DR）；
十种调度算法（rrr|wrr|lc|wlc|lblc|lblcr|dh|sh|sed|nq）。
Keepalvied
Keepalived在这里主要用作RealServer的健康状态检查以及LoadBalance主机和BackUP主机之间failover的实现




二.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

三.安装LVS和Keepalvied软件包
   
1. 下载相关软件包 
#mkdir /usr/local/src/lvs
#cd /usr/local/src/lvs
#wget 
http://www.linuxvirtualserver.org/software/kernel-2.6/ipvsadm-1.24.tar.gz
#wget 
http://www.keepalived.org/software/keepalived-1.1.15.tar.gz

2. 安装LVS和Keepalived 
#lsmod |grep ip_vs
#uname -r
2.6.18-53.el5PAE
#ln -s /usr/src/kernels/2.6.18-53.el5PAE-i686/  /usr/src/linux

#tar zxvf ipvsadm-1.24.tar.gz
#cd ipvsadm-1.24
#make && make install
#find / -name ipvsadm  # 查看ipvsadm的位置

#tar zxvf keepalived-1.1.15.tar.gz
#cd keepalived-1.1.15
#./configure  && make && make install
#find / -name keepalived  # 查看keepalived位置                
    
#cp /usr/local/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/
#cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/
#mkdir /etc/keepalived
#cp /usr/local/etc/keepalived/keepalived.conf /etc/keepalived/
#cp /usr/local/sbin/keepalived /usr/sbin/
#service keepalived start|stop     #做成系统启动服务方便管理.
四. 配置LVS实现负载均衡

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
#Written by :NetSeek 
http://www.linuxtone.org
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
# Written by NetSeek 
# 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

五．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 {
     
[email protected]
     
[email protected]
     
[email protected]
   }
   notification_email_from 
[email protected]
   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 {
     
[email protected]
     
[email protected]
     
[email protected]
   }
   notification_email_from 
[email protected]
   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。
相关参考
1．LVS 基础知识汇总
LVS的算法介绍            
http://www.linuxtone.org/viewthread.php?tid=69
学习LVS的三种转发模式     
http://www.linuxtone.org/viewthread.php?tid=77
LVS中的IP负载均衡技术     
http://www.linuxtone.org/viewthread.php?tid=68
更多的请到
http://www.linuxtone.org   http://www.linuxvirtualserver.org/
负载均衡版查看
Keepalived 相关参考资料。http://www.keepalived.org/documentation.html