LVS+Keepalived实现高可用集群

操作系统平台：CentOS5.2

软件：LVS+keepalived

 

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

 

 

IP配置信息:

1. LVS-DR-Master          192.168.2.166
2. LVS-DR-BACKUP          192.168.2.167
3. LVS-DR-VIP             192.168.2.170       
4. WEB1-Realserver        192.168.2.171
5. WEB2-Realserver        192.168.2.172
6. GateWay                192.168.2.253

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

#wget

 

2. 安装LVS和Keepalived

1. #lsmod |grep ip_vs
   
2. #uname -r
   
3. 2.6.18-53.el5PAE
   
4. #ln -s /usr/src/kernels/2.6.18-53.el5PAE-i686/  /usr/src/linux
   
5. 
   
6. #tar zxvf ipvsadm-1.24.tar.gz
   
7. #cd ipvsadm-1.24
   
8. #make && make install
   
9. #find / -name ipvsadm  # 查看ipvsadm的位置
   
10. 
    
11. #tar zxvf keepalived-1.1.15.tar.gz
    
12. #cd keepalived-1.1.15
    
13. #./configure  && make && make install
    
14. #find / -name keepalived  # 查看keepalived位置               
    
15.    
    
16. #cp /usr/local/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/
    
17. #cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/
    
18. #mkdir /etc/keepalived
    
19. #cp /usr/local/etc/keepalived/keepalived.conf /etc/keepalived/
    
20. #cp /usr/local/sbin/keepalived /usr/sbin/
    
21. #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
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 {
    
    
    
   }
   notification_email_from
   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 {
    
    
    
   }
   notification_email_from
   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。


四．相关参考

1．LVS 基础知识汇总

LVS的算法介绍            php?tid=69
学习LVS的三种转发模式    
LVS中的IP负载均衡技术    

更多的请到 负载均衡版查看

Keepalived 相关参考资料。
   http://www.keepalived.org/documentation.html