LVS+keepalived负载均衡实战

LVS+keepalived负载均衡实战

      http://blog.chinaunix.net/space.php?uid=20639775&do=blog&id=154518

一、为什么要使 用负载均衡技术？
1、系统高可用性
2、  系统可扩展性
3、  负载均衡能力
LVS+keepalived能很好的实现以上的要求，LVS提 供负载均衡，keepalived提供健康检查，故障转移，提高系统的可用性！采用这样的架构以后 很容易对现有系统进行扩展，只要在后端添加或者减少realserver，只要更改lvs的 配置文件，并能实现无缝配置变更！

二、LVS+Keepalived介绍
1、  LVS
LVS是一个开源的软件，可以实现LINUX平台下的简单负载均衡。LVS是Linux Virtual Server的缩写，意思是Linux虚拟服务器。目前有三种IP负 载均衡技术（VS/NAT、VS/TUN和VS/DR）；八种调度算法（rr,wrr,lc,wlc,lblc,lblcr,dh,sh）。
2、  keepalived
Keepalived 是运行在lvs 之上，它的主要功能是实现真实机的故障隔离及负载均衡器间的失败 切换，提高系统的可用性

三、LVS+keepalived负载均衡架构图
 

四、LVS+keepalived的安装和配置
1.         配置环境
              System OS：CentOS release 5.4
              Software：ipvsadm-1.24.tar.gz, keepalived-1.1.19.tar.gz
2.         信息列表
名称
IP
LVS-Master
192.168.1.112
LVS-BACKUP
192.168.1.113
LVS-VIP
192.168.1.115
Realserver1
192.168.1.105
Realserver2
192.168.1.103
Realserver3
192.168.1.104
3.         安装lvs
分别在backup lvs和master lvs上安装
wget http://www.linuxvirtualserver.org/software/kernel-2.6/ipvsadm-1.24.tar.gz
ln -s /usr/src/kernels/2.6.18-164.el5-i686/ /usr/src/linux
tar zxvf ipvsadm-1.24.tar.gz
cd ipvsadm-1.24
make && make install
4.         安装keepalived
分别在backup lvs和master lvs上安装
wget http://www.keepalived.org/software/keepalived-1.1.19.tar.gz
tar zxvf keepalived-1.1.19.tar.gz
cd keepalived-1.1.19
./configure --prefix=/usr/local/keepalived
make
make install
cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/
mkdir /etc/keepalived
5.         配置keepadlived
LVS-Master的配置文件如下
[root@linux5 ~]# cat /etc/keepalived/keepalived.conf
global_defs {
notification_email {
               [email protected]    #email 通知
        }
        notification_email_from [email protected]
        smtp_server 127.0.0.1
        smtp_connect_timeout 30
        router_id LVS1          # 设置lvs的id，在一个网络内应该是唯一的
}
vrrp_sync_group test {           #设置vrrp组
group {
        loadbalance
}
}

vrrp_instance loadbalance {
        state MASTER       #设置lvs的状态，报错MASTER和BACKUP两种，必须大写
        interface eth0     #设置对外服务的接口
        lvs_sync_daemon_inteface eth0   #设置lvs监听的接口
        virtual_router_id 51                     #设置虚拟路由表示
        priority 180            #设置优先级，数值越大，优先级越高
        advert_int 5           #设置同步时间间隔
authentication {                    #设置验证类型和密码
        auth_type PASS
        auth_pass 1111
}
virtual_ipaddress {                #设置lvs vip
        192.168.1.115
}
}

virtual_server 192.168.1.115 80 {
        delay_loop 6          #健康检查时间间隔
        lb_algo rr               #负载均衡调度算法
        lb_kind DR            #负载均衡转发规则
        #persistence_timeout 20  #设置会话保持时间，对bbs等很有用
        protocol TCP                #协议
        real_server 192.168.1.105 80 {
        weight 3                #设置权重
        TCP_CHECK {
        connect_timeout 3
        nb_get_retry 3
        delay_before_retry 3
        connect_port 80
}
}
        real_server 192.168.1.103 80 {
        weight 3
        TCP_CHECK {
        connect_timeout 3
        nb_get_retry 3
        delay_before_retry 3
        connect_port 80
}
}
        real_server 192.168.1.104 80 {
        weight 3
        TCP_CHECK {
        connect_timeout 3
        nb_get_retry 3
        delay_before_retry 3
        connect_port 80
}
}
}

LVS-backup的配置文件如下
global_defs {
notification_email {
               [email protected]
        }
        notification_email_from [email protected]
        smtp_server 127.0.0.1
        smtp_connect_timeout 30
        router_id LVS2
}
vrrp_sync_group test {
group {
        loadbalance
}
}

vrrp_instance loadbalance {
        state BACKUP
        interface eth0
        lvs_sync_daemon_inteface eth0
        virtual_router_id 51
        priority 150
        advert_int 5
authentication {
        auth_type PASS
        auth_pass 1111
}
virtual_ipaddress {
        192.168.1.115
}
}

virtual_server 192.168.1.115 80 {
        delay_loop 6
        lb_algo rr
        lb_kind DR
        #persistence_timeout 20
        protocol TCP
        real_server 192.168.1.105 80 {
        weight 3
        TCP_CHECK {
        connect_timeout 3
        nb_get_retry 3
        delay_before_retry 3
        connect_port 80
}
}
        real_server 192.168.1.103 80 {
        weight 3
        TCP_CHECK {
        connect_timeout 3
        nb_get_retry 3
        delay_before_retry 3
        connect_port 80
}
}
        real_server 192.168.1.104 80 {
        weight 3
        TCP_CHECK {
        connect_timeout 3
        nb_get_retry 3
        delay_before_retry 3
        connect_port 80
}
}
}
     
6.         Realserver的配置
三台客户端的脚本都一样！
cat /etc/rc.d/init.d/realserver.sh
#!/bin/bash
# description: Config realserver lo and apply noarp

SNS_VIP=192.168.1.115

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

case "$1" in
start)
       ifconfig lo:0 $SNS_VIP netmask 255.255.255.255 broadcast $SNS_VIP
       /sbin/route add -host $SNS_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 $SNS_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"
       ;;
*)
       echo "Usage: $0 {start|stop}"
       exit 1
esac

exit 0

7.         测试
1)        首先测试各个readserver，确定各个readserver都能正常访问，测试realserver.sh脚本，看启动后 能不能绑定lvs vip，停止后能不能去除绑定的vip
2)        测试lvs能否进行负载均衡转发，利用ipvsadm命令查看，如果想只当当前的 请求转发到哪个服务器去了，可以用ipvsadm加选项来查看，其完整形式为：ipvsadm –lcn | grep 192.168.1.115
3)        停掉主lvs看lvs backup是否接管！
4)        更详细信息请查看日志，tail -f /var/log/messages