LVS+keepalived搭建负载均衡学习手札(二)

上次做了LVS+keepalived的负载均衡,效果还不错,但是没有做主备,这次补上:

安装环境:环境 centos4.4

一共准备四台机器:

负载均衡机器:

主:192.168.2.158              #安装lvs+keepalived

备:192.168.2.159              #安装lvs+keepalived

VIP:192.168.2.188

real-server1:192.168.2.187    #仅执行脚本

real-server2:192.168.2.189    #仅执行脚本


安装过程:

在192.168.2.159上安装ipvsadm和keepalived,方法不再赘述,主要看keepalived的配置:

 

! Configuration File for keepalived
 

global_defs {

   notification_email {
   [email protected]                        #邮件地址,需要本机开启SMTP服务
   }
   notification_email_from root@localhost
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id LVS_DEVEL2                  #负载均衡器标示:同一局域网内,应该是唯一的。
}

 
vrrp_sync_group VGM {      
   group {
      VI_1
   }
}
 
vrrp_instance VI_1 {
    state BACKUP                      
 #设置为BACKUP,通过priority控制那台提升为主。
    interface eth0
    virtual_router_id 51
    priority 70
    advert_int 5
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.2.188
    }
}
 
virtual_server 192.168.2.188 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    persistence_timeout 50
    protocol TCP
  
 real_server 192.168.2.187 80 {
        weight 3
        TCP_CHECK {
        nb_get_retry 3
        delay_before_retry 3
        connect_port 80
        connect_timeout 3
        }
    }
    real_server 192.168.2.189 80 {
        weight 1
        TCP_CHECK {
        nb_get_retry 3
        delay_before_retry 3
        connect_port 80
        connect_timeout 3
 
        }
    }
}
红色标记为需要修改的地方。
执行/etc/init.d/keepalived start
 
附上备机keepalived的启动日志:
Oct 22 23:40:35 test1 Keepalived: Starting Keepalived v1.1.17 (10/22,2009)
Oct 22 23:40:35 test1 Keepalived_healthcheckers: Using MII-BMSR NIC polling thread...
Oct 22 23:40:35 test1 Keepalived_healthcheckers: Netlink reflector reports IP 192.168.2.187 added
Oct 22 23:40:35 test1 Keepalived_healthcheckers: Registering Kernel netlink reflector
Oct 22 23:40:35 test1 Keepalived_healthcheckers: Registering Kernel netlink command channel
Oct 22 23:40:35 test1 keepalived: keepalived startup succeeded
Oct 22 23:40:35 test1 Keepalived_healthcheckers: Opening file '/etc/keepalived/keepalived.conf'.
Oct 22 23:40:35 test1 Keepalived_healthcheckers: Configuration is using : 10675 Bytes
Oct 22 23:40:35 test1 Keepalived_healthcheckers: Activating healtchecker for service [192.168.2.187:80]
Oct 22 23:40:35 test1 Keepalived_healthcheckers: Activating healtchecker for service [192.168.2.189:80]
Oct 22 23:40:35 test1 Keepalived: Starting Healthcheck child process, pid=5387
Oct 22 23:40:35 test1 Keepalived_vrrp: Using MII-BMSR NIC polling thread...
Oct 22 23:40:35 test1 Keepalived_vrrp: Netlink reflector reports IP 192.168.2.187 added
Oct 22 23:40:35 test1 Keepalived_vrrp: Registering Kernel netlink reflector
Oct 22 23:40:35 test1 Keepalived: Starting VRRP child process, pid=5389
Oct 22 23:40:35 test1 Keepalived_vrrp: Registering Kernel netlink command channel
Oct 22 23:40:35 test1 Keepalived_vrrp: Registering gratutious ARP shared channel
Oct 22 23:40:35 test1 Keepalived_vrrp: Opening file '/etc/keepalived/keepalived.conf'.
Oct 22 23:40:35 test1 Keepalived_vrrp: Configuration is using : 37155 Bytes
Oct 22 23:40:35 test1 Keepalived_vrrp: VRRP_Instance(VI_1) Entering BACKUP STATE
Oct 22 23:40:35 test1 Keepalived_vrrp: VRRP sockpool: [ifindex(2), proto(112), fd(10,11)]
 
当停掉主负载均衡时,备机负载均衡的接管日志:
Oct 22 23:42:18 test1 Keepalived_vrrp: VRRP_Instance(VI_1) Transition to MASTER STATE
Oct 22 23:42:18 test1 Keepalived_vrrp: VRRP_Group(VGB) Syncing instances to MASTER state
Oct 22 23:42:23 test1 Keepalived_vrrp: VRRP_Instance(VI_1) Entering MASTER STATE
Oct 22 23:42:23 test1 Keepalived_vrrp: VRRP_Instance(VI_1) setting protocol VIPs.
Oct 22 23:42:23 test1 Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.2.188
Oct 22 23:42:23 test1 Keepalived_vrrp: Netlink reflector reports IP 192.168.2.188 added
Oct 22 23:42:23 test1 Keepalived_healthcheckers: Netlink reflector reports IP 192.168.2.188 added
Oct 22 23:42:28 test1 Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.2.188

 

当重启主负载均衡时,备机负载均衡的日志:

Oct 22 23:43:18 test1 Keepalived_vrrp: VRRP_Instance(VI_1) Received higher prio advert
Oct 22 23:43:18 test1 Keepalived_vrrp: VRRP_Instance(VI_1) Entering BACKUP STATE
Oct 22 23:43:18 test1 Keepalived_vrrp: VRRP_Instance(VI_1) removing protocol VIPs.
Oct 22 23:43:18 test1 Keepalived_vrrp: VRRP_Group(VGB) Syncing instances to BACKUP state
Oct 22 23:43:18 test1 Keepalived_vrrp: Netlink reflector reports IP 192.168.2.188 removed
Oct 22 23:43:18 test1 Keepalived_healthcheckers: Netlink reflector reports IP 192.168.2.188 removed

 

以上就完成双机热备的Lvs+keepalived的负载均衡。

relserver上需要执行的脚本:

[root@test1 ~]# more /usr/local/bin/lvs_real
#!/bin/sh
VIP=192.168.2.188              (直接路由模式的vip必须跟服务器对外提供服务的ip地址在同一个网段)
/etc/rc.d/init.d/functions
case "$1" in
start)
    echo " start tunl port"
    ifconfig lo:0 $VIP netmask 255.255.255.255 broadcast $VIP up

   (如果有多VIP,依次往下写)
    echo "2">/proc/sys/net/ipv4/conf/all/arp_announce
    echo "1">/proc/sys/net/ipv4/conf/all/arp_ignore
    echo "2">/proc/sys/net/ipv4/conf/lo/arp_announce
    echo "1">/proc/sys/net/ipv4/conf/lo/arp_ignore
    ;;
stop)
    echo " stop tunl port"
    ifconfig lo:0 down
    echo "0">/proc/sys/net/ipv4/conf/all/arp_announce
    echo "0">/proc/sys/net/ipv4/conf/all/arp_ignore
    echo "0">/proc/sys/net/ipv4/conf/lo/arp_announce
    echo "0">/proc/sys/net/ipv4/conf/lo/arp_ignore
    ;;

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

总结:只需在负载均衡机器上安装ipvsadm和keepalived,并执行keepalived启动。在real server机器上仅需开启本地回环地址(脚本)即可,不用安装任何软件。

经验:千万不要将负载均衡机器和web服务器搭建在一起,虽然端口等都不冲突,但是会出现莫名其妙的问题..

1.real server上未执行此脚本时:
[root@linux keepalived]# ifconfig lo:0
lo:0      Link encap:Local Loopback 
          UP LOOPBACK RUNNING  MTU:16436  Metric:1

2.real server上执行此脚本后:
[root@linux keepalived]# /usr/local/bin/lvs_real start
 start tunl port
[root@YuHao-linux keepalived]# ifconfig lo:0
lo:0      Link encap:Local Loopback 
          inet addr:192.168.2.188  Mask:255.255.255.255
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
所以:
keepalive机器上不用执行此脚本,因为在keepalived.conf中已经定义了vip地址,
而real server机器上必须执行此脚本。将虚拟IP绑定在本机回环网卡上。

这里还需注意一下MAC地址的问题(netseek):
假如两台VS之间使用的互备关系,那么当一台VS接管LVS服务时,可能会网络不通,这时因为路由器的MAC缓存表里无法及时刷新MAC.关于vip这个地址的MAC地址还是替换的VS的MAC,有两种解决方法,一种是修改新VS的MAC地
址,另一种是使用 send_arp /arpiing 命令.
以arping 命令为例.
/sbin/arping -I eth0 -c 3 -s ${vip}${gateway_ip} > /dev/null 2>&1
Eg:
/sbin/arping -I eth0 -c 3 -s 192.168.1.6192.168.1.1

如果采用Piranha/keealived方案切换的时候会内置自动发送 send_arp命令.UltraMonkey方案经测试也会自动发送此命令.如用 heartbeat方案,需要写一个send_arp 或者arping 相关的脚本当作heartbeat 一个资源切换服务的时候自动发送相关命令脚本.

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