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lvs-keepalived

前言

LVS工作在网络层，通过控制IP来实现负载均衡。IPVS是其具体的实现模块。IPVS的主要作用：安装在Director Server上面，在Director Server虚拟一个对外访问的IP（VIP）。用户访问VIP，到达Director Server，Director Server根据一定的规则选择一个Real Server，处理完成后然后返回给客户端数据。

IPVS有三种机制：NAT，TUN，DR

DR Direct server在VIP:80端口监听用户请求，改写请求报文的MAC地址，将请求负载到real server上，real server将响应直接返回给用户，因此所有的主机必须在同一个网段，且real server可以直接与用户通信。

四种分配方法：

  • Round robin (RRS)

将工作平均的分配到服务器 (用于实际服务主机性能一致)

  • Least-connections (LCS)

向较少连接的服务器分配较多的工作(IPVS 表存储了所有的活动的连接。用于实际服务主机性能一致。)

  • Weighted round robin (WRRS)

向较大容量的服务器分配较多的工作。可以根据负载信息动态的向上或向下调整。 (用于实际服务主机性能不一致时)

  • Weighted least-connections (WLC)

考虑它们的容量向较少连接的服务器分配较多的工作。容量通过用户指定的砝码来说明，可以根据装载信息动态的向上或向下调整。(用于实际服务主机性能不一致时)

部署

节点布局

名称 IP
lvs-master 192.168.100.80
lvs-backup 192.168.100.81
realserver1 192.168.100.82
realserver2 192.168.100.83
lvs-vip 192.168.100.88

在realserver绑定虚拟ip地址，脚本如下：

cat realserver
#!/bin/bash  
SNS_VIP=192.168.100.88 
. /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

keepalived.conf配置文件参考

! Configuration File for keepalived

global_defs {
   notification_email {
     gencat@163.com
   }
   notification_email_from lvs@localhost
   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 {
        192.168.100.88
    }
}

virtual_server 192.168.100.88 80 {  
    delay_loop 6                    
    lb_algo wrr                    
    lb_kind DR                    
    persistence_timeout 60          
    protocol TCP                  
    real_server 192.168.100.82 80 {  
        weight 3                 
        TCP_CHECK {  
        connect_timeout 10         
        nb_get_retry 3  
        delay_before_retry 3  
        connect_port 80  
        }  
    }  
    real_server 192.168.100.83 80 {  
        weight 3  
        TCP_CHECK {  
        connect_timeout 10  
        nb_get_retry 3  
        delay_before_retry 3  
        connect_port 80  
        }  
     }  
}

安装lvs-keepalived,采用yum方式，版本已经稳定，采用clush工具

在 /etc/clustershell/groups添加对应信息，便于统一部署
lvs: lvs-master lvs-backup 
lvs-rs: rs[1-2]

clush -b -w @lvs yum -y install ipvsadm keepalived

#priority 100决定优先级，比如master 100,backup 99
clush -w lvs-master -c keepalived.conf --dest=/etc/keepalived

#修改priority 99，state MASTER -> BACKUP 复制到 lvs_backup
clush -w lvs-backup -c keepalived.conf --dest=/etc/keepalived

web服务器简单搭建

clush -b -w @lvs-rs yum -y install httpd
clush -b -w @lvs-rs "echo this is test > /var/www/html/index.html"
clush -b -w @lvs-rs  "hostname >> /var/www/html/index.html"
clusb -b -w @lvs-rs service httpd start

检测

负载分流检验

clush -b -w @app curl http://192.168.100.88  

---------------
app[13,16,18,201] (4)
---------------
This is test
rs2
---------------
app[14-15,17,200] (4)
---------------
This is test
rs1

状态检测

clush -b -w @lvs ipvsadm -ln

---------------
lvs-backup
---------------
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  192.168.100.88:80 wrr persistent 60
  -> 192.168.100.82:80            Route   3      0          0         
  -> 192.168.100.83:80            Route   3      0          0         
---------------
lvs-master
---------------
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  192.168.100.88:80 wrr persistent 60
  -> 192.168.100.82:80            Route   3      0          4         
  -> 192.168.100.83:80            Route   3      0          4

lvs稳定性检测

#clush -w lvs-master service keepalived stop
lvs-master: Stopping keepalived: [  OK  ]

# clush -b -w @app curl http://192.168.100.88
---------------
app[13,15,18,201] (4)
---------------
This is test
rs1
---------------
app[14,16-17,200] (4)
---------------
This is test
rs2

# clush -b -w @lvs ipvsadm -ln

---------------
lvs-backup
---------------
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  192.168.100.88:80 wrr persistent 60
  -> 192.168.100.82:80            Route   3      0          4         
  -> 192.168.100.83:80            Route   3      0          4         
---------------
lvs-master
---------------
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn

web节点测试

# clush -b -w rs1 service httpd stop
# 对应邮件会收到 => TCP CHECK failed on service <=  报警提示

# clush -b -w @app curl http://192.168.100.88
---------------
app[13-18,200-201] (8)
---------------
This is test
rs2

# clush -b -w @lvs ipvsadm -ln
---------------
lvs-backup
---------------
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  192.168.100.88:80 wrr persistent 60
  -> 192.168.100.83:80            Route   3      0          8         
---------------
lvs-master
---------------
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn

keepalived 多VIP切换

配置参考

vrrp_script web1_check
{
    script "/etc/keepalived/web1_check.sh"
    interval 1
    weigh -2
}

vrrp_script web2_check
{
    script "/etc/keepalived/web2_check.sh"
    interval 1
    weigh -2
}

vrrp_instance webone {
    state MASTER
    interface eth0
    virtual_router_id 38
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 017181
    }
    track_script
    {
        web1_check
    }

    virtual_ipaddress {
      10.57.17.181
    }
}


vrrp_instance webtwo {
    state MASTER
    interface eth0
    virtual_router_id 39
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 017182
    }
    track_script
    {
        web2_check
    }
    virtual_ipaddress {
      10.57.17.182
    }
}

检测脚本

＃exit 0 则不触发脚本
＃exit 1 则触发下一步，如 权重 －2

cat web1_check.sh

#!/bin/sh
exit `cat /tmp/web1`

效果

每个vrrp_instance 实例单独根据检测脚本切换权重，适合单机启动多个实例需要自动切换的情况。