搭建LVS负载均衡环境（keepalived+lvs+nginx)

标签：lvs配置   keepalived+lvs+nginx   lvs详解   

LVS简介：

LVS集群有DR、TUN、NAT三种配置模式，可以对www服务、FTP服务、MAIL服务等做负载均衡，下面通过搭建www服务的负载均衡实例，讲述基于DR模式的LVS集群配置

Director-Server: LVS的核心服务器，作用类似于一个路由器，含有为LVS功能完成的路由表，通过路由表把用户的请求分发给服务器组层的应用服务器（Real_Server),同时监控Real-servers

，在Real-Server不可用时，将其从LVS路由表中剔除，再恢复时，重新加入。

Real-Server:由web服务器，mail服务器，FTP服务器，DNS服务器，视频服务器中的一个或多个，每个Real-Server通过LAN分布或WAN分布相连接。实际过程中DR，也可以同时兼任Real-server

LVS的三种负载均衡方式：

NAT：调度器将请求的目标地址和目标端口，改写成Real-server的地址和端口，然后发送到选定的Real-server上，Real-Server端将数据返回给用户时，需要再次经过DR将报文的源地址和源端口改成虚拟IP的地址和端口，然后把数据发送给用户，完成整个负载调度过程。

弊端：调度器负载大

TUN: IP隧道方式，调度器将请求通过IP隧道转发到Real-server，而Real-server直接响应用户的请求，不再经调度器。D与R可不同网络，TUN方式中，调度器将只处理用户的报文请求，提高吞吐量。

弊端：有IP隧道开销

DR：直接路由技术实现虚拟服务器，DR通过改写请求的MAC，将请求发送给Real-server，而Real-server直接响应给Client，免去了隧道开销。三种方式中，效果最好。

弊端：要求D与R同在一个物理网段

LVS的负载调度方式：

LVS是根据Real-Server的负载情况，动态的选择Real-server响应，IPVS实现了8种负载调度算法，这里讲述4种调度算法：

rr 轮叫调度：

平等分配R，不考虑负载。

wrr 加权轮叫调度：

设置高低权值，分配给R。

lc 最少连接调度：

动态分配给已建立连接少的R上。

wlc 加权最少连接调度：

动态的设置R的权值，在分配新连接请求时，尽可能使R的已建立连接和R的权值成正比。

环境介绍：

本例使用三台主机，一台Director-server（调度服务器），两台web real_server（web服务器）

DS的真实IP：10.2.16.250 

       VIP：10.2.16.252

RealServer——1 的真实IP： 10.2.16.253

RealServer——2 的真实IP： 10.2.16.254

注意：本例采用LVS的DR模式，使用rr轮询来做负载均衡

用keepalived方式安装配置LVS

1、安装keepalived

[root@proxy ~]# tar -zxvf keepalived-1.2.13.tar.gz -C ./

[root@proxy ~]# cd keepalived-1.2.13

[root@proxy keepalived-1.2.13]# ./configure --sysconf=/etc/ --with-kernel-dir=/usr/src/kernels/2.6.32-358.el6.x86_64/

[root@proxy keepalived-1.2.13]# make && make install

[root@proxy keepalived-1.2.13]# ln /usr/local/sbin/keepalived /sbin/

2、安装LVS

 yum -y install ipvsadm*

 开启路由转发功能：

[root@proxy ~]# vim /etc/sysctl.conf

 net.ipv4.ip_forward = 1

[root@proxy ~]# sysctl -p

3、在调度服务器上配置keepalived和LVS

[root@proxy ~]# cat /etc/keepalived/keepalived.conf 

! Configuration File for keepalived

global_defs {

   notification_email {

     sysadmin@firewall.loc

   }

   notification_email_from Alexandre.Cassen@firewall.loc

   smtp_server 127.0.0.1

   smtp_connect_timeout 30

   router_id LVS_DEVEL

}

vrrp_instance VI_1 {

    state MASTER

    interface eth0 #LVS的真实物理网卡

    virtual_router_id 51

    priority 100

    advert_int 1

    authentication {

        auth_type PASS

        auth_pass 1111

    }

    virtual_ipaddress {   #LVS的VIP

10.2.16.252

    }

}

virtual_server 10.2.16.252 80 {         #定义对外提供服务的LVS的VIP以及port

    delay_loop 6 #设置运行情况检查时间，单位是s

    lb_algo rr #设置负载调度算法，RR为轮询调度

    lb_kind DR #设置LVS的负载均衡机制，NAT/TUN/DR 三种模式

    nat_mask 255.255.255.0

#    persistence_timeout 50             #会话保持时间，单位是s，对动态网页的session共享有用

    protocol TCP #指定转发协议类型

    real_server 10.2.16.253 80 {         #指定realserver的真实IP和port

        weight 1  #设置权值，数字越大分配的几率越高

TCP_CHECK {  #realserver的状态检测部分

            connect_timeout 3 #表示3秒无响应超时

            nb_get_retry 3  #重试次数

            delay_before_retry 3 #重试间隔

        }

    }

    real_server 10.2.16.254 80 {         #配置服务节点2

        weight 1

TCP_CHECK {

            connect_timeout 3

            nb_get_retry 3

            delay_before_retry 3

        }

    }

}

4、配置Real_Server

  由于采用的是DR方式调度，Real_Server会以LVS的VIP来直接回复Client，所以需要在Real_Server的lo上开启LVS的VIP来与Client建立通信

1、此处写了一个脚本来实现VIP这项功能：

[root@web-1 ~]# cat /etc/init.d/lvsrs 

#!/bin/bash

#description : start Real Server

VIP=10.2.16.252

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

case "$1" in 

start)

echo " Start LVS of Real Server "

/sbin/ifconfig lo:0 $VIP broadcast $VIP netmask 255.255.255.255 up

/sbin/route add -host $VIP dev lo:0

echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore                 #注释：这四句目的是为了关闭ARP广播响应，使VIP不能向网络内发送广播，以防止网络出现混乱

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

;;

stop)

/sbin/ifconfig lo:0 down

echo "close LVS Director server"

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 "Usage: $0 {start|stop}"

exit 1

esac

2、启动脚本：

[root@web-1 ~]# service lvsrs start

 Start LVS of Real Server 

3、查看lo:0虚拟网卡的IP：

  [root@web-1 ~]# ifconfig 

eth0      Link encap:Ethernet  HWaddr 00:0C:29:A2:C4:9F  

          inet addr:10.2.16.253  Bcast:10.2.16.255  Mask:255.255.255.0

          inet6 addr: fe80::20c:29ff:fea2:c49f/64 Scope:Link

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          RX packets:365834 errors:0 dropped:0 overruns:0 frame:0

          TX packets:43393 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000 

          RX bytes:33998241 (32.4 MiB)  TX bytes:4007256 (3.8 MiB)

lo        Link encap:Local Loopback  

          inet addr:127.0.0.1  Mask:255.0.0.0

          inet6 addr: ::1/128 Scope:Host

          UP LOOPBACK RUNNING  MTU:16436  Metric:1

          RX packets:17 errors:0 dropped:0 overruns:0 frame:0

          TX packets:17 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0 

          RX bytes:1482 (1.4 KiB)  TX bytes:1482 (1.4 KiB)

lo:0      Link encap:Local Loopback  

          inet addr:10.2.16.252  Mask:255.255.255.255

          UP LOOPBACK RUNNING  MTU:16436  Metric:1

4、确保nginx访问正常

[root@web-1 ~]# netstat -anptul

Active Internet connections (servers and established)

Proto Recv-Q Send-Q Local Address               Foreign Address             State       PID/Program name   

tcp        0      0 0.0.0.0:80                  0.0.0.0:*                   LISTEN      1024/nginx          

5、在real_server2上，执行同样的4步操作。

6、开启DR上的keepalived：

[root@proxy ~]# service keepalived start

Starting keepalived:                                       [  OK  ]

查看keepalived启动日志是否正常：

[root@proxy ~]# tail -f /var/log/messeges

May 24 10:06:57 proxy Keepalived[2767]: Starting Keepalived v1.2.13 (05/24,2014)

May 24 10:06:57 proxy Keepalived[2768]: Starting Healthcheck child process, pid=2770

May 24 10:06:57 proxy Keepalived[2768]: Starting VRRP child process, pid=2771

May 24 10:06:57 proxy Keepalived_healthcheckers[2770]: Netlink reflector reports IP 10.2.16.250 added

May 24 10:06:57 proxy Keepalived_vrrp[2771]: Netlink reflector reports IP 10.2.16.250 added

May 24 10:06:57 proxy Keepalived_healthcheckers[2770]: Netlink reflector reports IP fe80::20c:29ff:fee6:ce1a added

May 24 10:06:57 proxy Keepalived_healthcheckers[2770]: Registering Kernel netlink reflector

May 24 10:06:57 proxy Keepalived_healthcheckers[2770]: Registering Kernel netlink command channel

May 24 10:06:57 proxy Keepalived_vrrp[2771]: Netlink reflector reports IP fe80::20c:29ff:fee6:ce1a added

May 24 10:06:57 proxy Keepalived_vrrp[2771]: Registering Kernel netlink reflector

May 24 10:06:57 proxy Keepalived_vrrp[2771]: Registering Kernel netlink command channel

May 24 10:06:57 proxy Keepalived_vrrp[2771]: Registering gratuitous ARP shared channel

May 24 10:06:57 proxy Keepalived_vrrp[2771]: Opening file ‘/etc/keepalived/keepalived.conf‘.

May 24 10:06:57 proxy Keepalived_vrrp[2771]: Configuration is using : 63303 Bytes

May 24 10:06:57 proxy Keepalived_vrrp[2771]: Using LinkWatch kernel netlink reflector...

May 24 10:06:57 proxy Keepalived_healthcheckers[2770]: Opening file ‘/etc/keepalived/keepalived.conf‘.

May 24 10:06:57 proxy Keepalived_healthcheckers[2770]: Configuration is using : 14558 Bytes

May 24 10:06:57 proxy Keepalived_vrrp[2771]: VRRP sockpool: [ifindex(2), proto(112), unicast(0), fd(10,11)]

May 24 10:06:57 proxy Keepalived_healthcheckers[2770]: Using LinkWatch kernel netlink reflector...

May 24 10:06:57 proxy Keepalived_healthcheckers[2770]: Activating healthchecker for service [10.2.16.253]:80

May 24 10:06:57 proxy Keepalived_healthcheckers[2770]: Activating healthchecker for service [10.2.16.254]:80

May 24 10:06:58 proxy Keepalived_vrrp[2771]: VRRP_Instance(VI_1) Transition to MASTER STATE

May 24 10:06:59 proxy Keepalived_vrrp[2771]: VRRP_Instance(VI_1) Entering MASTER STATE

May 24 10:06:59 proxy Keepalived_vrrp[2771]: VRRP_Instance(VI_1) setting protocol VIPs.

May 24 10:06:59 proxy Keepalived_vrrp[2771]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 10.2.16.252

May 24 10:06:59 proxy Keepalived_healthcheckers[2770]: Netlink reflector reports IP 10.2.16.252 added

May 24 10:07:04 proxy Keepalived_vrrp[2771]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 10.2.16.252

 一切正常！

 7、查看LVS的路由表：

 [root@proxy ~]# ipvsadm -ln

IP Virtual Server version 1.2.1 (size=4096)

Prot LocalAddress:Port Scheduler Flags

  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn

TCP  10.2.16.252:80 rr

  -> 10.2.16.253:80               Route   1      0          0         

  -> 10.2.16.254:80               Route   1      0          0         

 8、测试，打开网页，输入 http://10.2.16.252/

 能正常出现两台负载均衡服务器的网页，则证明已经成功！

 9、测试其中一台Real-Server服务挂掉

  （1）把254的nginx进程杀掉，再开启。

  （2）查看keepalived的日志：

[root@proxy ~]#tail -f /var/log/messeges 

May 24 10:10:55 proxy Keepalived_healthcheckers[2770]: TCP connection to [10.2.16.254]:80 failed !!!

May 24 10:10:55 proxy Keepalived_healthcheckers[2770]: Removing service [10.2.16.254]:80 from VS [10.2.16.252]:80

May 24 10:10:55 proxy Keepalived_healthcheckers[2770]: Remote SMTP server [127.0.0.1]:25 connected.

May 24 10:10:55 proxy Keepalived_healthcheckers[2770]: SMTP alert successfully sent.

May 24 10:11:43 proxy Keepalived_healthcheckers[2770]: TCP connection to [10.2.16.254]:80 success.

May 24 10:11:43 proxy Keepalived_healthcheckers[2770]: Adding service [10.2.16.254]:80 to VS [10.2.16.252]:80

May 24 10:11:43 proxy Keepalived_healthcheckers[2770]: Remote SMTP server [127.0.0.1]:25 connected.

May 24 10:11:43 proxy Keepalived_healthcheckers[2770]: SMTP alert successfully sent.

 可见keepalive的反应速度还是非常快的！

到此，LVS配置全部结束，圆满成功！

本文出自 “Fate” 博客，请务必保留此出处http://czybl.blog.51cto.com/4283444/1536474

搭建LVS负载均衡环境（keepalived+lvs+nginx),布布扣,bubuko.com

搭建LVS负载均衡环境（keepalived+lvs+nginx)

标签：lvs配置   keepalived+lvs+nginx   lvs详解   

原文地址：http://czybl.blog.51cto.com/4283444/1536474