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LVS+Keepalived高可用负载均衡集群架构

时间:2015-01-26 10:23来源:51cto 编辑:linuxeye 点击:
实验环境: LVS和keepalived介绍: 1.keepalived的设计目标是构建高可用的LVS负载均衡群集,可以调用ipvsadm工具来创建虚拟服务器,管理服务器池,而不仅仅用来做双机热备。 使用keepalived构

实验环境:

LVS和keepalived介绍:

1.keepalived的设计目标是构建高可用的LVS负载均衡群集,可以调用ipvsadm工具来创建虚拟服务器,管理服务器池,而不仅仅用来做双机热备。

使用keepalived构建LVS群集更加简便易用,主要优势体现在:

对LVS负载调度器实现热备切换,提高可用性;

对服务器池中的节点进行健康检查,自动移除失效节点,恢复后再重新加入。

 

2. 在基于LVS+Keepalived实现的LVS群集结构中,至少包括两台热备的负载调度器,两台以上的节点服务器,本例将以DR模式的LVS群集为基 础,增加一台从负载调度器,使用Keepalived来实现主、从调度器的热备,从而构建建有负载均衡、高可用两种能力的LVS网站群集平台。

 

3. 通过LVS+Keepalived构建的LVS集群,LVS负载均衡用户请求到后端tomcat服务器,Keepalived的作用是检测web服务器的 状态,如果有一台web服务器死机,或工作出现故障,Keepalived将检测到,并将有故障的web服务器从系统中剔除,当web服务器工作正常后 Keepalived自动将web服务器加入到服务器群中,这些工作全部自动完成,不需要人工干涉,需要人工做的只是修复故障的web服务器。

 

Keepalived简介

什 么是Keepalived:keepalived可以实现服务的高可用或热备,用来防止单点故障的问题;而Keepalived的核心VRRP协 议,VRRP协议主要实现了在路由器或三层交换机处的冗余;Keepalived就是使用VRRP协议来实现高可用的;下面一起来看一下 Keepalived的原理图:

 

Keepalived启动后会有三个进程:

    父进程:内存管理,子进程管理

    子进程:VRRP子进程

    子进程:healthchecker子进程

由上图可知:

    两 个子进程都被系统WatchDog看管,两个子进程各自复杂自己的事,healthchecker子进程复杂检查各自服务器的健康程度,例如 HTTP,LVS等,如果healthchecker子进程检查到MASTER上服务不可用了,就会通知本机上的VRRP子进程,让它删除通告,并且去掉 虚拟IP,转换为BACKUP状态;

实验架构图:

实验过程:

HA高可用集群构建前提:

1.proxy和proxy2节点时间必须同步;

建议使用ntp协议进行;

 

2、节点之间必须要通过主机名互相通信;

建议使用hosts文件;

通信中使用的名字必须与其节点为上“uname -n”命令展示出的名字保持一致;

[root@proxy ~]# cat /etc/hosts                        
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
172.16.0.1  server.magelinux.com server
172.16.31.52 proxy.stu31.com proxy
172.16.31.53 proxy2.stu31.com proxy2
172.16.31.50 tom1.stu31.com tom1
172.16.31.51 tom2.stu31.com tom2


3、节点之间彼此root用户能基于ssh密钥方式进行通信;

节点proxy:
# ssh-keygen -t rsa -P ""
# ssh-copy-id -i .ssh/id_rsa.pub proxy2
节点proxy2:
# ssh-keygen -t rsa -P ""
# ssh-copy-id -i .ssh/id_rsa.pub proxy
测试ssh无密钥通信:
[root@proxy ~]# date ; ssh proxy2 date
Sat Jan 17 15:29:26 CST 2015
Sat Jan 17 15:29:26 CST 2015
一.配置安装LVS+keepalived
1.在Master与Backup服务器上分别安装Ipvsadm、Keepalived软件包、这里使用的是yum安装方式
# yum install -y keepalived ipvsadm
注释:这里安装Ipvsadm工具主要是为了查看lvs规则使用,不安装ipvsadm工具也能成功配置规则,但不方便;

2.修改keepalived配置文件
keepalived的文件路径/etc/keepalived/keepalived.conf

修改Master节点proxy的主配置文件
[root@proxy ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
   notification_email {      #设置报警通知邮件地址,可以设置多个
    root@localhost
   }
   notification_email_from admin@stu31.com  #设置邮件的发送地址
   smtp_server 127.0.0.1        #设置smtp server的地址,该地址必须是存在的
   smtp_connect_timeout 30      #设置连接smtp server的超时时间
   router_id LVS_DEVEL          #运行Keepalived服务器的标识,发邮件时显示在邮件标题中的信息
}
vrrp_instance VI_1 {            #定义VRRP实例,实例名自定义
    state MASTER                #指定Keepalived的角色,MASTER为主服务器,BACKUP为备用服务器
    interface eth0              #指定HA监测的接口
    virtual_router_id 51        #虚拟路由标识,这个标识是一个数字(1-255),在一个VRRP实例中主备服务器ID必须一样
    priority 100                #优先级,数字越大优先级越高,在一个实例中主服务器优先级要高于备服务器
    advert_int 1                #设置主备之间同步检查的时间间隔单位秒
    authentication {            #设置验证类型和密码
        auth_type PASS          #验证类型有两种{PASS|HA}
        auth_pass oracle        #设置验证密码,在一个实例中主备密码保持一样
    }
    virtual_ipaddress {         #定义虚拟IP地址,可以有多个,每行一个
    172.16.31.188
    }
}
virtual_server 172.16.31.188 {    #设置虚拟服务器,需要指定虚拟IP与服务端口,用空格分隔
    delay_loop 6                     #设置健康状态检查时间,单位为秒
    lb_algo rr                       #设置负载高度算法,rr为轮询
    lb_kind DR                       #设置LVS实现负载均衡的机制,可以为{NAT|TUN|DR}三种
    nat_mask 255.255.0.0             #设置掩码
    persistence_timeout 50           #会话保持时间,单位为秒;这个选项对于动态网页是非常有用的,为集群系统中session共享提供了一个很好的解决方案
    protocol TCP                     #指定转发协议类型可以设置{TCP|UDP}两种
    real_server 172.16.31.50 80 {    #后端服务器节点,需要指定Real_server的IP与端口,用空格分隔
        weight 1                     #配置服务节点的权重,数字越大,权重越高
        HTTP_GET {                   #设置检测Realserver的方式为http协议
            url {          
              path /
          status_code 200       #设定返回状态码为200表示Realserver是存活的
            }
            connect_timeout 3        #设置响应超时时间
            nb_get_retry 3           #设置超时重试次数
            delay_before_retry 3     #设置超时后重试间隔
        }
    }
    real_server 172.16.31.51 80 {
        weight 1
        HTTP_GET {
            url {
              path /
          status_code 200
            }
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}
3.将Master服务器proxy节点上的主配置文件拷贝到Backup服务器proxy2节点稍作修改
# scp /etc/keepalived/keepalived.conf proxy2:/etc/keepalived/
######修改如下两项
[root@proxy2 ~]# vim /etc/keepalived/keepalived.conf
state BACKUP
priority 99
4.启动两台服务器上的Keepalived服务并设置为开机自启动
# chkconfig --add keepalived ; ssh proxy2 "chkconfig --add keepalived"
# chkconfig  keepalived on ; ssh proxy2 "chkconfig keepalived on"           
# chkconfig --list keepalived; ssh proxy2 "chkconfig --list keepalived"
keepalived      0:off   1:off   2:on    3:on    4:on    5:on    6:off
keepalived      0:off   1:off   2:on    3:on    4:on    5:on    6:off
启动服务:
# service keepalived start; ssh proxy2 "service keepalived start"
5.观察各节点的服务启动后的日志:
MASTER节点的日志;
[root@proxy keepalived]# tail -f /var/log/messages 
Jan 17 15:57:42 proxy Keepalived[15019]: Starting Keepalived v1.2.13 (10/15,2014)
Jan 17 15:57:42 proxy Keepalived[15021]: Starting Healthcheck child process, pid=15024
Jan 17 15:57:42 proxy Keepalived[15021]: Starting VRRP child process, pid=15025
Jan 17 15:57:42 proxy Keepalived_vrrp[15025]: Netlink reflector reports IP 172.16.31.52 added
Jan 17 15:57:42 proxy Keepalived_vrrp[15025]: Netlink reflector reports IP fe80::a00:27ff:fe3b:2360 added
Jan 17 15:57:42 proxy Keepalived_vrrp[15025]: Registering Kernel netlink reflector
Jan 17 15:57:42 proxy Keepalived_vrrp[15025]: Registering Kernel netlink command channel
Jan 17 15:57:42 proxy Keepalived_vrrp[15025]: Registering gratuitous ARP shared channel
Jan 17 15:57:42 proxy Keepalived_healthcheckers[15024]: Netlink reflector reports IP 172.16.31.52 added
Jan 17 15:57:42 proxy Keepalived_healthcheckers[15024]: Netlink reflector reports IP fe80::a00:27ff:fe3b:2360 added
Jan 17 15:57:42 proxy Keepalived_healthcheckers[15024]: Registering Kernel netlink reflector
Jan 17 15:57:42 proxy Keepalived_healthcheckers[15024]: Registering Kernel netlink command channel
Jan 17 15:57:42 proxy Keepalived_vrrp[15025]: Opening file '/etc/keepalived/keepalived.conf'.
Jan 17 15:57:42 proxy Keepalived_vrrp[15025]: Configuration is using : 63202 Bytes
Jan 17 15:57:42 proxy Keepalived_vrrp[15025]: Using LinkWatch kernel netlink reflector...
Jan 17 15:57:42 proxy Keepalived_healthcheckers[15024]: Opening file '/etc/keepalived/keepalived.conf'.
Jan 17 15:57:42 proxy Keepalived_healthcheckers[15024]: Configuration is using : 16989 Bytes
Jan 17 15:57:42 proxy Keepalived_vrrp[15025]: VRRP sockpool: [ifindex(2), proto(112), unicast(0), fd(10,11)]
Jan 17 15:57:42 proxy Keepalived_healthcheckers[15024]: Using LinkWatch kernel netlink reflector...
Jan 17 15:57:42 proxy Keepalived_healthcheckers[15024]: Activating healthchecker for service [172.16.31.50]:8080
Jan 17 15:57:42 proxy Keepalived_healthcheckers[15024]: Activating healthchecker for service [172.16.31.51]:8080
Jan 17 15:57:43 proxy Keepalived_vrrp[15025]: VRRP_Instance(VI_1) Transition to MASTER STATE
Jan 17 15:57:44 proxy Keepalived_vrrp[15025]: VRRP_Instance(VI_1) Entering MASTER STATE
Jan 17 15:57:44 proxy Keepalived_vrrp[15025]: VRRP_Instance(VI_1) setting protocol VIPs.
Jan 17 15:57:44 proxy Keepalived_healthcheckers[15024]: Netlink reflector reports IP 172.16.31.188 added
Jan 17 15:57:44 proxy Keepalived_vrrp[15025]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 172.16.31.188
BACKUP节点的日志:
[root@proxy2 keepalived]# tail -f /var/log/messages 
Jan 17 15:57:42 proxy2 Keepalived[15005]: Starting Keepalived v1.2.13 (10/15,2014)
Jan 17 15:57:42 proxy2 Keepalived[15007]: Starting Healthcheck child process, pid=15009
Jan 17 15:57:42 proxy2 Keepalived[15007]: Starting VRRP child process, pid=15010
Jan 17 15:57:42 proxy2 Keepalived_vrrp[15010]: Netlink reflector reports IP 172.16.31.53 added
Jan 17 15:57:42 proxy2 Keepalived_healthcheckers[15009]: Netlink reflector reports IP 172.16.31.53 added
Jan 17 15:57:42 proxy2 Keepalived_vrrp[15010]: Netlink reflector reports IP fe80::a00:27ff:fe6e:bd28 added
Jan 17 15:57:42 proxy2 Keepalived_vrrp[15010]: Registering Kernel netlink reflector
Jan 17 15:57:42 proxy2 Keepalived_vrrp[15010]: Registering Kernel netlink command channel
Jan 17 15:57:42 proxy2 Keepalived_vrrp[15010]: Registering gratuitous ARP shared channel
Jan 17 15:57:42 proxy2 Keepalived_healthcheckers[15009]: Netlink reflector reports IP fe80::a00:27ff:fe6e:bd28 added
Jan 17 15:57:42 proxy2 Keepalived_healthcheckers[15009]: Registering Kernel netlink reflector
Jan 17 15:57:42 proxy2 Keepalived_healthcheckers[15009]: Registering Kernel netlink command channel
Jan 17 15:57:42 proxy2 Keepalived_vrrp[15010]: Opening file '/etc/keepalived/keepalived.conf'.
Jan 17 15:57:42 proxy2 Keepalived_healthcheckers[15009]: Opening file '/etc/keepalived/keepalived.conf'.
Jan 17 15:57:42 proxy2 Keepalived_healthcheckers[15009]: Configuration is using : 16991 Bytes
Jan 17 15:57:42 proxy2 Keepalived_vrrp[15010]: Configuration is using : 63204 Bytes
Jan 17 15:57:42 proxy2 Keepalived_vrrp[15010]: Using LinkWatch kernel netlink reflector...
Jan 17 15:57:42 proxy2 Keepalived_vrrp[15010]: VRRP_Instance(VI_1) Entering BACKUP STATE
Jan 17 15:57:42 proxy2 Keepalived_vrrp[15010]: VRRP sockpool: [ifindex(2), proto(112), unicast(0), fd(10,11)]
Jan 17 15:57:42 proxy2 Keepalived_healthcheckers[15009]: Using LinkWatch kernel netlink reflector...
Jan 17 15:57:42 proxy2 Keepalived_healthcheckers[15009]: Activating healthchecker for service [172.16.31.50]:8080
Jan 17 15:57:42 proxy2 Keepalived_healthcheckers[15009]: Activating healthchecker for service [172.16.31.51]:8080
6.开启Master节点与Backup节点服务器的路由转发功能
#sed -i 's/net.ipv4.ip_forward = 0/net.ipv4.ip_forward = 1/g' /etc/sysctl.conf

二.安装配置后端的tomcat服务器节点
1.配置后端tomcat服务器节点;
具体配置参考我的前篇博客,都是连续性的实验;

配置完成后,访问测试如图:

tom2节点:

实现了负载均衡访问;
2.为两台Realserver提供Sysv格式的脚本来自动修改内核参数与虚拟IP并运行脚本

#vim rs.sh
.  /etc/rc.d/init.d/functions
VIP=172.16.31.188
host=`/bin/hostname`
case "$1" in
start)
       # Start LVS-DR real server on this machine.
        /sbin/ifconfig lo down
        /sbin/ifconfig lo up
        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
        /sbin/ifconfig lo:0 $VIP broadcast $VIP netmask 255.255.255.255 up
        /sbin/route add -host $VIP dev lo:0
;;
stop)
        # Stop LVS-DR real server loopback device(s).
        /sbin/ifconfig lo:0 down
        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
;;
status)
        # Status of LVS-DR real server.
        islothere=`/sbin/ifconfig lo:0 | grep $VIP`
        isrothere=`netstat -rn | grep "lo:0" | grep $VIP`
        if [ ! "$islothere" -o ! "isrothere" ];then
            # Either the route or the lo:0 device
            # not found.
            echo "LVS-DR real server Stopped."
        else
            echo "LVS-DR real server Running."
        fi
;;
*)
            # Invalid entry.
            echo "$0: Usage: $0 {start|status|stop}"
            exit 1
;;
esac
注释:脚本中的VIP定义的是虚拟IP地址
3.脚本两个节点都存放一份;然后执行此脚本:
#sh rs.sh start
4.查看设置后的状态:
# sh rs.sh status
LVS-DR real server Running.
查看节点的VIP地址设置完成与否:
tom1节点;
[root@tom1 ~]# ip addr show lo
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet 172.16.31.188/32 brd 172.16.31.188 scope global lo:0
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
tom2节点:
[root@tom2 ~]# ip addr show lo
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet 172.16.31.188/32 brd 172.16.31.188 scope global lo:0
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
5.查看MASTER节点proxy的ipvs规则:
[root@proxy keepalived]# ipvsadm -L -n
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  172.16.31.188:0 rr persistent 50
  -> 172.16.31.50:8080            Route   1      0          0         
  -> 172.16.31.51:8080            Route   1      0          0

从规则中可以看出虚拟IP与Port及调度算法为rr;其中有两个Realserver

三.访问测试及故障模拟ces
1.访问测试:

由上可知,使用的是rr调度算法,在访问测试时可能需要多访问几次或换个浏览器来测试访问

2.模拟Master服务器出现故障,将Master主机上的Keepalived服务停止,查看Backup服务器是否接管所有服务

[root@proxy keepalived]# service keepalived stop   
Stopping keepalived:                                       [  OK  ]
3.观察节点切换后的系统日志:
MASTER节点的日志:
[root@proxy keepalived]# tail -f /var/log/messages 
Jan 17 16:20:40 proxy Keepalived[15021]: Stopping Keepalived v1.2.13 (10/15,2014)
Jan 17 16:20:40 proxy Keepalived_vrrp[15025]: VRRP_Instance(VI_1) sending 0 priority
Jan 17 16:20:40 proxy Keepalived_vrrp[15025]: VRRP_Instance(VI_1) removing protocol VIPs.
Jan 17 16:20:40 proxy Keepalived_healthcheckers[15024]: Netlink reflector reports IP 172.16.31.188 removed
Jan 17 16:20:40 proxy Keepalived_healthcheckers[15024]: Removing service [172.16.31.50]:8080 from VS [172.16.31.188]:0
Jan 17 16:20:40 proxy Keepalived_healthcheckers[15024]: Removing service [172.16.31.51]:8080 from VS [172.16.31.188]:0
Jan 17 16:20:40 proxy kernel: IPVS: __ip_vs_del_service: enter
BACKUP节点的日志:
[root@proxy2 keepalived]# tail -f /var/log/messages 
Jan 17 16:20:41 proxy2 Keepalived_vrrp[15010]: VRRP_Instance(VI_1) Transition to MASTER STATE
Jan 17 16:20:42 proxy2 Keepalived_vrrp[15010]: VRRP_Instance(VI_1) Entering MASTER STATE
Jan 17 16:20:42 proxy2 Keepalived_vrrp[15010]: VRRP_Instance(VI_1) setting protocol VIPs.
Jan 17 16:20:42 proxy2 Keepalived_healthcheckers[15009]: Netlink reflector reports IP 172.16.31.188 added
Jan 17 16:20:42 proxy2 Keepalived_vrrp[15010]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 172.16.31.188
Jan 17 16:20:47 proxy2 Keepalived_vrrp[15010]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 172.16.31.188
4.查看各节点的VIP地址状态及IPVS规则:
原MASTER节点:
[root@proxy keepalived]# ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 08:00:27:3b:23:60 brd ff:ff:ff:ff:ff:ff
    inet 172.16.31.52/16 brd 172.16.255.255 scope global eth0
    inet6 fe80::a00:27ff:fe3b:2360/64 scope link 
       valid_lft forever preferred_lft forever
[root@proxy keepalived]# ipvsadm -L -n
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
由上可见Master服务器上已删除虚拟IP与LVS规则

BACKUP节点:
[root@proxy2 keepalived]# ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 08:00:27:6e:bd:28 brd ff:ff:ff:ff:ff:ff
    inet 172.16.31.53/16 brd 172.16.255.255 scope global eth0
    inet 172.16.31.188/32 scope global eth0
    inet6 fe80::a00:27ff:fe6e:bd28/64 scope link 
       valid_lft forever preferred_lft forever
由上可见,虚拟IP地址已成功在Backup服务器启动
[root@proxy2 keepalived]# ipvsadm -L -n
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  172.16.31.188:0 rr persistent 50
  -> 172.16.31.50:8080            Route   1      0          0         
  -> 172.16.31.51:8080            Route   1      0          0
LVS的规则也已成功配置在Backup服务器上面

5.再次访问测试服务器是否正常提供服务

6.假如Master服务器修复好已重新上线,则虚拟IP地址与LVS规则会重新配置到Master服务器上而在Backup服务器上删除

[root@proxy keepalived]# service keepalived start
Starting keepalived:                                       [  OK  ]
观察启动日志:
MASTER节点的日志:
[root@proxy keepalived]# tail -f /var/log/messages 
Jan 17 16:34:50 proxy Keepalived_vrrp[15366]: VRRP_Instance(VI_1) Transition to MASTER STATE
Jan 17 16:34:50 proxy Keepalived_vrrp[15366]: VRRP_Instance(VI_1) Received lower prio advert, forcing new election
Jan 17 16:34:51 proxy Keepalived_vrrp[15366]: VRRP_Instance(VI_1) Entering MASTER STATE
Jan 17 16:34:51 proxy Keepalived_vrrp[15366]: VRRP_Instance(VI_1) setting protocol VIPs.
Jan 17 16:34:51 proxy Keepalived_vrrp[15366]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 172.16.31.188
Jan 17 16:34:51 proxy Keepalived_healthcheckers[15365]: Netlink reflector reports IP 172.16.31.188 added
Jan 17 16:34:56 proxy Keepalived_vrrp[15366]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 172.16.31.188
自动进入了MASTER状态;
BACKUP节点的日志:
[root@proxy2 keepalived]# tail -f /var/log/messages 
Jan 17 16:34:50 proxy2 Keepalived_vrrp[15258]: VRRP_Instance(VI_1) Received higher prio advert
Jan 17 16:34:50 proxy2 Keepalived_vrrp[15258]: VRRP_Instance(VI_1) Entering BACKUP STATE
Jan 17 16:34:50 proxy2 Keepalived_vrrp[15258]: VRRP_Instance(VI_1) removing protocol VIPs.
Jan 17 16:34:50 proxy2 Keepalived_healthcheckers[15257]: Netlink reflector reports IP 172.16.31.188 removed
自动进入BACKUP状态,移除VIP;

查看各节点的VIP 和IPVS规则:
MASTER节点的的VIP生成成功,IPVS规则生成:
[root@proxy keepalived]# ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 08:00:27:3b:23:60 brd ff:ff:ff:ff:ff:ff
    inet 172.16.31.52/16 brd 172.16.255.255 scope global eth0
    inet 172.16.31.188/32 scope global eth0
    inet6 fe80::a00:27ff:fe3b:2360/64 scope link 
       valid_lft forever preferred_lft forever
[root@proxy keepalived]# ipvsadm -L -n
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  172.16.31.188:0 rr persistent 50
  -> 172.16.31.50:8080            Route   1      0          0         
  -> 172.16.31.51:8080            Route   1      0          0
BACKUP节点自动降级,VIP自动移除,但是ipvs规则还是存在的,这对我们是没有影响的,没有了IP地址只有规则也是不生效的
[root@proxy2 keepalived]# ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 08:00:27:6e:bd:28 brd ff:ff:ff:ff:ff:ff
    inet 172.16.31.53/16 brd 172.16.255.255 scope global eth0
    inet6 fe80::a00:27ff:fe6e:bd28/64 scope link 
       valid_lft forever preferred_lft forever
[root@proxy2 keepalived]# ipvsadm -L -n
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  172.16.31.188:0 rr persistent 50
  -> 172.16.31.50:8080            Route   1      0          0         
  -> 172.16.31.51:8080            Route   1      0          0
7.如果后端Realserver出现故障,则LVS规则会清除相应Realserver的规则
我们将后端的tom1节点的tomcat服务停止:
[root@tom1 ~]# catalina.sh stop
Using CATALINA_BASE:   /usr/local/tomcat
Using CATALINA_HOME:   /usr/local/tomcat
Using CATALINA_TMPDIR: /usr/local/tomcat/temp
Using JRE_HOME:        /usr/java/latest
Using CLASSPATH:       /usr/local/tomcat/bin/bootstrap.jar:/usr/local/tomcat/bin/tomcat-juli.jar

观察LVS节点的启动日志:

MASTER节点:
出现连接错误,发送了邮件:
[root@proxy keepalived]# tail -f /var/log/messages 
Jan 17 16:40:39 proxy Keepalived_healthcheckers[15365]: Error connecting server [172.16.31.50]:8080.
Jan 17 16:40:39 proxy Keepalived_healthcheckers[15365]: Removing service [172.16.31.50]:8080 from VS [172.16.31.188]:0
Jan 17 16:40:39 proxy Keepalived_healthcheckers[15365]: Remote SMTP server [127.0.0.1]:25 connected.
Jan 17 16:40:39 proxy Keepalived_healthcheckers[15365]: SMTP alert successfully sent.

BACKUP节点:
出现连接错误,发送了邮件:
[root@proxy2 keepalived]# tail -f /var/log/messages 
Jan 17 16:40:42 proxy2 Keepalived_healthcheckers[15257]: Error connecting server [172.16.31.50]:8080.
Jan 17 16:40:42 proxy2 Keepalived_healthcheckers[15257]: Removing service [172.16.31.50]:8080 from VS [172.16.31.188]:0
Jan 17 16:40:42 proxy2 Keepalived_healthcheckers[15257]: Remote SMTP server [127.0.0.1]:25 connected.
Jan 17 16:40:42 proxy2 Keepalived_healthcheckers[15257]: SMTP alert successfully sent.
在到MASTER节点查看ipvs规则:
[root@proxy keepalived]# ipvsadm -L -n
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  172.16.31.188:0 rr persistent 50
  -> 172.16.31.51:8080            Route   1      0          0         
规则已经将故障的后端tomcat服务器移除,并且我们还收到了邮件;
查看邮件:
[root@proxy keepalived]# mail
Heirloom Mail version 12.4 7/29/08.  Type ? for help.
"/var/spool/mail/root": 16 messages 12 new 14 unread
略.....
 N 12 admin@stu31.com       Sat Jan 17 15:44  17/594   "[LVS_DEVEL] Realserver [172.16.31.51]:80 - DOWN"
 N 13 admin@stu31.com       Sat Jan 17 15:44  17/594   "[LVS_DEVEL] Realserver [172.16.31.50]:80 - DOWN"
 N 14 admin@stu31.com       Sat Jan 17 15:50  17/594   "[LVS_DEVEL] Realserver [172.16.31.51]:80 - DOWN"
 N 15 admin@stu31.com       Sat Jan 17 15:50  17/594   "[LVS_DEVEL] Realserver [172.16.31.50]:80 - DOWN"
 N 16 admin@stu31.com       Sat Jan 17 16:40  17/596   "[LVS_DEVEL] Realserver [172.16.31.50]:8080 - DOWN"
& 16
Message 16:
From admin@stu31.com  Sat Jan 17 16:40:39 2015
Return-Path: <admin@stu31.com>
X-Original-To: root@localhost
Delivered-To: root@localhost.stu31.com
Date: Sat, 17 Jan 2015 08:40:39 +0000
From: admin@stu31.com
Subject: [LVS_DEVEL] Realserver [172.16.31.50]:8080 - DOWN
X-Mailer: Keepalived
To: root@localhost.stu31.com
Status: R
=> CHECK failed on service : connection error <=
& quit
注:我在这里还测试了优先级相同时,LVS的主备节点的选举情况,如果优先级都是100的话,我们停止MASTER节点的keepalived服务后,VIP和IPVS规则自动转移到了BACKUP节点,但是我们将MASTER节点的keepalived服务启动后,VIP还是在 BACKUP节点上,ipvs规则会在MASTER节点上生成;

所以我们在生产环境中一定要注意优先级的设置,主节点的优先级必须比备用节点的优先级高;

至此,LVS+Keepalived实现高可用负载均衡集群已全部完成
原文:http://sohudrgon.blog.51cto.com/3088108/1605968

转载请保留固定链接: https://linuxeye.com/architecture/2141.html

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