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Keepalived+LVS实现高可用负载均衡双主模式

[日期:2017-10-28] 来源:Linux社区  作者:legehappy [字体: ]

Keepalived一开始就是为lvs设计的,解决了单点服务器的故障问题,能保证服务不中断、稳定运行。(《Keepalived在前一篇文章Nginx+Keepalived实现高可用负载均衡的主从模式》 http://www.linuxidc.com/Linux/2017-10/148061.htm 就已经介绍过了,这里不多介绍了)

LVS是一种集群(Cluster)技术:采用IP负载均衡技术和基于内容请求分发技术。调度器具有很好的吞吐率,将请求均衡地转移到不同的服务器上执行,且调度器自动屏蔽掉服务器的故障,从而将一组服务器构成一个高性能的、高可用的虚拟服务器。整个服务器集群的结构对客户是透明的,而且无需修改客户端和服务器端的程序。工作在四层,在内核空间工作,基于ipvs模块,不占用流量。

双机高可用方法目前分为两种:

1)双机主从模式:即前端使用两台服务器,一台主服务器和一台热备服务器,正常情况下,主服务器绑定一个公网虚拟IP,提供负载均衡服务,热备服务器处于空闲状态;当主服务器发生故障时,热备服务器接管主服务器的公网虚拟IP,提供负载均衡服务;但是热备服务器在主机器不出现故障的时候,永远处于浪费状态,对于服务器不多的网站,该方案不经济实惠。

2)双机主主模式:这种模式的效果很强大,即前端使用两台负载均衡服务器,互为主备,且都处于活动状态(这样达到不浪费服务器),同时各自绑定一个公网虚拟IP,提供负载均衡服务;当其中一台发生故障时,另一台接管发生故障服务器的公网虚拟IP(这时由非故障机器一台负担所有的请求)。这种方案,经济实惠,非常适合于当前架构环境。

一、环境介绍:

操作系统:

[root@CentOS-4 ~]# cat /etc/RedHat-release

CentOS release 6.9 (Final)

服务器对应关系:

KA1:192.168.5.129 centos-1

KA2:192.168.5.128 centos-4

Vip1:192.168.5.200  129master/128backup

VIP2:192.168.5.210  128master/129backup

Web1:192.168.5.131 centos-2

Web2:192.168.5.132 centos-3

Client:192.168.5.140centos-5

二、环境安装:

安装依赖:

(在KA1和KA2机器上执行以下步骤)
[root@centos-4 ~]# yum -y install gcc pcre-devel zlib-devel openssl-devel

[root@centos-4~]# cd /usr/local/src/
[root@centos-4 src]# wget http://nginx.org/download/nginx-1.9.7.tar.gz

安装nginx
[root@centos-4 src]# tar -zvxfnginx-1.9.7.tar.gz 
[root@centos-4 src]# cd nginx-1.9.7

[root@centos-4 nginx-1.9.7]#./configure --prefix=/usr/local/nginx --user=nginx --group=nginx--with-http_ssl_module --with-http_flv_module --with-http_stub_status_module--with-http_gzip_static_module --with-pcre


[root@centos-4 nginx-1.9.7]# make &&make install

[root@centos-1 ~]# yum install -ykeepalived

[root@centos-1 ~]# yum install –y ipvsadm

 

      (在web1服务器和web2服务器上安装nginx)

[root@centos-2~]# yum -y install gcc pcre-devel zlib-devel openssl-devel

[root@centos-2~]# cd /usr/local/src/
[root@centos-2 src]# wget http://nginx.org/download/nginx-1.9.7.tar.gz

安装nginx
[root@centos-2 src]# tar -zvxfnginx-1.9.7.tar.gz 
[root@centos-2 src]# cd nginx-1.9.7

[root@centos-2 nginx-1.9.7]# ./configure --prefix=/usr/local/nginx --user=nginx --group=nginx--with-http_ssl_module --with-http_flv_module --with-http_stub_status_module--with-http_gzip_static_module --with-pcre


[root@centos-2 nginx-1.9.7]# make &&make install

三、配置服务:

(所以服务器上配置)

[root@centos-1 ~]# cat/etc/sysconfig/selinux

SELINUX=disabled

[root@centos-1 ~]# getenforce

Disabled

[root@centos-1 ~]# service iptables stop

1、配置keepalived:

(KA1上操作)

[root@centos-1 ~]#cat /etc/keepalived/keepalived.conf

! Configuration File forkeepalived 

 

global_defs { 

  notification_email { 

    acassen@firewall.loc 

    #failover@firewall.loc 

    #sysadmin@firewall.loc 

  } 

  router_id LVS_DEVEL 

 vrrp_script chk_http_port {       

    script "/opt/check_nginx.sh" 

    interval 2                     

    weight -5                     

    fall 2                 

    rise 1                 

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 { 

        192.168.5.200 

    } 

}

 

vrrp_instance VI_2{ 

    state BACKUP

    interface eth0

    virtual_router_id 50

    priority 90

    advert_int 1 

    authentication { 

        auth_type PASS

        auth_pass 1111 

    }

    virtual_ipaddress {

        192.168.5.210

    }

}

 

track_script {                   

  chk_http_port               

}

}

virtual_server192.168.5.200 80 {      # 定义转移ip端口80的集群服务

    delay_loop 3

    lb_algo rr

    lb_kind DR

    protocol TCP

 sorry_server 127.0.0.1 80

    real_server 192.168.5.131 80 {      # 定义集群服务包含的RS 1

        weight 1                    # 权重为1

    HTTP_GET {                  # 定义RS1的健康状态检测

        url {

          path /

          status_code 200

        }

        connect_timeout 1

        nb_get_retry 3

        delay_before_retry 1

      }

    }

    real_server 192.168.5.132 80 {      # 定义集群服务包含的RS 2

        weight 1                      # 权重为1

    HTTP_GET {                    # 定义RS2的健康状态检测

        url {

          path /

          status_code 200

        }

        connect_timeout 1

        nb_get_retry 3

        delay_before_retry 1

      }

    }

}

virtual_server 192.168.5.21080 {      # 定义转移ip端口80的集群服务

    delay_loop 3

    lb_algo rr

    lb_kind DR

    protocol TCP

 sorry_server 127.0.0.1 80

    real_server 192.168.5.131 80 {      # 定义集群服务包含的RS 1

        weight 1                    # 权重为1

    HTTP_GET {                   # 定义RS1的健康状态检测

        url {

          path /

          status_code 200

        }

        connect_timeout 1

        nb_get_retry 3

        delay_before_retry 1

      }

    }

    real_server 192.168.5.132 80 {      # 定义集群服务包含的RS 2

         weight 1                      # 权重为1

    HTTP_GET {                    # 定义RS2的健康状态检测

        url {

          path /

          status_code 200

        }

        connect_timeout 1

        nb_get_retry 3

        delay_before_retry 1

      }

    }

}

(KA2上操作)

[root@centos-2 ~]# cat/etc/keepalived/keepalived.conf

! Configuration File forkeepalived 

 

global_defs { 

  notification_email { 

    acassen@firewall.loc 

    #failover@firewall.loc 

    #sysadmin@firewall.loc 

  } 

  router_id LVS_DEVEL 

 vrrp_script chk_http_port {       

    script "/opt/check_nginx.sh" 

    interval 2                     

    weight -5                     

    fall 2                 

    rise 1                 

vrrp_instance VI_1{ 

    state BACKUP

    interface eth0 

    virtual_router_id 51 

    priority 100 

    advert_int 1 

    authentication { 

        auth_type PASS 

        auth_pass 1111 

    } 

    virtual_ipaddress { 

        192.168.5.200 

    } 

}

 

vrrp_instance VI_2{ 

    state MASTER

    interface eth0

    virtual_router_id 50

    priority 90

    advert_int 1 

    authentication { 

        auth_type PASS

        auth_pass 1111 

    }

    virtual_ipaddress {

        192.168.5.210

    }

}

 

track_script {                   

  chk_http_port               

}

}

virtual_server192.168.5.200 80 {      # 定义转移ip端口80的集群服务

    delay_loop 3

    lb_algo rr

    lb_kind DR

    protocol TCP

 sorry_server 127.0.0.1 80

    real_server 192.168.5.131 80 {      # 定义集群服务包含的RS 1

        weight 1                    # 权重为1

    HTTP_GET {                  # 定义RS1的健康状态检测

        url {

          path /

          status_code 200

        }

        connect_timeout 1

         nb_get_retry 3

        delay_before_retry 1

      }

    }

    real_server 192.168.5.132 80 {      # 定义集群服务包含的RS 2

        weight 1                      # 权重为1

    HTTP_GET {                    # 定义RS2的健康状态检测

        url {

          path /

          status_code 200

        }

        connect_timeout 1

        nb_get_retry 3

        delay_before_retry 1

      }

    }

}

virtual_server192.168.5.210 80 {      # 定义转移ip端口80的集群服务

    delay_loop 3

    lb_algo rr

    lb_kind DR

    protocol TCP

 sorry_server 127.0.0.1 80

    real_server 192.168.5.131 80 {      # 定义集群服务包含的RS 1

        weight 1                    # 权重为1

    HTTP_GET {                  # 定义RS1的健康状态检测

        url {

          path /

          status_code 200

        }

         connect_timeout 1

        nb_get_retry 3

        delay_before_retry 1

      }

    }

    real_server 192.168.5.132 80 {      # 定义集群服务包含的RS 2

        weight 1                      # 权重为1

    HTTP_GET {                    # 定义RS2的健康状态检测

        url {

           path /

          status_code 200

        }

        connect_timeout 1

        nb_get_retry 3

        delay_before_retry 1

      }

    }

}

 

编写一个监控nginx的脚本:

需要注意的是,要判断本机nginx是否正常,如果发现nginx不正常,重启之后,等待三秒在校验,任然失败则不尝试,关闭keepalived,发送邮件,其他主机此时接管VIP;

[root@centos-4~]# cat /opt/check_nginx.sh

#!/bin/bash

check=$(ps-C nginx --no-heading | wc -l)

IP=`ipadd | grep eth0 | awk  'NR==2{print $2}'| awk -F '/' '{print $1}'`

if ["${check}" = "0" ]; then

    /usr/local/nginx/sbin/nginx

    sleep 2

    counter=$(ps -C nginx --no-heading|wc -l)

    if [ "${check}" = "0"]; then

        /etc/init.d/keepalived stop

      echo "check $IP nginx is down"| mail -s "check keepalived nginx" *********@qq.com

    fi

fi

(KA1一样的监控脚本)

 

2、在后端两台web服务器上配置vip默认路由和配置两台服务器的nginx(这就不演示怎样配置nginx了。):

(考虑到方便执行就编写了一个脚本:在web1和web2服务器上配置。)

[root@centos-2 ~]# cat lvs.sh

#!/bin/bash

#realserver config vip config route arp

#legehappy

Vip1=192.168.5.200

Vip2=192.168.5.210

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

case $1 in

start)

        echo"config vip route arp" > /tmp/lvs1.txt

        /sbin/ifconfiglo:0 $Vip1 broadcast $Vip1 netmask 255.255.255.255 up

        /sbin/ifconfiglo:1 $Vip2 broadcast $Vip2 netmask 255.255.255.255 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

      routeadd -host $Vip1 dev lo:0

      routeadd -host $Vip2 dev lo:1

;;

stop)

        echo "deletevip route arp" > /tmp/lvs2.txt

       /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

      routedel -host $Vip1 dev lo:0

      routedel -host $Vip2 dev lo:1

 

;;

*)

        echo"Usage: $0 (start | stop)"

exit 1

esac

(两台后端配置web服务nginx的页面信息)

[root@centos-2 ~]# curl 192.168.5.131

10.2

[root@centos-3 ~]# curl 192.168.5.132

10.3

3、在两台前端服务器上启动keepalived服务,对于192.168.5.200的vip centos-1是master/192.168.5.210的vip centos-1是backup。

[root@centos-1 ~]#service keepalived start

[root@centos-4 ~]# service keepalived start

查看日志文件:

[root@centos-1 ~]# cat /var/log/messages

Oct 19 22:00:22 centos-1 Keepalived_vrrp[46184]: VRRP_Instance(VI_2)Sending gratuitous ARPs on eth0 for 192.168.5.210

Oct 19 22:00:22 centos-1 Keepalived_healthcheckers[46183]: Netlinkreflector reports IP 192.168.5.210 added

Oct 19 22:00:24 centos-1 Keepalived_vrrp[46184]: VRRP_Instance(VI_1)Sending gratuitous ARPs on eth0 for 192.168.5.200

Oct 19 22:00:27 centos-1 Keepalived_vrrp[46184]: VRRP_Instance(VI_2)Sending gratuitous ARPs on eth0 for 192.168.5.210

(因为KA1先启动keepalived服务所以两个vip都会在KA1上,但第二台keepaliver服务起来后vip2就会被KA2抢占回来。)

[root@centos-4 ~]# cat /var/log/messages

Oct 19 22:01:38 centos-4 Keepalived_healthcheckers[15009]: Netlinkreflector reports IP 192.168.5.210 added

Oct 19 22:01:38 centos-4 avahi-daemon[1513]: Registering new addressrecord for 192.168.5.210 on eth0.IPv4.

Oct 19 22:01:38 centos-4 Keepalived_vrrp[15010]: VRRP_Instance(VI_2)Sending gratuitous ARPs on eth0 for 192.168.5.210

Oct 19 22:01:43 centos-4 Keepalived_vrrp[15010]: VRRP_Instance(VI_2)Sending gratuitous ARPs on eth0 for 192.168.5.210

查看ip addr:

[root@centos-1 keepalived]# ip add

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdiscpfifo_fast state UP qlen 1000

    link/ether00:0c:29:0d:f3:5d brd ff:ff:ff:ff:ff:ff

    inet 192.168.5.129/24 brd192.168.5.255 scope global eth0

    inet 192.168.5.200/32scope global eth0

 

 [root@centos-4 keepalived]#ip addr

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdiscpfifo_fast state UP qlen 1000

    link/ether00:50:56:3a:84:30 brd ff:ff:ff:ff:ff:ff

    inet 192.168.5.128/24 brd192.168.5.255 scope global eth0

        inet 192.168.5.210/32 scope global eth0

(两台KA1和KA2服务器重启nginx、keepalived服务)

[root@centos-1~]# /usr/local/nginx/sbin/nginx -t

nginx:the configuration file /usr/local/nginx/conf/nginx.conf syntax is ok

nginx:configuration file /usr/local/nginx/conf/nginx.conf test is successful ###检查配置文件没问题后再执行重启nginx。

[root@centos-1~]# /usr/local/nginx/sbin/nginx -s reload

 

[root@centos-4~]# /usr/local/nginx/sbin/nginx -t

nginx:the configuration file /usr/local/nginx/conf/nginx.conf syntax is ok

nginx:configuration file /usr/local/nginx/conf/nginx.conf test is successful

[root@centos-4~]# /usr/local/nginx/sbin/nginx -s reload

[root@centos-1~]# service keepalived restart

停止keepalived:                                          [确定]

正在启动keepalived:                                      [确定]

[root@centos-4~]# service keepalived restart

停止keepalived:                                         [确定]

正在启动keepalived:                                      [确定]

 

四、测试:

验证方法(保证从负载均衡器本机到后端真实服务器之间能正常通信)

(1)、先测试完成后的效果访问vip1、vip2

Vip1:

[root@centos-5~]# curl 192.168.5.200

10.2

[root@centos-5~]# curl 192.168.5.200

10.3

[root@centos-5~]# curl 192.168.5.200

10.2

[root@centos-5~]# curl 192.168.5.200

10.3

Vip2:

[root@centos-5~]# curl 192.168.5.210

10.3

[root@centos-5~]# curl 192.168.5.210

10.2

[root@centos-5~]# curl 192.168.5.210

10.3

[root@centos-5~]# curl 192.168.5.210

10.2

 

(2)、把KA1keepalived stop掉(模拟KA1主机的keepalived故障)

[root@centos-1 ~]# service keepalived stop

停止 keepalived:

[root@centos-1 ~]# ip addr

2: eth0:<BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen1000

   link/ether 00:0c:29:0d:f3:5d brd ff:ff:ff:ff:ff:ff

   inet 192.168.5.129/24 brd 192.168.5.255 scope global eth0

   inet6 fe80::20c:29ff:fe0d:f35d/64 scope link

      valid_lft forever preferred_lft forever

(KA1主机上查看ip addr已经没有vip了。)

在KA2主机上查看日志文件

[root@centos-4 ~]# cat /var/log/messages

Oct 19 23:20:46 centos-4Keepalived_vrrp[15412]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for192.168.5.200

Oct 19 23:20:46 centos-4avahi-daemon[1513]: Registering new address record for 192.168.5.200 oneth0.IPv4.

Oct 19 23:20:46 centos-4Keepalived_healthcheckers[15411]: Netlink reflector reports IP 192.168.5.200added

Oct 19 23:20:51 centos-4Keepalived_vrrp[15412]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for192.168.5.200

(日志文件显示已经把vip:192.168.5.200接管了)

查看KA2主机的ip addr

[root@centos-4 ~]# ip addr

2: eth0:<BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen1000

   link/ether 00:50:56:3a:84:30 brd ff:ff:ff:ff:ff:ff

   inet 192.168.5.128/24 brd 192.168.5.255 scope global eth0

   inet 192.168.5.210/32 scope global eth0

   inet 192.168.5.200/32 scope global eth0

 (可以看到已经有两个vip

检查nginx服务是否被KA2接管且不中断

[root@centos-5~]# curl 192.168.5.200

10.3

[root@centos-5~]# curl 192.168.5.200

10.2

[root@centos-5~]# curl 192.168.5.210

10.3

[root@centos-5~]# curl 192.168.5.210

10.2

一些关于Keepalived相关教程集合

CentOS 7下Keepalived + HAProxy 搭建配置详解  http://www.linuxidc.com/Linux/2017-03/141593.htm

Keepalived高可用集群应用场景与配置 http://www.linuxidc.com/Linux/2017-03/141866.htm

Nginx+Keepalived实现站点高可用  http://www.linuxidc.com/Linux/2016-12/137883.htm

Nginx+Keepalived实现站点高可用(负载均衡)  http://www.linuxidc.com/Linux/2016-12/138221.htm

构建高可用集群Keepalived+Haproxy负载均衡 http://www.linuxidc.com/Linux/2016-12/138917.htm

CentOS6.5下 Keepalived高可用服务单实例配置 http://www.linuxidc.com/Linux/2016-12/138110.htm

Keepalived安装与配置 http://www.linuxidc.com/Linux/2017-02/140421.htm

Nginx之Keepalived高可用  http://www.linuxidc.com/Linux/2017-05/143708.htm

Linux下Keepalived服务安装文档  http://www.linuxidc.com/Linux/2017-03/141441.htm

本文永久更新链接地址http://www.linuxidc.com/Linux/2017-10/148060.htm

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