LVS+Keepalived群集

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一、 Keepalived 双机热备基础知识

        Keepalived 起初是专门针对 LVS 设计的一款强大的辅助工具，主要用来提供故障切换(Failover)和健康检査(HealthChecking)功能--判断LVS 负载调度器、节点服务器的可用性，当 master 主机出现故障及时切换到 backup 节点保证业务正常，当 master 故障主机恢复后将其重新加入群集并且业务重新切换回 master 节点。

1.1 Keepalived 概述及安装

        Keepalived 的官方网站位于 http://www.keepalived.org/，本章将以 YUM 方式讲解Keepalived 的安装、配置和使用过程。在非 LVS 群集环境中使用时，Keepalived 也可以作为热备软件使用。

1.Keepalived 的热备方式

        Keepalived 采用 VRRP(Virtual Router Redundancy Protocol，虚拟路由冗余协议)热备份协议，以软件的方式实现Linux服务器的多机热备功能。VRRP 是针对路由器的一种备份解决方案--由多台路由器组成一个热备组，通过共用的虚拟IP地址对外提供服务;每个热备组内同一时刻只有一台主路由器提供服务，其他路由器处于冗余状态。若当前在线的路由器失效，则其他路由器会自动接替(优先级决定接替顺序)虚拟 IP地址，以继续提供服务。

        热备组内的每台路由器都可能成为主路由器，虚拟路由器的IP地址(VIP)可以在热备组内的路由器之间进行转移，所以也称为漂移 IP地址。使用 Keepalived 时，漂移地址的实现不需要手动建立虚接口配置文件(如 ens33:0)，而是由Keepalived 根据配置文件自动管理。

2.Keepalived的安装与服务控制

[root@localhost ~]# systemctl stop NetworkManager
[root@localhost ~]# setenforce 0
[root@localhost ~]# systemctl stop firewalld
[root@localhost ~]# yum -y install keepalived ipvsadm
[root@localhost ~]# systemctl enable keepalived

1.2使用keepalived实现双机热备

1.主服务器的配置

[root@localhost ~]# cd /etc/keepalived/
[root@localhost keepalived]# cp keepalived.conf keepalived.conf.bak

[root@localhost keepalived]# vi keepalived.conf
global_defs {
   notification_email {
     acassen@firewall.loc
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from Alexandre.Cassen@firewall.loc
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id LVS_01
   vrrp_skip_check_adv_addr
#  vrrp_strict
   vrrp_garp_interval 0
   vrrp_gna_interval 0
}

vrrp_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 1
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.10.172
    }
}
[root@localhost keepalived]# systemctl start keepalived
[root@localhost keepalived]# ip add show dev ens33
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:ae:7f:64 brd ff:ff:ff:ff:ff:ff
    inet 192.168.10.101/24 brd 172.16.16.255 scope global ens33
       valid_lft forever preferred_lft forever
    inet 192.168.10.172/32 scope global ens33
       valid_lft forever preferred_lft forever

注释：

vrrp_strict #严格执行VRRP协议规范，此模式不支持节点单播，如果配置了此参数，vip可以漂移到这台服务器，但是ping vip不通，因此需要将此参数去掉

2.备用服务器的配置

[root@localhost ~]# systemctl stop NetworkManager
[root@localhost ~]# setenforce 0
[root@localhost ~]# systemctl stop firewalld
[root@localhost ~]# cd /etc/keepalived/
[root@localhost keepalived]# cp keepalived.conf keepalived.conf.bak

[root@localhost keepalived]# vi keepalived.conf
global_defs {
   notification_email {
     acassen@firewall.loc
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from Alexandre.Cassen@firewall.loc
   #vrrp_strict
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id LVS_02
}

vrrp_instance VI_1 {
    state BACKUP
    interface ens33
    virtual_router_id 1
    priority 99
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.10.172
    }
}

3.使用ping命令测试虚拟ip的连通性

在测试过程中down掉master服务器的网络，观察ping的结果，如果keepalive运行正常，ping的结果不会中断。

二、LVS+Keepalived高可用性

2.1配置调度器

1.主服务器keepalived的安装

[root@localhost ~]# systemctl stop NetworkManager
[root@localhost ~]# setenforce 0
[root@localhost ~]# systemctl stop firewalld
[root@localhost ~]# yum -y install keepalived ipvsadm
[root@localhost ~]# systemctl enable keepalived

2.主服务器keepalived的配置

[root@localhost ~]# cd /etc/keepalived/
[root@localhost keepalived]# cp keepalived.conf keepalived.conf.bak

[root@localhost keepalived]# vi keepalived.conf
global_defs {
   notification_email {
     acassen@firewall.loc
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from Alexandre.Cassen@firewall.loc
   #vrrp_strict
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id LVS_01
}

vrrp_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.10.172
    }
}

virtual_server 192.168.10.172 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    nat_mask 255.255.255.0
!    persistence_timeout 50
    protocol TCP

    real_server 192.168.10.103 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
    real_server 192.168.10.104 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }

}

注释：persistence_timeout 50

这个参数的意义是保持客户端的请求在这个时间段内全部发到同一个真实服务器

3.主服务器内核参数的配置

[root@localhost ~]# vi /etc/sysctl.conf
在末尾添加：
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
net.ipv4.conf.ens33.send_redirects = 0
[root@localhost ~]# sysctl -p

4.开启主服务器的keepalived服务

[root@localhost keepalived]# systemctl start keepalived
[root@localhost keepalived]# ip add show dev ens33
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:ae:7f:64 brd ff:ff:ff:ff:ff:ff
    inet 192.168.10.101/24 brd 172.16.16.255 scope global ens33
       valid_lft forever preferred_lft forever
    inet 192.168.10.172/32 scope global ens33
       valid_lft forever preferred_lft forever

2.2配置从调度器

1.从调度器keepalived安装

[root@localhost ~]# systemctl stop NetworkManager
[root@localhost ~]# setenforce 0
[root@localhost ~]# systemctl stop firewalld
[root@localhost ~]# yum -y install keepalived ipvsadm
[root@localhost ~]# systemctl enable keepalived

2.从调度器keepalived的配置

[root@localhost ~]# cd /etc/keepalived/
[root@localhost keepalived]# cp keepalived.conf keepalived.conf.bak

[root@localhost keepalived]# vi keepalived.conf
global_defs {
   notification_email {
     acassen@firewall.loc
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from Alexandre.Cassen@firewall.loc
   #vrrp_strict
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id LVS_02
}

vrrp_instance VI_1 {
    state BACKUP
    interface ens33
    virtual_router_id 51
    priority 99
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.10.172
    }
}

virtual_server 192.168.10.172 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    nat_mask 255.255.255.0
!    persistence_timeout 50
    protocol TCP

    real_server 192.168.10.101 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
    real_server 192.168.10.102 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }

}

3.从服务器内核参数的配置

[root@localhost ~]# vi /etc/sysctl.conf
在末尾添加：
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
net.ipv4.conf.ens33.send_redirects = 0
[root@localhost ~]# sysctl -p

4.开启从服务器的keepalived服务

[root@localhost keepalived]# systemctl start keepalived

2.3服务器池配置

1.web1服务器配置

（1）web1网络的配置
[root@localhost ~]# systemctl stop firewalld
[root@localhost ~]# cd /etc/sysconfig/network-scripts/
[root@localhost network-scripts]# cp ifcfg-lo ifcfg-lo:0
[root@localhost network-scripts]# vi ifcfg-lo:0
DEVICE=lo:0
IPADDR=192.168.10.172
NETMASK=255.255.255.255
ONBOOT=yes

[root@localhost network-scripts]# systemctl restrt network
[root@localhost network-scripts]# vi /etc/rc.local
/sbin/route add -host 192.168.10.172 dev lo:0

[root@localhost network-scripts]# route add -host 192.168.10.172 dev lo:0
（2）httpd服务的安装
[root@localhost ~]# yum -y install httpd
[root@localhost ~]# vi /var/www/html/index.html
test web01
（3）内核参数的设置
[root@localhost ~]# vi /etc/sysctl.conf
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
net.ipv4.conf.default.arp_ignore = 1
net.ipv4.conf.default.arp_announce = 2
net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.lo.arp_announce = 2
（4）开启httpd服务
[root@localhost ~]# systemctl start httpd

2.web2服务器配置

（1）web2网络的配置
[root@localhost ~]# systemctl stop firewalld
[root@localhost ~]# cd /etc/sysconfig/network-scripts/
[root@localhost network-scripts]# cp ifcfg-lo ifcfg-lo:0
[root@localhost network-scripts]# vi ifcfg-lo:0
DEVICE=lo:0
IPADDR=192.168.10.172
NETMASK=255.255.255.255
ONBOOT=yes

[root@localhost network-scripts]# systemctl restrt network
[root@localhost network-scripts]# vi /etc/rc.local
/sbin/route add -host 192.168.10.172 dev lo:0

[root@localhost network-scripts]# route add -host 192.168.10.172 dev lo:0
（2）httpd服务的安装
[root@localhost ~]# yum -y install httpd
[root@localhost ~]# vi /var/www/html/index.html
test web02
（3）内核参数的设置
[root@localhost ~]# vi /etc/sysctl.conf
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
net.ipv4.conf.default.arp_ignore = 1
net.ipv4.conf.default.arp_announce = 2
net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.lo.arp_announce = 2
（4）开启httpd服务
[root@localhost ~]# systemctl start httpd

2.4测试LVS+Keepalived高可用性

1.用客户端访问网站

http://192.168.10.172

刷新页面并观察网页的变化

2.在客户端使用脚本测试

[root@localhost ~]# for i in $(seq 10); do curl http://192.168.10.172  ;done

3.注意事项

（1）生产环境中可以使用NFS服务器保证网站代码的一致性，在测试环境中为了观察效果，web服务器池中的网站代码可以不一样，更加便于观察实验效果。

（2）测试计算机不要使用master调度器，在master调度器上访问VIP时，调度器不会将访问的请求调度到web服务器，而是自己尝试解析；在web服务器上测试时只能访问到自己的网页，无法实现调度。所以客户端一定要使用独立的测试计算机，或者使用处于BACKUP状态的调度器。

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