LVS + Keepalived 高可用集群

Keepalived的设计目标是构建高可用的LVS负载均衡的集群，可以调用ipvsadm工具创建虚拟机，不仅仅用作双机热备，还可以使用keepalived构建更加方便快捷的节点，进行相关的健康检查，自动移除失效节点，恢复后再重新加入。

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，三台以上的节点服务器。此博客将以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，从而构建兼有负载均衡、高可用两种能力的LVS网站群集平台。

案例如下

使用Keepalived构建LVS群集时，也需要用到ipvsadm管理工具，但大部分工作会由Keepalived自动完成，不需要手动执行ipvsadm(除了查看和监控群集以外)。

环境分析

1)、2个调度器和2个web节点使用同一个网段地址，可以直接和外网通信。为了共享存储的安全性，一般将web节点和存储服务器规划到内网环境，所以web节点必须有两个及以上网卡的接口。

2)、我这里资源有限，也为了配置方便，所以调度器和web节点分别只有两个，在web访问请求量不大的情况下，足够了，但是若访问请求比较大，那么最少要分别配置三个调度器和web节点，如果只有两个web节点的话，访问量又比较大，那么一旦有一个宕机了，那剩下一个独苗必定会因为扛不住激增的访问请求，而被打死。

3)、准备系统映像，以便安装相关服务。

4)、自行配置防火墙策略和除了VIP之外的IP地址(我这里直接关闭了防火墙)。

5)、keepalived会自动调用IP_vs模块，所以无需手动加载。

最终效果

1)、客户端多次访问群集的VIP，得到的是同一个网页。

2)、主调度器宕机后，群集的VIP地址将会自动漂移到从(备份)调度器，此时，所有的调度任务由从调度器进行分配。当主调度器恢复运行后，群集的VIP地址会自动转移回主调度器，主调度器继续工作，从调度器转回备份状态。

3)、web节点宕机后，会被keepalived健康检查功能检测到，从而自动在web节点池中去除宕机的节点，待web节点恢复运行后，会被自动添加到web节点池中。

开始配置LVS+Keepalived高可用群集

部署第一台Web服务器

[root@centos01 ~]# yum -y install httpd  [root@centos01 ~]# echo "www.benet.com" >/var/www/html/index.html   [root@centos01 ~]# systemctl start httpd   [root@centos01 ~]# systemctl enable httpd[root@centos01 ~]# cp /etc/sysconfig/network-scripts/ifcfg-lo/etc/sysconfig/network-scripts/ifcfg-lo:0           [root@centos01 ~]# vim /etc/sysconfig/network-scripts/ifcfg-lo:0         DEVICE=lo:0   IPADDR=192.168.100.253   NETMASK=255.255.255.255   ONBOOT=yes[root@centos01 ~]# systemctl restart network   [root@centos01 ~]# ifconfig    lo: flags=73  mtu 65536        inet 127.0.0.1  netmask 255.0.0.0        inet6 ::1  prefixlen 128  scopeid 0x10        loop  txqueuelen 1  (Local Loopback)        RX packets 488  bytes 39520 (38.5 KiB)        RX errors 0  dropped 0  overruns 0  frame 0        TX packets 488  bytes 39520 (38.5 KiB)        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0lo:0: flags=73  mtu 65536        inet 192.168.100.253  netmask 255.255.255.255        loop  txqueuelen 1  (Local Loopback)[root@centos01 ~]# vim /etc/sysctl.conf net.ipv4.conf.all.arp_ignore = 1net.ipv4.conf.all.arp_announce = 2net.ipv4.conf.default.arp_ignore = 1net.ipv4.conf.default.arp_announce = 2net.ipv4.conf.lo.arp_ignore = 1net.ipv4.conf.lo.arp_announce = 2[root@centos01 ~]# sysctl -p   net.ipv4.conf.all.arp_ignore = 1net.ipv4.conf.all.arp_announce = 2net.ipv4.conf.default.arp_ignore = 1net.ipv4.conf.default.arp_announce = 2net.ipv4.conf.lo.arp_ignore = 1net.ipv4.conf.lo.arp_announce = 2

部署第二台Web服务器

[root@centos02 ~]# yum -y install httpd  [root@centos02 ~]# echo "www.accp.com" >/var/www/html/index.html   [root@centos02 ~]# systemctl start httpd  [root@centos02 ~]# systemctl enable httpd   [root@centos02 ~]# scp root@192.168.100.10:/etc/sysconfig/network-scripts/ifcfg-lo:0/etc/sysconfig/network-scripts/The authenticity of host '192.168.100.10 (192.168.100.10)' can't be established.ECDSA key fingerprint is SHA256:PUueT9fU9QbsyNB5NC5hbSXzaWxxQavBxXmfoknXl4I.ECDSA key fingerprint is MD5:6d:f7:95:0e:51:1a:d8:9e:7b:b6:3f:58:51:51:4b:3b.Are you sure you want to continue connecting (yes/no)? yes  Warning: Permanently added '192.168.100.10' (ECDSA) to the list of known hosts.root@192.168.100.10's password:   ifcfg-lo:0                                                          100%   70    53.3KB/s   00:00[root@centos02 ~]# scp root@192.168.100.10:/etc/sysctl.conf /etc/sysctl.conf            root@192.168.100.10's password:    sysctl.conf                                                         100%  660   304.3KB/s   00:00[root@centos02 ~]# systemctl restart network  [root@centos02 ~]# ifconfig    lo: flags=73  mtu 65536        inet 127.0.0.1  netmask 255.0.0.0        inet6 ::1  prefixlen 128  scopeid 0x10        loop  txqueuelen 1  (Local Loopback)        RX packets 496  bytes 40064 (39.1 KiB)        RX errors 0  dropped 0  overruns 0  frame 0        TX packets 496  bytes 40064 (39.1 KiB)        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0lo:0: flags=73  mtu 65536        inet 192.168.100.253  netmask 255.255.255.255        loop  txqueuelen 1  (Local Loopback)[root@centos02 ~]# sysctl -p  net.ipv4.conf.all.arp_ignore = 1net.ipv4.conf.all.arp_announce = 2net.ipv4.conf.default.arp_ignore = 1net.ipv4.conf.default.arp_announce = 2net.ipv4.conf.lo.arp_ignore = 1net.ipv4.conf.lo.arp_announce = 2

部署主调度器

[root@centos04 ~]# yum -y install keepalived ipvsadm [root@centos04 ~]# vim /etc/sysctl.conf             .....................net.ipv4.conf.all.send_redirects = 0net.ipv4.conf.default.send_redirects = 0net.ipv4.conf.ens33.send_redirects = 0[root@centos04 ~]# sysctl -p      net.ipv4.conf.all.send_redirects = 0net.ipv4.conf.default.send_redirects = 0net.ipv4.conf.ens33.send_redirects = 0[root@centos04 ~]# cd /etc/keepalived/[root@centos04 keepalived]# cp keepalived.conf keepalived.conf.bak          [root@centos04 keepalived]# vim keepalived.conf ! Configuration File for keepalivedglobal_defs {   router_id LVS_DEVEL1}vrrp_instance VI_1 {             state MASTER                 interface ens32                virtual_router_id 51    priority 100                advert_int 1               authentication {               auth_type PASS           auth_pass 1111           }    virtual_ipaddress {        192.168.100.253         }}virtual_server 192.168.100.253 80 {     delay_loop 6                lb_algo rr       lb_kind DR       persistence_timeout 50       protocol TCP          real_server 192.168.100.10 80 {               weight 1                         TCP_CHECK {                   connect_port 80               connect_timeout 3                 nb_get_retry 3                   delay_before_retry 3           }    }    real_server 192.168.100.20 80 {                weight 1                    TCP_CHECK {                connect_port 80                 connect_timeout 3               nb_get_retry 3                      delay_before_retry 3           }    }} [root@centos04 ~]# systemctl restart keepalived [root@centos04 ~]# systemctl enable keepalived 

配置从调度器

[root@centos05 ~]# yum -y install ipvsadm keepalived                  [root@centos05 ~]# scp root@192.168.100.40:/etc/sysctl.conf /etc/root@192.168.100.40 s password:            sysctl.conf                                 100%  566   205.8KB/s   00:00[root@centos05 ~]# sysctl -p               net.ipv4.conf.all.send_redirects = 0net.ipv4.conf.default.send_redirects = 0net.ipv4.conf.ens33.send_redirects = 0[root@centos05 ~]# scp root@192.168.100.40:/etc/keepalived/keepalived.conf/etc/keepalived/             root@192.168.100.40's password:       keepalived.conf                                                                                     100%  803     2.1MB/s   00:00[root@centos05 ~]# vim /etc/keepalived/keepalived.conf    router_id LVS_HA_Backup        state BACKUP             interface ens32    priority 99      [root@centos05 ~]# systemctl start keepalived     [root@centos05 ~]# chkconfig --level 35 keepalived on   

至此，主、从调度器也配置完成了，若需要部署多个从调度器，按照以上这个从(备份)调度器配置即可。

配置客户端访问

客户端测试访问VIP地址：192.168.100.253

为了测试，所以才在每个web节点准备不同的网页文件，以便测试是否有负载均衡的效果，现在效果已经有了，所以要搭建共享存储服务器，所有的web节点都从共享存储服务器读取网页文件向client提供，以便向client提供相同的网页文件。

接下来开始配置共享存储服务器

配置NFS服务器

[root@centos03 ~]# yum -y install rpcbind nfs-utils   [root@centos03 ~]# mkdir /web   [root@centos03 ~]# echo "www.nfs.com" > /web/index.html              [root@centos03 ~]# vim /etc/exports      /web    192.168.100.10(ro) 192.168.100.20(rw)[root@centos03 ~]# systemctl start rpcbind      [root@centos03 ~]# systemctl enable rpcbind     [root@centos03 ~]# systemctl enable nfs   [root@centos03 ~]# showmount -e 192.168.100.30   Export list for 192.168.100.30:/web 192.168.100.20,192.168.100.10

Web站点挂载共享存储目录

Web节点1服务器挂载共享目录

[root@centos01 ~]# mount 192.168.100.30:/web /var/www/html/          [root@centos01 ~]# cat /var/www/html/index.html  www.nfs.com[root@centos01 ~]# vim /etc/fstab        192.168.100.30:/web     /var/www/html/                            nfs     defaults        0 0[root@centos01 ~]# systemctl restart httpd     

Web节点2服务器挂载共享目录

[root@centos02 ~]# mount 192.168.100.30:/web /var/www/html/          [root@centos02 ~]# cat /var/www/html/index.html        www.nfs.com[root@centos02 ~]# vim /etc/fstab   192.168.100.30:/web     /var/www/html/                            nfs     defaults        0 0[root@centos02 ~]# systemctl restart httpd       

客户端再次访问测试

这次，客户端无论怎么刷新，看到的页面永远都是www.nfs.com

案例相关的查询命令

VIP在哪个调度器上，查询该调度器承载VIP地址的物理接口，即可看到VIP地址(VIP地址在备份调度器上查不到的)：

[root@centos04 ~]# ip a show dev ens32     ens32:  ate UP groupn 1000    link/ether 00:0c:29:77:2c:03 brd ff:ff:ff:ff:ff:ff    inet 192.168.100.40/24 brd 192.168.100.255 scope global noprefixroute ens32       valid_lft forever preferred_lft forever    inet 192.168.100.253/32 scope global ens32           valid_lft forever preferred_lft forever    inet6 fe80::95f8:eeb7:2ed2:d13c/64 scope link noprefixroute       valid_lft forever preferred_lft forever

查询有哪些web节点

[root@centos04 ~]# ipvsadm -ln     IP Virtual Server version 1.2.1 (size=4096)Prot LocalAddress:Port Scheduler Flags  -> RemoteAddress:Port           Forward Weight ActiveConn InActConnTCP  192.168.100.253:80 rr persistent 50  -> 192.168.100.10:80            Route   1      0          0  -> 192.168.100.20:80            Route   1      0          0

模拟第二台Web节点和主调度器故障，并在备份调度器上再次查询VIP以及web节点

[root@centos05 ~]# ip a show dev ens32   ens32:  ate UP groupn 1000    link/ether 00:0c:29:77:2c:03 brd ff:ff:ff:ff:ff:ff    inet 192.168.100.40/24 brd 192.168.100.255 scope global noprefixroute ens32       valid_lft forever preferred_lft forever    inet 192.168.100.253/32 scope global ens32           valid_lft forever preferred_lft forever    inet6 fe80::95f8:eeb7:2ed2:d13c/64 scope link noprefixroute       valid_lft forever preferred_lft forever[root@centos05 ~]# ipvsadm -ln IP Virtual Server version 1.2.1 (size=4096)Prot LocalAddress:Port Scheduler Flags  -> RemoteAddress:Port           Forward Weight ActiveConn InActConnTCP  192.168.100.253:80 rr  -> 192.168.100.10:80            Route   1      0          0

查看调度器故障切换时的日志消息

[root@centos05 ~]# tail -30 /var/log/messages