（1）本次基于VMware Workstation搭建一个四台Linux（CentOS 7.4）系统所构成的一个服务器集群，其中两台负载均衡服务器（一台为主机，另一台为备机），另外两台作为真实的Web服务器（向外部提供http服务，这里仅仅使用了CentOS默认自带的http服务，没有安装其他的类似Tomcat、Jexus服务）。
（2）本次实验基于DR负载均衡模式，设置了一个VIP（Virtual IP）为172.18.38.99，用户只需要访问这个IP地址即可获得网页服务。其中，负载均衡主机为172.18.38.100，备机为172.18.38.101。Web服务器A为172.18.38.200，Web服务器B为172.18.38.201。
实验准备
(1)，绑定静态IP地址
???[root@centos7-100 ~]# nmcli connection modify ens37 ipv4.addresses 172.18.38.100/16 ipv4.method manual connection.autoconnect yes ????[root@centos7-101 ~]# nmcli connection modify ens37 ipv4.addresses 172.18.38.101/16 ipv4.method manual connection.autoconnect yes ????[root@centos7-200 ~]# nmcli connection modify ens37 ipv4.addresses 172.18.38.200/16 ipv4.method manual connection.autoconnect yes ????[root@centos7-201 ~]# nmcli connection modify ens37 ipv4.addresses 172.18.38.201/16 ipv4.method manual connection.autoconnect yes (2)，同步时间
利用chronyd服务同步时间
1，在四台主机上都执行下面的命令，注意时间服务器必须是一台
???1，修改配置文件 ????vim /etc/chrony.conf ???????# Please consider joining the pool (http://www.pool.ntp.org/join.html). ???????server 172.18.0.1 ?iburst #指定一台服务器 ???2，利用下面这条命令概略同步一下 ?????ntpdate 172.18.0.1 ?????1 Apr 13:23:31 ntpdate[8517]: adjust time server 172.18.0.1 offset -0.350642 sec ???3，重启chrony服务 ????systemctl restart chronyd.service (3)，关闭防火墙
???systemctl disable firewalld ???systemctl stop firewalld(3)，LVS+keepalived主从配置
1，在两台lvs服务器下载keepalived
???yum ?-y install keepalived1，keepvlived_master+lvs配置文件
vim /etc/keepalived/keepalived.conf ????! Configuration File for keepalived ???global_defs { ??????notification_email { ????????root@localhost ??#出问题了发邮件给谁 ??????} ??????notification_email_from keepalived@localhost ??????smtp_server 127.0.0.1 #本机邮件服务器 ??????smtp_connect_timeout 30 #超时时间 ??????router_id proxy1 ?#服务器id ??????vrrp_mcast_group4 224.1.1.1 #多播地址所有的keepalived会在这个地址通讯，决定谁工作 ???} ???vrrp_instance VI_1 { ???????state MASTER ?#主服务器 ???????interface ens37 #网卡接口 ???????virtual_router_id 66 #服务器id ???????priority 100 ?#优先级， ???????advert_int 1 #心跳检测 1秒一次 ???????authentication { #验证 ???????????auth_type PASS ?#验证类型，基于密码 ???????????auth_pass 123456 #密码 ???????} ???????virtual_ipaddress { ???????????172.18.38.99/16 #共享IP ???????} ???} ???virtual_server 172.18.38.99 80 { ???????delay_loop 6 ?????????lb_algo rr ?#调度算法 ???????lb_kind DR ?#调度模型 ???????#persistence_timeout 50 ????????protocol TCP ????????sorry_server 127.0.0.1 80 ????????real_server 172.18.38.200 80 { ?#后端server_IP 及端口 ???????????weight 1 ?#权重 ???????????HTTP_GET { ?#健康检测方式 ???????????????url { ?????????????????path / ?????????????????status_code 200 ?????????????????} ???????????????connect_timeout 3 #超时时间 ???????????????nb_get_retry 3 #重试次数 ???????????????delay_before_retry 3 #多长时间重试 ???????????} ???????} ???????real_server 172.18.38.201 80 { ???????????weight 1 ???????????HTTP_GET { ???????????????url { ?????????????????path / ?????????????????status_code 200 ???????????????} ???????????????connect_timeout 3 ???????????????nb_get_retry 3 ???????????????delay_before_retry 3 ???????????} ???????} ???}2，keepalived_slave+lvs配置
vim /etc/keepalived/keepalived.conf ???! Configuration File for keepalived ???global_defs { ??????notification_email { ????????root@localhost ??????} ??????notification_email_from keepalived@localhost ??????smtp_server 127.0.0.1 ??????smtp_connect_timeout 30 ??????router_id proxy1 ??????vrrp_mcast_group4 224.1.1.1 ???} ???vrrp_instance VI_2 { ???????state SLAVE ?"slave关键配置" ???????interface ens37 ???????virtual_router_id 88 ???????priority 80 ???????advert_int 1 ???????authentication { ???????????auth_type PASS ???????????auth_pass 123456 ???????} ???????virtual_ipaddress { ???????????172.18.38.99/16 ???????} ???} ???virtual_server 172.18.38.99 80 { ???????delay_loop 6 ???????lb_algo rr ???????lb_kind DR ???????#persistence_timeout 50 ???????protocol TCP ???????sorry_server 127.0.0.1 80 ???????real_server 172.18.38.200 80 { ???????????weight 1 ???????????HTTP_GET { ???????????????url { ?????????????????path / ?????????????????status_code 200 ???????????????} ???????????????connect_timeout 3 ???????????????nb_get_retry 3 ???????????????delay_before_retry 3 ???????????} ???????} ???????real_server 172.18.38.201 80 { ???????????weight 1 ???????????HTTP_GET { ???????????????url { ?????????????????path / ?????????????????status_code 200 ???????????????} ???????????????connect_timeout 3 ???????????????nb_get_retry 3 ???????????????delay_before_retry 3 ???????????} ???????} ???}3，在两台lvs服务器下载ipvsadm包
???yum install ipvsadm4，在两台lvs主机上都启动keepalived服务
???systemctl start keepalived ???systemctl enable keepalived5，注意这时候会在ens37网卡上加上一个新的IP
???[root@centos7-lvs_master ~]# ip a ????????ens37: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 ???link/ether 00:50:56:39:48:cc brd ff:ff:ff:ff:ff:ff ???inet 172.18.38.101/16 brd 172.18.255.255 scope global ens37 ??????valid_lft forever preferred_lft forever ???inet 172.18.38.99/16 scope global secondary ens37 ??????valid_lft forever preferred_lft forever ???inet6 fe80::a7b9:b100:4f55:480e/64 scope link ???????valid_lft forever preferred_lft forever[root@centos7-lvs_slave ?~]# ip a ????????ens37: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 ???????????link/ether 00:50:56:39:48:cc brd ff:ff:ff:ff:ff:ff ???????????inet 172.18.38.101/16 brd 172.18.255.255 scope global ens37 ????????????????valid_lft forever preferred_lft forever ???????????inet 172.18.38.99/16 scope global secondary ens37 ????????????????valid_lft forever preferred_lft forever ???????????inet6 fe80::a7b9:b100:4f55:480e/64 scope link ?????????????????valid_lft forever preferred_lft forever5，查看调度规则
???[root@centos7-lvs_master ~]# ipvsadm -ln ???IP Virtual Server version 1.2.1 (size=4096) ???Prot LocalAddress:Port Scheduler Flags ?????-> RemoteAddress:Port ??????????Forward Weight ActiveConn InActConn ???TCP ?172.18.38.99:80 rr ?????-> 172.18.38.200:80 ????????????Route ??1 ?????0 ?????????4 ??????????????-> 172.18.38.201:80 ????????????Route ??1 ?????0 ?????????4 ???????[root@centos7-lvs_slave ?~]# ipvsadm -ln ???IP Virtual Server version 1.2.1 (size=4096) ???Prot LocalAddress:Port Scheduler Flags ?????-> RemoteAddress:Port ??????????Forward Weight ActiveConn InActConn ???TCP ?172.18.38.99:80 rr ?????-> 172.18.38.200:80 ????????????Route ??1 ?????0 ?????????0 ??????????????-> 172.18.38.201:80 ????????????Route ??1 ?????0 ?????????0 ??????(4)，配置2个后端web服务器
1，安装httpd软件
???1，安装httpd软件 ???yum install http ???2，启动服务 ???????systemctl start httpd ???????systemctl enable httpd ???2，生成web页面， ???????A主机 ???????????echo web_server_A > /var/www/html/index.html ???????b主机 ???????????echo web_server_B > /var/www/html/index.html2，在两个web服务器执行下面的脚本，会在lo网卡上生成一个vip
vim lvs_br_rs.sh ???#!/bin/bash ???#Author:wangxiaochun ???#Date:2017-08-13 ???vip=172.18.38.99 ??"只需要修改一下IP即可" ???mask=‘255.255.255.255‘ ???dev=lo:1 ???case $1 in ???start) ???????echo 1 > /proc/sys/net/ipv4/conf/all/arp_ignore ???????echo 1 > /proc/sys/net/ipv4/conf/lo/arp_ignore ???????echo 2 > /proc/sys/net/ipv4/conf/all/arp_announce ???????echo 2 > /proc/sys/net/ipv4/conf/lo/arp_announce ???????ifconfig $dev $vip netmask $mask #broadcast $vip up ???????#route add -host $vip dev $dev ???????echo "The RS Server is Ready!" ???????;; ???stop) ???????ifconfig $dev down ???????echo 0 > /proc/sys/net/ipv4/conf/all/arp_ignore ???????echo 0 > /proc/sys/net/ipv4/conf/lo/arp_ignore ???????echo 0 > /proc/sys/net/ipv4/conf/all/arp_announce ???????echo 0 > /proc/sys/net/ipv4/conf/lo/arp_announce ???????echo "The RS Server is Canceled!" ???????;; ???*) ???????echo "Usage: $(basename $0) start|stop" ???????exit 1 ???????;; ???esac3，查看lo网卡
???[root@centos7-web_server_A ~]# ip a ????1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1 ???link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 ???inet 127.0.0.1/8 scope host lo ??????valid_lft forever preferred_lft forever ???inet 172.18.38.99/32 scope global lo:1 ??????valid_lft forever preferred_lft forever ???inet6 ::1/128 scope host ???????valid_lft forever preferred_lft forever ???[root@centos7-web_server_B ~]# ip a ????1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1 ???link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 ???inet 127.0.0.1/8 scope host lo ??????valid_lft forever preferred_lft forever ???inet 172.18.38.99/32 scope global lo:1 ??????valid_lft forever preferred_lft forever ???inet6 ::1/128 scope host ???????valid_lft forever preferred_lft forever客户端测试
1，不宕任何服务
???[root@centos6 ~]# for i in {1..10};do sleep 0.5;curl 172.18.38.99;done ???web_server_B ???web_server_A ???web_server_B ???web_server_A ???web_server_B ???web_server_A ???web_server_B ???web_server_A ???web_server_B ???web_server_A2，宕掉一台keepalived测试
???[root@centos7 lvs_master ~]# systemctl stop keepalived.service ???[root@centos6 ~]# for i in {1..10};do sleep 0.5;curl 172.18.38.99;done ???web_server_B ???web_server_A ???web_server_B ???web_server_A ???web_server_B ???web_server_A ???web_server_B ???web_server_A ???web_server_B ???web_server_A测试通过
lvs+keepalived+httpd高可用集群
原文地址：http://blog.51cto.com/13598893/2093555