Haproxy+keepalived做简单的高可用（主主模式）

Haproxy：

Haproxy是一个开源的高性能的反向代理或者说是负载均衡服务软件之一，它支持双机热备、虚拟主
机、基于TCP和HTTP应用代理等功能。其配置简单，而且拥有很好的对服务器节点的健康检查功能（相当
于keepalived健康检查），当其代理的后端服务器出现故障时，Haproxy会自动的将该故障服务器摘除，
当服务器的故障恢复后Haproxy还会自动将RS服务器加入。
HAProxy提供高可用性、负载均衡以及基于TCP和HTTP应用的代理，支持虚拟主机，它是免费、快速
并且可靠的一种解决方案。HAProxy特别适用于那些负载特大的web站点，这些站点通常又需要会话保持
或七层处理。HAProxy运行在当前的硬件上，完全可以支持数以万计的并发连接。并且它的运行模式使得
它可以很简单安全的整合进您当前的架构中，同时可以保护你的web服务器不被暴露到网络上。
Haproxy 配置中分成五部分内容，分别如下：
1、global：参数是进程级的，通常是和操作系统相关。这些参数一般只设置一次，如果配置无误，
就不需要再次进行修改
2、defaults：配置默认参数，这些参数可以被用到frontend，backend，Listen组件

3、frontend：接收请求的前端虚拟节点，Frontend可以更加规则直接指定具体使用后端的backend
4、backend：后端服务集群的配置，是真实服务器，一个Backend对应一个或者多个实体服务器
5、Listen Fronted和backend的组合体

Haproxy支持两种主要代理模式：

第一个是4层tcp代理（例如：可用于邮件服务内部协议通信服务器、Mysql服务等）。Haproxy软件
的四层tcp代理应用非常优秀，配置非常简单方便，比LVS和Nginx要方便很多，因为不需要在RS端执行脚
本即可实现应用代理。说明：由于Haproxy采用的是NAT模式，数据包来去都会经过Haproxy，因此，在流
量特别大的情况下，其性能不如LVS。在一般的中小型公司，建议采用haproxy做负载均衡，而不要使用
LVS或者Nginx。
第二个是7层代理（如HTTP代理）。在4层tcp代理模式下，Haproxy仅在客户端和服务器之间双向转
发流量。但是在7层模式下Haproxy会分析应用层协议，并且能通过运行、拒绝、交换、增加、修改或者
删除请求（request）或者回应（reponse）里指定内容来控制协议。Haproxy软件的最大优点在于其7层
的根据URL请求头应用过滤的功能，一般用在LVS软件的下一层，或者像官方推荐的可以挂在硬件负载均
衡NS、F5下使用。

搭建环境（CentOS 7）

拓扑图如下：

主机	ip	角色
haproxy-1	10.0.0.11	haproxy+keepalive	vip1:10.0.0.100 vip2:10.0.0.200
haproxy-2	10.0.0.12	haproxy+keepalive
web-1	10.0.0.13	web服务器
web-2	10.0.0.13	web服务器

开始配置服务

1、先配置相关主机和相关时间同步服务器：

##关闭防火墙
systemctl stop firewalld
systemctl disable firewalld
##关闭selinux
vim /etc/selinux/config
SELINUX=disabled
##同步时间
yum install -y ntpdate
crontab -e
*/5 * * * * ntpdate cn.pool.ntp.org

2、配置web服务器

##安装apache服务
[root@web-1 ~]#yum install -y httpd
[root@web-1 ~]#echo "It is web1" >> /var/www/html/index.html
[root@web-1 ~]#systemctl restart httpd
[root@web-1 ~]#systemctl enable httpd
[root@web-2 ~]#yum install -y httpd
[root@web-2 ~]#echo "It is web2" >> /var/www/html/index.html
[root@web-2 ~]#systemctl restart httpd
[root@web-2 ~]#systemctl enable httpd

##访问web服务
[root@haproxy-1 ~]# curl 10.0.0.13
It is web1
[root@haproxy-1 ~]# curl 10.0.0.14
It is web2

3、配置haproxy和keepalive

3.1、安装haproxy

[root@haproxy-1 ~]# yum install -y haproxy
[root@haproxy-2 ~]# yum install -y haproxy

##相关配置：
global：全局配置段
进程及安全配置相关的参数
性能调整相关的参数
Debug相关的参数
proxies：代理配置段
defaults：为frontend, backend以及listen提供默认配置；
frontend：前端，相当于Nginx中的server{ ... }；
backend：后端，相当于nginx中的upstream { ...  };
listen：前后端的直接组合；

3.2、配置haproxy的日志文件
##定义日志系统相关属性

log <address> [len <length>] <facility> [max level [min level]]：
<address>：日志服务器地址；
[len <length>]：每行日志记录的最大长度；

##添加日志（haproxy.cfg）:
[root@haproxy-1 haproxy]# vim haproxy.cfg
log         127.0.0.1 local2

##修改syslog.conf：
[root@haproxy-1 haproxy]# vim /etc/rsyslog.conf
# Provides UDP syslog reception
$ModLoad imudp
$UDPServerRun 514

# Provides TCP syslog reception
$ModLoad imtcp
$InputTCPServerRun 514

local2.*         /var/log/haproxy.log

##重启两个服务即可看到日志文件：
[root@haproxy-1 ~]# systemctl restart rsyslog
[root@haproxy-1 ~]# systemctl restart haproxy
[root@haproxy-1 ~]# cd /var/log/
[root@haproxy-1 log]# ls haproxy.log
haproxy.log

##把日志文件配置同步到主机haproxy-2上
[root@haproxy-1 ~]# scp /etc/haproxy/haproxy.cfg 10.0.0.12:/etc/haproxy/haproxy.cfg
[root@haproxy-1 ~]# scp /etc/rsyslog.conf 10.0.0.12:/etc/rsyslog.conf
[root@haproxy-2 ~]# systemctl restart rsyslog
[root@haproxy-2 ~]# systemctl restart haproxy
[root@haproxy-2 log]# cd /var/log/
[root@haproxy-2 log]# ls haproxy.log
haproxy.log

3.3、配置haproxy

##修改配置文件
[root@haproxy-1 ~]# vim /etc/haproxy/haproxy.cfg
frontend  main *:80
acl url_static       path_beg       -i /static /images /javascript /stylesheets
acl url_static       path_end       -i .jpg .gif .png .css .js
use_backend static          if url_static
default_backend             app
#---------------------------------------------------------------------
# static backend for serving up images, stylesheets and such
#---------------------------------------------------------------------
backend static
balance     roundrobin
server      static 127.0.0.1:4331 check
#---------------------------------------------------------------------
# round robin balancing between the various backends
#---------------------------------------------------------------------
backend app
balance     roundrobin
server   web-1  10.0.0.13:80 check
server   web-2  10.0.0.14:80 check

##把配置文件同步到haproxy-2上去
[root@haproxy-1 ~]# scp /etc/rsyslog.conf 10.0.0.12:/etc/rsyslog.conf

##重启服务
[root@haproxy-1 ~]# systemctl restart haproxy
[root@haproxy-1 ~]# systemctl enable haproxy
[root@haproxy-2 ~]# systemctl restart haproxy
[root@haproxy-2 ~]# systemctl enable haproxy

##测试，看看能不能访问web
[root@haproxy-1 haproxy]# curl 10.0.0.11
It is web1
[root@haproxy-1 haproxy]# curl 10.0.0.11
It is web2
[root@haproxy-1 haproxy]# curl 10.0.0.11
It is web1
[root@haproxy-1 haproxy]# curl 10.0.0.11
It is web2
##现在haproxy就已经配置好了

3.4、配置keepalive
安装keepalive

[root@haproxy-1 ~]# yum install -y keepalived
[root@haproxy-2 ~]# yum install -y keepalived

配置keepalive
##主机haproxy-1的keepalive配置文件

[root@haproxy-1 ~]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived

vrrp_script check_haproxy {
script "/etc/keepalived/check_haproxy.sh"
interval 2
weight 2
}
global_defs {
notification_email {
acassen@firewall.loc
}
router_id LVS_DEVEL
}
vrrp_instance VI_1 {
state MASTER
interface ens33
virtual_router_id 50
nopreempt
priority 150
advert_int 1
authentication {
auth_type PASS
auth_pass 123456
}
virtual_ipaddress {
10.0.0.100
}
track_script {
check_haproxy
}
}
vrrp_instance VI_2 {
state BACKUP
interface ens33
virtual_router_id 51
nopreempt
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 123456
}
virtual_ipaddress {
10.0.0.200
}
track_script {
check_haproxy
}
}

##主机haproxy-2的keepalive配置文件

[root@haproxy-2 ~]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived

vrrp_script check_haproxy {
script "/etc/keepalived/check_haproxy.sh"
interval 2
weight 2
}
global_defs {
notification_email {
acassen@firewall.loc
}
router_id LVS_DEVEL
}
vrrp_instance VI_1 {
state BACKUP
interface ens33
virtual_router_id 50
nopreempt
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 123456
}
virtual_ipaddress {
10.0.0.100
}
track_script {
check_haproxy
}
}
vrrp_instance VI_2 {
state MASTER
interface ens33
virtual_router_id 51
nopreempt
priority 150
advert_int 1
authentication {
auth_type PASS
auth_pass 123456
}
virtual_ipaddress {
10.0.0.200
}
track_script {
check_haproxy
}
}

##haproxy检测脚本

[root@haproxy-1 ~]# cat /etc/keepalived/check_haproxy.sh
#!/bin/bash
h=`ps -C haproxy --no-header |wc -l`
if [ $h -eq 0 ];then
systemctl stop keepalived
fi
[root@haproxy-1 ~]# chmod a+x /etc/keepalived/check_haproxy.sh
[root@haproxy-2 ~]# cat /etc/keepalived/check_haproxy.sh
#!/bin/bash
h=`ps -C haproxy --no-header |wc -l`
if [ $h -eq 0 ];then
systemctl stop keepalived
fi
[root@haproxy-2 ~]# chmod a+x /etc/keepalived/check_haproxy.sh

启动keepalive

##主机haproxy-1（由于优先级的问题，可以看到vip1在haproxy-1上）

[root@haproxy-1 ~]# systemctl restart keepalived
[root@haproxy-1 ~]# systemctl enable keepalived
[root@haproxy-1 ~]# systemctl status keepalived
● keepalived.service - LVS and VRRP High Availability Monitor
Loaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled; vendor preset: disabled)
Active: active (running) since Sat 2017-10-28 12:30:32 CST; 1s ago
Process: 2445 ExecStart=/usr/sbin/keepalived $KEEPALIVED_OPTIONS (code=exited, status=0/SUCCESS)
Main PID: 2446 (keepalived)
CGroup: /system.slice/keepalived.service
├─2446 /usr/sbin/keepalived -D
├─2447 /usr/sbin/keepalived -D
└─2448 /usr/sbin/keepalived -D
Oct 28 12:30:33 haproxy-1 Keepalived_vrrp[2448]: VRRP_Instance(VI_1) Changing effective priority from 150 to 152
Oct 28 12:30:33 haproxy-1 Keepalived_vrrp[2448]: VRRP_Instance(VI_2) Changing effective priority from 100 to 102
Oct 28 12:30:34 haproxy-1 Keepalived_vrrp[2448]: VRRP_Instance(VI_1) Entering MASTER STATE
Oct 28 12:30:34 haproxy-1 Keepalived_vrrp[2448]: VRRP_Instance(VI_1) setting protocol VIPs.
Oct 28 12:30:34 haproxy-1 Keepalived_vrrp[2448]: Sending gratuitous ARP on ens33 for 10.0.0.100
Oct 28 12:30:34 haproxy-1 Keepalived_vrrp[2448]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 for 10.0.0.100
Oct 28 12:30:34 haproxy-1 Keepalived_vrrp[2448]: Sending gratuitous ARP on ens33 for 10.0.0.100
Oct 28 12:30:34 haproxy-1 Keepalived_vrrp[2448]: Sending gratuitous ARP on ens33 for 10.0.0.100
Oct 28 12:30:34 haproxy-1 Keepalived_vrrp[2448]: Sending gratuitous ARP on ens33 for 10.0.0.100
Oct 28 12:30:34 haproxy-1 Keepalived_vrrp[2448]: Sending gratuitous ARP on ens33 for 10.0.0.100
[root@haproxy-1 ~]# ip addr
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
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:1d:7a:63 brd ff:ff:ff:ff:ff:ff
inet 10.0.0.11/24 brd 10.0.0.255 scope global ens33
valid_lft forever preferred_lft forever
inet 10.0.0.100/32 scope global ens33
valid_lft forever preferred_lft forever
inet6 fe80::8ec5:50ac:d71:20d7/64 scope link
valid_lft forever preferred_lft forever
inet6 fe80::f87c:449f:eb4a:ba03/64 scope link tentative dadfailed
valid_lft forever preferred_lft forever

##主机haproxy-2（由于优先级的问题，可以看到vip2在haproxy-2上）

[root@haproxy-2 ~]# systemctl start keepalived
[root@haproxy-2 ~]# systemctl enable keepalived
[root@haproxy-2 ~]# systemctl status keepalived
● keepalived.service - LVS and VRRP High Availability Monitor
Loaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled; vendor preset: disabled)
Active: active (running) since Sat 2017-10-28 12:30:09 CST; 5s ago
Process: 9158 ExecStart=/usr/sbin/keepalived $KEEPALIVED_OPTIONS (code=exited, status=0/SUCCESS)
Main PID: 9159 (keepalived)
CGroup: /system.slice/keepalived.service
├─9159 /usr/sbin/keepalived -D
├─9160 /usr/sbin/keepalived -D
└─9161 /usr/sbin/keepalived -D
Oct 28 12:30:10 haproxy-2 Keepalived_vrrp[9161]: VRRP_Instance(VI_1) Changing effective priority from 100 to 102
Oct 28 12:30:10 haproxy-2 Keepalived_vrrp[9161]: VRRP_Instance(VI_2) Changing effective priority from 150 to 152
Oct 28 12:30:10 haproxy-2 Keepalived_vrrp[9161]: VRRP_Instance(VI_2) Entering MASTER STATE
Oct 28 12:30:10 haproxy-2 Keepalived_vrrp[9161]: VRRP_Instance(VI_2) setting protocol VIPs.
Oct 28 12:30:10 haproxy-2 Keepalived_vrrp[9161]: Sending gratuitous ARP on ens33 for 10.0.0.200
Oct 28 12:30:10 haproxy-2 Keepalived_vrrp[9161]: VRRP_Instance(VI_2) Sending/queueing gratuitous ARPs on ens33 for 10.0.0.200
Oct 28 12:30:10 haproxy-2 Keepalived_vrrp[9161]: Sending gratuitous ARP on ens33 for 10.0.0.200
Oct 28 12:30:10 haproxy-2 Keepalived_vrrp[9161]: Sending gratuitous ARP on ens33 for 10.0.0.200
Oct 28 12:30:10 haproxy-2 Keepalived_vrrp[9161]: Sending gratuitous ARP on ens33 for 10.0.0.200
Oct 28 12:30:10 haproxy-2 Keepalived_vrrp[9161]: Sending gratuitous ARP on ens33 for 10.0.0.200
[root@haproxy-2 ~]# ip addr
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
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:76:bf:48 brd ff:ff:ff:ff:ff:ff
inet 10.0.0.12/24 brd 10.0.0.255 scope global ens33
valid_lft forever preferred_lft forever
inet 10.0.0.200/32 scope global ens33
valid_lft forever preferred_lft forever
inet6 fe80::f87c:449f:eb4a:ba03/64 scope link
valid_lft forever preferred_lft forever

访问web服务：

[root@localhost ~]# curl 10.0.0.100
It is web1
[root@localhost ~]# curl 10.0.0.100
It is web2
[root@localhost ~]# curl 10.0.0.100
It is web1
[root@localhost ~]# curl 10.0.0.100
It is web2
[root@localhost ~]#
[root@localhost ~]# curl 10.0.0.200
It is web1
[root@localhost ~]# curl 10.0.0.200
It is web2
[root@localhost ~]# curl 10.0.0.200
It is web1
[root@localhost ~]# curl 10.0.0.200
It is web2

测试

在haproxy-1上把haproxy服务给关闭掉，看看vip1会不会飘到haproxy-2上，同时也看看网页还能不能正常访问：

##在haproxy-1上关闭haproxy

[root@haproxy-1 ~]# systemctl stop haproxy
[root@haproxy-1 ~]# systemctl status haproxy
● haproxy.service - HAProxy Load Balancer
Loaded: loaded (/usr/lib/systemd/system/haproxy.service; disabled; vendor preset: disabled)
Active: inactive (dead)
Oct 28 11:30:32 haproxy-1 haproxy-systemd-wrapper[2321]: haproxy-systemd-wrapper: exit, haproxy RC=1
Oct 28 11:30:32 haproxy-1 systemd[1]: Unit haproxy.service entered failed state.
Oct 28 11:30:32 haproxy-1 systemd[1]: haproxy.service failed.
Oct 28 12:18:47 haproxy-1 systemd[1]: Started HAProxy Load Balancer.
Oct 28 12:18:47 haproxy-1 systemd[1]: Starting HAProxy Load Balancer...
Oct 28 12:18:47 haproxy-1 haproxy-systemd-wrapper[2369]: haproxy-systemd-wrapper: executing /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid -Ds
Oct 28 12:45:34 haproxy-1 systemd[1]: Stopping HAProxy Load Balancer...
Oct 28 12:45:34 haproxy-1 haproxy-systemd-wrapper[2369]: haproxy-systemd-wrapper: SIGTERM -> 2371.
Oct 28 12:45:34 haproxy-1 systemd[1]: Stopped HAProxy Load Balancer.
Oct 28 12:45:34 haproxy-1 haproxy-systemd-wrapper[2369]: haproxy-systemd-wrapper: exit, haproxy RC=0

##查看haproxy-1的keepalive服务是否已经停掉了

[root@haproxy-1 ~]# systemctl status keepalived
● keepalived.service - LVS and VRRP High Availability Monitor
Loaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled; vendor preset: disabled)
Active: inactive (dead)
Oct 28 12:30:39 haproxy-1 Keepalived_vrrp[2448]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 for 10.0.0.100
Oct 28 12:30:39 haproxy-1 Keepalived_vrrp[2448]: Sending gratuitous ARP on ens33 for 10.0.0.100
Oct 28 12:30:39 haproxy-1 Keepalived_vrrp[2448]: Sending gratuitous ARP on ens33 for 10.0.0.100
Oct 28 12:30:39 haproxy-1 Keepalived_vrrp[2448]: Sending gratuitous ARP on ens33 for 10.0.0.100
Oct 28 12:30:39 haproxy-1 Keepalived_vrrp[2448]: Sending gratuitous ARP on ens33 for 10.0.0.100
Oct 28 12:51:06 haproxy-1 Keepalived[2446]: Stopping
Oct 28 12:51:06 haproxy-1 systemd[1]: Stopping LVS and VRRP High Availability Monitor...
Oct 28 12:51:06 haproxy-1 Keepalived_vrrp[2448]: VRRP_Instance(VI_1) sent 0 priority
Oct 28 12:51:06 haproxy-1 Keepalived_vrrp[2448]: VRRP_Instance(VI_1) removing protocol VIPs.
Oct 28 12:51:07 haproxy-1 systemd[1]: Stopped LVS and VRRP High Availability Monitor.
[root@haproxy-1 ~]# ip addr
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
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:1d:7a:63 brd ff:ff:ff:ff:ff:ff
inet 10.0.0.11/24 brd 10.0.0.255 scope global ens33
valid_lft forever preferred_lft forever
inet6 fe80::8ec5:50ac:d71:20d7/64 scope link
valid_lft forever preferred_lft forever
inet6 fe80::f87c:449f:eb4a:ba03/64 scope link tentative dadfailed
valid_lft forever preferred_lft forever

##查看haproxy-2的keepalive服务状态和ip，可以看到vip1已经成功飘到haproxy-2上了

[root@haproxy-2 ~]# systemctl status keepalived
● keepalived.service - LVS and VRRP High Availability Monitor
Loaded: loaded (/usr/lib/systemd/system/keepalived.service; disabled; vendor preset: disabled)
Active: active (running) since Sat 2017-10-28 12:30:09 CST; 21min ago
Process: 9158 ExecStart=/usr/sbin/keepalived $KEEPALIVED_OPTIONS (code=exited, status=0/SUCCESS)
Main PID: 9159 (keepalived)
CGroup: /system.slice/keepalived.service
├─9159 /usr/sbin/keepalived -D
├─9160 /usr/sbin/keepalived -D
└─9161 /usr/sbin/keepalived -D
Oct 28 12:51:07 haproxy-2 Keepalived_vrrp[9161]: Sending gratuitous ARP on ens33 for 10.0.0.100
Oct 28 12:51:07 haproxy-2 Keepalived_vrrp[9161]: Sending gratuitous ARP on ens33 for 10.0.0.100
Oct 28 12:51:07 haproxy-2 Keepalived_vrrp[9161]: Sending gratuitous ARP on ens33 for 10.0.0.100
Oct 28 12:51:07 haproxy-2 Keepalived_vrrp[9161]: Sending gratuitous ARP on ens33 for 10.0.0.100
Oct 28 12:51:12 haproxy-2 Keepalived_vrrp[9161]: Sending gratuitous ARP on ens33 for 10.0.0.100
Oct 28 12:51:12 haproxy-2 Keepalived_vrrp[9161]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 for 10.0.0.100
Oct 28 12:51:12 haproxy-2 Keepalived_vrrp[9161]: Sending gratuitous ARP on ens33 for 10.0.0.100
Oct 28 12:51:12 haproxy-2 Keepalived_vrrp[9161]: Sending gratuitous ARP on ens33 for 10.0.0.100
Oct 28 12:51:12 haproxy-2 Keepalived_vrrp[9161]: Sending gratuitous ARP on ens33 for 10.0.0.100
Oct 28 12:51:12 haproxy-2 Keepalived_vrrp[9161]: Sending gratuitous ARP on ens33 for 10.0.0.100
[root@haproxy-2 ~]# ip addr
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
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:76:bf:48 brd ff:ff:ff:ff:ff:ff
inet 10.0.0.12/24 brd 10.0.0.255 scope global ens33
valid_lft forever preferred_lft forever
inet 10.0.0.200/32 scope global ens33
valid_lft forever preferred_lft forever
inet 10.0.0.100/32 scope global ens33
valid_lft forever preferred_lft forever
inet6 fe80::f87c:449f:eb4a:ba03/64 scope link
valid_lft forever preferred_lft forever

##访问web网页（可以看到web页面还是可以正常访问的）

[root@localhost ~]# curl 10.0.0.100
It is web1
[root@localhost ~]# curl 10.0.0.100
It is web2
[root@localhost ~]# curl 10.0.0.100
It is web1
[root@localhost ~]# curl 10.0.0.100
It is web2
[root@localhost ~]# curl 10.0.0.200
It is web1
[root@localhost ~]# curl 10.0.0.200
It is web2
[root@localhost ~]# curl 10.0.0.200
It is web1
[root@localhost ~]# curl 10.0.0.200
It is web2

这次的haproxy+keepalive做简单的高可用实验就已经到此结束了。如果有写错的地方，欢迎各位大神指出来，我会去改正的。如果有写的不好的地方，请多多见谅！！！