0. 说明
keepalived 用于高可用，
haproxy 用于负载均衡
下列中：
192.168.0.203:7480 192.168.0.202:7480 是真实网关服务节点 （RGW） 192.168.0.205 192.168.0.204 是负载均衡器 （LB） 192.168.0.200 是用于负责均衡器间的高可用的虚拟ip （VIP）
架构示意图如下：
网关高可用和负载均衡架构图
1. 环境检查及安装
yum install keepalived haproxy -y
选取两个均衡节点(均衡节点不能和rgw节点重合)，下面在均衡节点（LB）执行。
开启linux ip转发功能
echo "net.ipv4.ip_forward = 1" >> /etc/sysctl.conf
sysctl -p
允许绑定到非本地ip
echo "net.ipv4.ip_nonlocal_bind = 1" >> /etc/sysctl.conf
sysctl -p
检查 ：
/usr/sbin/sysctl net.ipv4.ip_nonlocal_bind
/usr/sbin/sysctl net.ipv4.ip_forward
cat /proc/sys/net/ipv4/ip_forward
查看是否看起了ip转发功能
如果上述文件中的值为0,说明禁止进行IP转发；如果是1,则说明IP转发功能已经打开。
2.修改keepalived + Haproxy配置文件
下面所有操作均只需在LB（负载均衡器）节点执行，
本例中即在192.168.0.204；192.168.0.205 两个节点，分别修改下面配置文件
keepalived 的配置文件
全部节点采用backup，为了减少VIP来回切换。
[root@home205 ~]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived
vrrp_script chk_haproxy {
script "killall -0 haproxy" # 检查haproxy进程
interval 2
weight 2
}
vrrp_instance VI_1 {
state BACKUP
interface eno16780032 # 似情况修改
virtual_router_id 1 # id号局域网唯一
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.0.200 # VIP，配好了，客户端连接该ip即可高可用
}
track_script {
chk_haproxy
}
}
haproxy 的配置文件
[root@home205 ~]# cat /etc/haproxy/haproxy.cfg
#---------------------------------------------------------------------
# Example configuration for a possible web application. See the
# full configuration options online.
#
# http://haproxy.1wt.eu/download/1.4/doc/configuration.txt
#
#---------------------------------------------------------------------
#---------------------------------------------------------------------
# Global settings
#---------------------------------------------------------------------
global
# to have these messages end up in /var/log/haproxy.log you will
# need to:
#
# 1) configure syslog to accept network log events. This is done
# by adding the '-r' option to the SYSLOGD_OPTIONS in
# /etc/sysconfig/syslog
#
# 2) configure local2 events to go to the /var/log/haproxy.log
# file. A line like the following can be added to
# /etc/sysconfig/syslog
#
# local2.* /var/log/haproxy.log
#
log 127.0.0.1 local2
chroot /var/lib/haproxy
pidfile /var/run/haproxy.pid
maxconn 4000
user root # 此处要修改成对应的用户，建议用root
group root
daemon
# turn on stats unix socket
stats socket /var/lib/haproxy/stats
#---------------------------------------------------------------------
# common defaults that all the 'listen' and 'backend' sections will
# use if not designated in their block
#---------------------------------------------------------------------
defaults
mode http
log global
option httplog
option dontlognull
option http-server-close
option forwardfor except 127.0.0.0/8
option redispatch
retries 3
timeout http-request 10s
timeout queue 1m
timeout connect 10s
timeout client 1m
timeout server 1m
timeout http-keep-alive 10s
timeout check 10s
maxconn 3000
#---------------------------------------------------------------------
# main frontend which proxys to the backends
#---------------------------------------------------------------------
frontend rgw *:7480 # 侦听端口
mode http
default_backend rgw
#---------------------------------------------------------------------
# round robin balancing between the various backends
#---------------------------------------------------------------------
backend rgw
mode http
balance roundrobin # 均衡模式，当前为轮循
server rgw1 192.168.0.203:7480 check # 填写真实网关IP和端口
server rgw2 192.168.0.202:7480 check
3. 启动服务
systemctl start keepalived
systemctl enable keepalived
systemctl start haproxy
systemctl enable haproxy
最后记得防火墙允许相应端口，测试环境可以直接关闭防火墙，关闭selinux。
systemctl stop firewalld
另 ： 上面演示的是搭建高可用的时候同时搭建负载均衡，如果只搭建网关高可用，则不需要配置haproxy，同时架构也有所变化，直接在两个网关节点（202， 203）安装keepalived（不需要额外节点），如下修改keepalived配置文件就可。（步骤1也转移到网关节点上操作）
[root@home202 ~]# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived
vrrp_instance VI_1 {
state BACKPUP
interface eno16780032 # 似情况修改
virtual_router_id 2 # id号局域网唯一
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.0.200 # VIP，配好了，客户端连接该ip即可高可用
}
}
重启服务
systemctl start keepalived
systemctl enable keepalived
当一个网关节点down机以后，虚拟IP会自动飘到其他网关节点。
NOTE:
相同的真实节点间可以配置多个高可用实例，设置不同的VIP，然后， 不同的节点都可以分配一个MASTER，只要不是同一个实例。（只要保证一个实例只有一个MASTER就可以）
在测试的时候发现，切换后的虚拟IP不能跨网段访问，改用物理机后验证没有发现这个问题。
