原文地址：http://jiebaby.com/index.php/archives/7/

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。