pacemaker+Haproxy实现集群负载均衡

高可用架构由两个核心部分组成，一个是心跳检测，判断服务器是否正常运行；一个是资源转移，用来将公共资源在正常服务器和故障服务器之间搬动

整个运行模式就是心跳检测不断的在网络中检测各个指定的设备是否能够正常响应，如果一旦发生设备故障，就由资源转移功能进行应用的切换，以继续提供服务。
corosync，心跳信息传输层，它是运行在每一个主机上的一个进程 。
Pacemaker介绍

Pacemaker是一个集群管理器。它利用推荐集群基础设施（OpenAIS
或heartbeat）提供的消息和成员能力，由辅助节点和系统进行故障检测和回收，实现性群集服务（亦称资源）的高可用性。用于资源转移。

实验环境
server1,server4:集群节点

server2,server3:后端服务器
配置Haproxy

[root@server1 haproxy]# yum install haproxy -y

[root@server1 ~]# vim /etc/haproxy/haproxy.cfg

global
    log         127.0.0.1 local2

    chroot      /var/lib/haproxy
    pidfile     /var/run/haproxy.pid
    maxconn     65535
    user        haproxy
    group       haproxy
    daemon
    stats socket /var/lib/haproxy/stats

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                 8000


frontend  main *:5000
#    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
     bind                        172.25.55.100:80
     default_backend             static

#---------------------------------------------------------------------
# static backend for serving up images, stylesheets and such
#---------------------------------------------------------------------
backend static
    balance     roundrobin
    server      static1 172.25.55.2:80        ##添加后端服务器IP
    server      static2 172.25.55.3:80

[root@server1 haproxy]# ip addr add 172.25.55.100/24 dev eth0

[root@server1 haproxy]# vim /etc/security/limits.conf 
haproxy   -       nofile  65535
[root@server1 ~]# /etc/init.d/haproxy start
Starting haproxy:

server1上Haproxy实现轮询：
测试

[root@server3 ~]# /etc/init.d/httpd start
[root@server4 ~]# /etc/init.d/httpd start

为了实现server1与server2的集群管理，将server2上与server1作相同的配置。当一个节点故障时，另一个节点会替代其进行工作。

[root@server2 ~]# yum install haproxy -y
[root@server1 haproxy]# scp /etc/haproxy/haproxy.cfg server2:/etc/haproxy/
[root@server2 ~]# ip addr add 172.25.55.100/24 dev eth0
[root@server2 ~]# /etc/init.d/haproxy start

二、配置pacemaker

Pacemaker是一个集群资源管理器。它利用集群基础构件（OpenAIS 、heartbeat或corosync）提供的消息和成员管理能力来探测并从节点或资源级别的故障中恢复，以实现群集服务（亦称资源）的最大可用性。

[root@server1 ~]# yum install pacemaker corosync -y
[root@server1 ~]# cp /etc/corosync/corosync.conf.example /etc/corosync/corosync.conf
[root@server1 haproxy]# rpm -ivh crmsh-1.2.6-0.rc2.2.1.x86_64.rpm --nodeps
[root@server1 haproxy]# scp /etc/corosync/corosync.conf server2:/etc/corosync/

[root@server1 ~]# vim /etc/corosync/corosync.conf
compatibility: whitetank

totem {
        version: 2
        secauth: off
        threads: 0
        interface {
                ringnumber: 0
                bindnetaddr: 172.25.55.0
                mcastaddr: 226.94.1.1
                mcastport: 5405
                ttl: 1
        }
}

logging {
        fileline: off
        to_stderr: no
        to_logfile: yes
        to_syslog: yes
        logfile: /var/log/cluster/corosync.log
        debug: off
        timestamp: on
        logger_subsys {
                subsys: AMF
                debug: off
        }
}

amf {
        mode: disabled
}
service{
        name:pacemaker
        ver:0
}

aisexce {
        user: root
        group: root
}

quorum {
        provider: corosync_votequorum
        expected_votes: 2
        two_node: 1
}

测试：

[root@server1 haproxy]# crm node standby
[root@server1 haproxy]# crm status
Last updated: Fri Aug  3 11:11:52 2018
Last change: Fri Aug  3 11:11:47 2018 via crm_attribute on server2
Stack: cman
Current DC: server2 - partition with quorum
Version: 1.1.10-14.el6-368c726
2 Nodes configured
0 Resources configured


Node server1: standby
Online: [ server2 ]

[root@server1 haproxy]# crm node online

[root@server2 ~]# crm node standby
[root@server2 ~]# crm status
Last updated: Fri Aug  3 11:13:11 2018
Last change: Fri Aug  3 11:13:06 2018 via crm_attribute on server2
Stack: cman
Current DC: server2 - partition with quorum
Version: 1.1.10-14.el6-368c726
2 Nodes configured
0 Resources configured


Node server2: standby
Online: [ server1 ]

[root@server1 haproxy]# crm node standby
[root@server1 haproxy]# crm status
Last updated: Fri Aug  3 11:13:43 2018
Last change: Fri Aug  3 11:13:38 2018 via crm_attribute on server2
Stack: cman
Current DC: server2 - partition with quorum
Version: 1.1.10-14.el6-368c726
2 Nodes configured
0 Resources configured


Node server1: standby
Node server2: standby