采用pacemaker+corosync实现postgresql双机热备、高可用方案

环境说明

参照上章已完成postgresql流复制配置，并关闭postgres服务。

su - postgres
pg_ctl -D /data/postgresql/data/ stop -m fast

配置集群环境

安装pacemaker和corosync

需要在所有节点执行

yum install -y pacemaker pcs psmisc policycoreutils-python postgresql-server

关闭防火墙

需要在所有节点执行

systemctl disable firewalld.service
systemctl stop firewalld.service

启用PCS

需要在所有节点执行

[root@master ~]# systemctl start pcsd.service
[root@master ~]# systemctl enable pcsd.service
Created symlink from /etc/systemd/system/multi-user.target.wants/pcsd.service to /usr/lib/systemd/system/pcsd.service.
[root@master ~]# echo hacluster |  passwd hacluster --stdin
更改用户 hacluster 的密码 。
passwd：所有的身份验证令牌已经成功更新。

集群认证

在任意机器执行，选择master执行

[root@master ~]# pcs cluster auth -u hacluster -p hacluster 192.168.174.200 192.168.174.201
192.168.174.200: Authorized
192.168.174.201: Authorized

同步设置

选择master执行

[root@master ~]# pcs cluster setup --last_man_standing=1 --name pgcluster 192.168.174.200 192.168.174.201
Destroying cluster on nodes: 192.168.174.200, 192.168.174.201...
192.168.174.200: Stopping Cluster (pacemaker)...
192.168.174.201: Stopping Cluster (pacemaker)...
192.168.174.200: Successfully destroyed cluster
192.168.174.201: Successfully destroyed cluster

Sending 'pacemaker_remote authkey' to '192.168.174.200', '192.168.174.201'
192.168.174.200: successful distribution of the file 'pacemaker_remote authkey'
192.168.174.201: successful distribution of the file 'pacemaker_remote authkey'
Sending cluster config files to the nodes...
192.168.174.200: Succeeded
192.168.174.201: Succeeded

Synchronizing pcsd certificates on nodes 192.168.174.200, 192.168.174.201...
192.168.174.200: Success
192.168.174.201: Success
Restarting pcsd on the nodes in order to reload the certificates...
192.168.174.200: Success
192.168.174.201: Success

启动集群

选择master执行

[root@master ~]# pcs cluster start --all
192.168.174.200: Starting Cluster...
192.168.174.201: Starting Cluster...

验证

验证corosync，选择在master执行

[root@master ~]# pcs status corosync

Membership information
----------------------
    Nodeid      Votes Name
         1          1 192.168.174.200 (local)
         2          1 192.168.174.201

验证pacemaker，选择在master执行

[root@master ~]# pcs status
Cluster name: pgcluster
WARNING: no stonith devices and stonith-enabled is not false
WARNING: corosync and pacemaker node names do not match (IPs used in setup?)
Stack: unknown
Current DC: NONE
Last updated: Fri Apr 13 21:24:51 2018		Last change: 

0 nodes configured
0 resources configured

No resources

Daemon Status:
  corosync: active/disabled
  pacemaker: active/disabled
  pcsd: active/enabled

配置自由切换

注意：在配置自动切换前，一定要先把master、slave1上的PostgreSQL服务停掉

选择在master执行

vim cluster_setup.sh

# 将cib配置保存到文件
pcs cluster cib pgsql_cfg
# 在pacemaker级别忽略quorum
pcs -f pgsql_cfg property set no-quorum-policy="ignore"
# 禁用STONITH
pcs -f pgsql_cfg property set stonith-enabled="false"
# 设置资源粘性，防止节点在故障恢复后发生迁移
pcs -f pgsql_cfg resource defaults resource-stickiness="INFINITY"
# 设置多少次失败后迁移
pcs -f pgsql_cfg resource defaults migration-threshold="3"
# 设置master节点虚ip
pcs -f pgsql_cfg resource create vip-master IPaddr2 ip="192.168.174.210" cidr_netmask="24"    op start   timeout="60s" interval="0s"  on-fail="restart"    op monitor timeout="60s" interval="10s" on-fail="restart"    op stop    timeout="60s" interval="0s"  on-fail="block"
# 设置slave节点虚ip
pcs -f pgsql_cfg resource create vip-slave IPaddr2 ip="192.168.174.211" cidr_netmask="24"    op start   timeout="60s" interval="0s"  on-fail="restart"    op monitor timeout="60s" interval="10s" on-fail="restart"    op stop    timeout="60s" interval="0s"  on-fail="block"
# 设置pgsql集群资源
# pgctl、psql、pgdata和config等配置根据自己的环境修改,node list填写节点的hostname，master_ip填写虚master_ip
pcs -f pgsql_cfg resource create pgsql pgsql pgctl="/usr/bin/pg_ctl" psql="/usr/bin/psql" pgdata="/var/lib/pgsql/data/" config="/var/lib/pgsql/data/postgresql.conf" rep_mode="sync" node_list="master slave1" master_ip="192.168.174.210"  repuser="replicator" primary_conninfo_opt="password=123456 keepalives_idle=60 keepalives_interval=5 keepalives_count=5" restore_command="cp /var/lib/data/pgsql/xlog_archive/%f %p" restart_on_promote='true' op start   timeout="60s" interval="0s"  on-fail="restart" op monitor timeout="60s" interval="4s" on-fail="restart" op monitor timeout="60s" interval="3s"  on-fail="restart" role="Master" op promote timeout="60s" interval="0s"  on-fail="restart" op demote  timeout="60s" interval="0s"  on-fail="stop" op stop    timeout="60s" interval="0s"  on-fail="block"
 # 设置master/slave模式，clone-max=2，两个节点
pcs -f pgsql_cfg resource master pgsql-cluster pgsql master-max=1 master-node-max=1 clone-max=2 clone-node-max=1 notify=true
# 配置master ip组
pcs -f pgsql_cfg resource group add master-group vip-master
# 配置slave ip组
pcs -f pgsql_cfg resource group add slave-group vip-slave
# 配置master ip组绑定master节点
pcs -f pgsql_cfg constraint colocation add master-group with master pgsql-cluster INFINITY
# 配置启动master节点
pcs -f pgsql_cfg constraint order promote pgsql-cluster then start master-group symmetrical=false score=INFINITY
# 配置停止master节点
pcs -f pgsql_cfg constraint order demote  pgsql-cluster then stop  master-group symmetrical=false score=0
# 配置slave ip组绑定slave节点
pcs -f pgsql_cfg constraint colocation add slave-group with slave pgsql-cluster INFINITY
# 配置启动slave节点
pcs -f pgsql_cfg constraint order promote pgsql-cluster then start slave-group symmetrical=false score=INFINITY
# 配置停止slave节点
pcs -f pgsql_cfg constraint order demote  pgsql-cluster then stop  slave-group symmetrical=false score=0
# 把配置文件push到cib
pcs cluster cib-push pgsql_cfg

注意：

# 设置pgsql集群资源

# pgctl、psql、pgdata和config等配置根据自己的环境修改,node list填写节点的hostname，master_ip填写虚master_ip

pcs -f pgsql_cfg resource create pgsql pgsql pgctl="/usr/bin/pg_ctl" psql="/usr/bin/psql" pgdata="/var/lib/pgsql/data/" config="/var/lib/pgsql/data/postgresql.conf" rep_mode="sync" node_list="master slave1" master_ip="192.168.174.210"  repuser="replicator" primary_conninfo_opt="password=123456 keepalives_idle=60 keepalives_interval=5 keepalives_count=5" restore_command="cp /var/lib/data/pgsql/xlog_archive/%f %p" restart_on_promote='true' op start   timeout="60s" interval="0s"  on-fail="restart" op monitor timeout="60s" interval="4s" on-fail="restart" op monitor timeout="60s" interval="3s"  on-fail="restart" role="Master" op promote timeout="60s" interval="0s"  on-fail="restart" op demote  timeout="60s" interval="0s"  on-fail="stop" op stop    timeout="60s" interval="0s"  on-fail="block"       

执行文件

sh cluster_setup.sh

验证

[root@master ~]# pcs status
Cluster name: pgcluster
WARNING: corosync and pacemaker node names do not match (IPs used in setup?)
Stack: corosync
Current DC: slave1 (version 1.1.16-12.el7_4.8-94ff4df) - partition with quorum
Last updated: Fri Apr 13 21:30:29 2018
Last change: Fri Apr 13 21:29:56 2018 by root via crm_attribute on master

2 nodes configured
4 resources configured

Online: [ master slave1 ]

Full list of resources:

 Master/Slave Set: pgsql-cluster [pgsql]
     Masters: [ master ]
     Slaves: [ slave1 ]
 Resource Group: master-group
     vip-master	(ocf::heartbeat:IPaddr2):	Started master
 Resource Group: slave-group
     vip-slave	(ocf::heartbeat:IPaddr2):	Started slave1

Daemon Status:
  corosync: active/disabled
  pacemaker: active/disabled
  pcsd: active/enabled

注意：当vip-master和vip-slave都是Started状态时，集群节点配置正确。否则，请检查你的配置是否有误

查看同步状态

在master查询：select * from pg_stat_replication;

#查询结果
6305	16384	replicator	slave1	192.168.174.201		60052	2018-04-13 13:29:47.76656+00	streaming	0/5000408	0/5000408	0/5000408	0/5000408	1	sync

测试故障转移

在master执行，模拟故障关闭服务

[root@master ~]# su - postgres
上一次登录：五 4月 13 22:01:13 CST 2018
-bash-4.2$ pg_ctl -D /var/lib/pgsql/data/ stop -m fast
等待服务器进程关闭 ..... 完成
服务器进程已经关闭

现master上数据库访问不通，访问slaver1上数据库可提供数据读写服务。

现向slaver1数据库插入几条数据

insert into mytab(id) values (4);
insert into mytab(id) values (5);
insert into mytab(id) values (6);

恢复服务，在master上执行

-bash-4.2$ pg_ctl -D /var/lib/pgsql/data/ start
正在启动服务器进程
-bash-4.2$ 日志:  数据库上次关闭时间为 2018-04-13 14:01:25 GMT
cp: 无法获取"/var/lib/data/pgsql/xlog_archive/00000002.history" 的文件状态(stat): 没有那个文件或目录
日志:  正在进入备用模式
cp: 无法获取"/var/lib/data/pgsql/xlog_archive/000000010000000000000006" 的文件状态(stat): 没有那个文件或目录
日志:  在0/6000080上已到达一致性恢复状态
日志:  在 0/6000080 位置有零长度的记录
cp: 无法获取"/var/lib/data/pgsql/xlog_archive/000000010000000000000006" 的文件状态(stat): 没有那个文件或目录
日志:  数据库系统准备接受只读请求的连接
cp: 无法获取"/var/lib/data/pgsql/xlog_archive/00000002.history" 的文件状态(stat): 没有那个文件或目录
日志:  流复制成功连接到主服务器
日志:  redo 在 0/6000080 开始

在master上查询：select * from mytab;发现已同步为最新数据。

在slaver1上查询：select * from pg_stat_replication;

#查询结果
58621	16384	replicator	master	192.168.174.200		52578	2018-04-13 14:02:39.701236+00	streaming	0/6000548	0/6000548	0/6000548	0/6000548	1	sync

对比两次的查询结果

--6305	16384	replicator	slave1	192.168.174.201		60052	2018-04-13 13:29:47.76656+00	streaming	0/5000408	0/5000408	0/5000408	0/5000408	1	sync
--58621	16384	replicator	master	192.168.174.200		52578	2018-04-13 14:02:39.701236+00	streaming	0/6000548	0/6000548	0/6000548	0/6000548	1	sync

发现master在模拟故障后从主机变为从机。

至此双机热备方案已全部完成！