PostgreSQL高可用之repmgr(1主2从+1witness)+Pgpool-II实现主从切换+读写分离

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小麦苗DB宝 发表于 2022/07/06 15:30:32 2022/07/06
【摘要】 一、总体架构 二、环境申请 三、配置4台主机之间的互信 四、配置repmgr 4.1、主库修改pg_hba.conf参数文件 4.2、主库修改postgresql.conf参数文件 4.3、主库创建相关用户和数据库 4.4、4个节点分别修改repmgr.conf 4.5、在主库注册主库服务 4.6、克隆备库1和备库2 4.6.1、4个节点都配~/.pgpass密码文件 4.6.2、克隆备库...

一、总体架构

本文最终需要实现的目标:

1、1主2从流复制

2、读写分离+负载均衡(pgpool-II)

3、主从自动切换(repmgr)

所有的节点:安装操作系统、创建PG用户目录、安装PG软件、安装repmgr

主库:只初始化主库、启动主库归档

二、环境申请

先申请4台机器,6.66节点最后再申请,反正docker容器都是即开即用的。

-- 主库
docker rm -f lhrrepmgr64361
docker run -d --name lhrrepmgr64361 -h lhrrepmgr64361 \
  --net=pg-network --ip 172.72.6.61 \
  -p 64361:5432  \
  -v /sys/fs/cgroup:/sys/fs/cgroup \
  --privileged=true lhrbest/lhrpgall:1.0 \
  /usr/sbin/init

docker network connect bridge lhrrepmgr64361


-- 从库1
docker rm -f lhrrepmgr64362
docker run -d --name lhrrepmgr64362 -h lhrrepmgr64362 \
  --net=pg-network --ip 172.72.6.62 \
  -p 64362:5432  \
  -v /sys/fs/cgroup:/sys/fs/cgroup \
  --privileged=true lhrbest/lhrpgall:1.0 \
  /usr/sbin/init

docker network connect bridge lhrrepmgr64362




-- 从库2
docker rm -f lhrrepmgr64363
docker run -d --name lhrrepmgr64363 -h lhrrepmgr64363 \
  --net=pg-network --ip 172.72.6.63 \
  -p 64363:5432  \
  -v /sys/fs/cgroup:/sys/fs/cgroup \
  --privileged=true lhrbest/lhrpgall:1.0 \
  /usr/sbin/init

docker network connect bridge lhrrepmgr64363



-- Witness库
docker rm -f lhrrepmgr64364
docker run -d --name lhrrepmgr64364 -h lhrrepmgr64364 \
  --net=pg-network --ip 172.72.6.64 \
  -p 64364:5432  \
  -v /sys/fs/cgroup:/sys/fs/cgroup \
  --privileged=true lhrbest/lhrpgall:1.0 \
  /usr/sbin/init

docker network connect bridge lhrrepmgr64364



-- 重启4台机器
docker restart lhrrepmgr64361 lhrrepmgr64362 lhrrepmgr64363 lhrrepmgr64364


[root@docker35 ~]# docker ps | grep repmgr   
31d3d31c1073        lhrbest/lhrpgall:1.0                       "/usr/sbin/init"         41 hours ago        Up 41 hours         5433-5435/tcp, 0.0.0.0:64364->5432/tcp                                                               lhrrepmgr64364
572d4ea2c072        lhrbest/lhrpgall:1.0                       "/usr/sbin/init"         41 hours ago        Up 41 hours         5433-5435/tcp, 0.0.0.0:64363->5432/tcp                                                               lhrrepmgr64363
6ded416b2016        lhrbest/lhrpgall:1.0                       "/usr/sbin/init"         41 hours ago        Up 41 hours         5433-5435/tcp, 0.0.0.0:64362->5432/tcp                                                               lhrrepmgr64362
fa38b58b8f3d        lhrbest/lhrpgall:1.0                       "/usr/sbin/init"         41 hours ago        Up 41 hours         5433-5435/tcp, 0.0.0.0:64361->5432/tcp                                                               lhrrepmgr64361
[root@docker35 ~]#

👉 注意:

1、镜像lhrbest/lhrpgall:1.0中,申请的4台主机均已安装好PG 13和repmgr软件

2、PG安装方式为编译安装,数据库已初始化完成,用户为pg13

3、该镜像里已安装了PG13、PG12、PG11、PG10和PG9.6这几个版本,均为编译安装,本文使用PG13来操作

三、配置4台主机之间的互信

-- 只在主库61节点上,以root用户执行:
chmod +x sshUserSetup.sh
./sshUserSetup.sh -user pg13  -hosts "172.72.6.61 172.72.6.62 172.72.6.63 172.72.6.64" -advanced exverify -confirm

-- 在每台主机修改权限,否则报错:Bad owner or permissions on /home/pg13/.ssh/config
chmod 600 /home/pg13/.ssh/config

依次输入:yes,回车和密码即可。

脚本下载:https://share.weiyun.com/57HUxNi

验证:

ssh pg13@lhrrepmgr64361 date
ssh pg13@lhrrepmgr64362 date
ssh pg13@lhrrepmgr64363 date
ssh pg13@lhrrepmgr64364 date

第二次执行时不再提示输入yes,并且可以成功执行命令,则表示SSH对等性配置成功。

执行过程:

[pg13@lhrrepmgr64361 /]# ssh pg13@lhrrepmgr64362 date
Tue Apr 27 17:15:04 CST 2021
[root@lhrrepmgr64361 /]# 
[pg13@lhrrepmgr64361 /]# ssh pg13@lhrrepmgr64363 date
Tue Apr 27 17:15:08 CST 2021
[root@lhrrepmgr64361 /]# 
[pg13@lhrrepmgr64361 /]# ssh pg13@lhrrepmgr64364 date
Tue Apr 27 17:15:13 CST 2021
[pg13@lhrrepmgr64361 /]# 

四、配置repmgr

4.1、主库修改pg_hba.conf参数文件

-- 进入主库
docker exec -it lhrrepmgr64361 bash

su - pg13

cat >> /pg13/pgdata/pg_hba.conf <<"EOF"

local repmgr repmgr md5
host repmgr repmgr 127.0.0.1/32 md5
host repmgr repmgr 172.72.6.0/24 md5

local replication repmgr md5
host replication repmgr 127.0.0.1/32 md5
host replication repmgr 172.72.6.0/24 md5

EOF

4.2、主库修改postgresql.conf参数文件

-- 修改参数
cat >> /pg13/pgdata/postgresql.conf <<"EOF"

# 归档参数
wal_level='replica'
archive_mode='on'
archive_command='test ! -f /pg13/archive/%f && cp %p /pg13/archive/%f'
restore_command='cp /pg13/archive/%f %p'

# 主从流复制
hot_standby=on
max_wal_senders=10
wal_sender_timeout=60s
wal_keep_size=16MB

# 主从切换参数,启用PG数据库的复制槽,PG12不需要"use_replication_slots=true"这个参数了。
max_replication_slots=10
wal_log_hints=on

# 自动切换
shared_preload_libraries ='repmgr'

EOF


-- 重启
pg_ctl start

-- 查询
psql -U postgres -h 192.168.66.35 -p 64361
select * from pg_settings where name in ('wal_level','archive_mode','archive_command');


-- 切换归档
select pg_switch_wal();

4.3、主库创建相关用户和数据库

-- 创建相关用户和数据库
su - pg13
createuser -s repmgr
createdb repmgr -O repmgr

psql -h 127.0.0.1 -c "alter user repmgr with password 'lhr';"
psql -h 127.0.0.1 -c "alter user repmgr set search_path to repmgr, \"\$user\",public;"

结果:

[root@lhrrepmgr64361 /]# systemctl start pg13
[root@lhrrepmgr64361 /]# systemctl status pg13
● pg13.service - PostgreSQL database server
   Loaded: loaded (/etc/systemd/system/pg13.service; disabled; vendor preset: disabled)
   Active: active (running) since Tue 2021-04-27 16:25:24 CST; 6s ago
     Docs: man:postgres(1)
  Process: 769 ExecStart=/pg13/pg13/bin/pg_ctl start -D ${PGDATA} -s -o -p ${PGPORT} -w -t 300 (code=exited, status=0/SUCCESS)
 Main PID: 771 (postgres)
   CGroup: /docker/a777ef12d5ff83a9d47be51a98531bd45b42d2b008f7a25f894f3244ce9cc0d4/system.slice/pg13.service
           ├─771 /pg13/pg13/bin/postgres -D /pg13/pgdata -p 5432
           ├─772 postgres: logger 
           ├─774 postgres: checkpointer 
           ├─775 postgres: background writer 
           ├─776 postgres: walwriter 
           ├─777 postgres: autovacuum launcher 
           ├─778 postgres: stats collector 
           └─779 postgres: logical replication launcher 

Apr 27 16:25:23 lhrrepmgr64361 systemd[1]: Starting PostgreSQL database server...
Apr 27 16:25:24 lhrrepmgr64361 pg_ctl[769]: 2021-04-27 16:25:24.024 CST [771] LOG:  redirecting log output to logging collector process
Apr 27 16:25:24 lhrrepmgr64361 pg_ctl[769]: 2021-04-27 16:25:24.024 CST [771] HINT:  Future log output will appear in directory "pg_log".
Apr 27 16:25:24 lhrrepmgr64361 systemd[1]: Started PostgreSQL database server.

[root@lhrrepmgr64361 /]# su - pg13
Last login: Tue Apr 27 16:24:50 CST 2021 on pts/0
[pg13@lhrrepmgr64361 ~]$ 
[pg13@lhrrepmgr64361 ~]$ createuser -s repmgr
[pg13@lhrrepmgr64361 ~]$ 
[pg13@lhrrepmgr64361 ~]$ createdb repmgr -O repmgr
[pg13@lhrrepmgr64361 ~]$ 
[pg13@lhrrepmgr64361 ~]$ psql -h 127.0.0.1 -c "alter user repmgr with password 'lhr'"
ALTER ROLE
[pg13@lhrrepmgr64361 ~]$ 
[pg13@lhrrepmgr64361 ~]$ psql -h 127.0.0.1 -c "alter user repmgr set search_path to repmgr, \"\$user\",public";
ALTER ROLE


C:\Users\lhrxxt>psql -U postgres -h 192.168.66.35 -p 64361
Password for user postgres:
psql (13.2)
Type "help" for help.

postgres=# \du
                                   List of roles
 Role name |                         Attributes                         | Member of
-----------+------------------------------------------------------------+-----------
 postgres  | Superuser, Create role, Create DB, Replication, Bypass RLS | {}
 repmgr    | Superuser, Create role, Create DB                          | {}


postgres=# \l
                                 List of databases
   Name    |  Owner   | Encoding |  Collate   |   Ctype    |   Access privileges
-----------+----------+----------+------------+------------+-----------------------
 postgres  | postgres | UTF8     | en_US.utf8 | en_US.utf8 |
 repmgr    | repmgr   | UTF8     | en_US.utf8 | en_US.utf8 |
 template0 | postgres | UTF8     | en_US.utf8 | en_US.utf8 | =c/postgres          +
           |          |          |            |            | postgres=CTc/postgres
 template1 | postgres | UTF8     | en_US.utf8 | en_US.utf8 | =c/postgres          +
           |          |          |            |            | postgres=CTc/postgres
(4 rows)

4.4、4个节点分别修改repmgr.conf

-- 以pg13用户修改
su - pg13

-- 主库
cat > /pg13/pg13/repmgr.conf << "EOF"
node_id=1
node_name=lhrrepmgr64361
conninfo='host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2'
data_directory='/pg13/pgdata'
pg_bindir='/pg13/pg13/bin'
EOF


-- 从库1
cat > /pg13/pg13/repmgr.conf << "EOF"
node_id=2
node_name=lhrrepmgr64362
conninfo='host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2'
data_directory='/pg13/pgdata'
pg_bindir='/pg13/pg13/bin'
EOF

-- 从库2
cat > /pg13/pg13/repmgr.conf << "EOF"
node_id=3
node_name=lhrrepmgr64363
conninfo='host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2'
data_directory='/pg13/pgdata'
pg_bindir='/pg13/pg13/bin'
EOF


-- witness节点
cat > /pg13/pg13/repmgr.conf << "EOF"
node_id=4
node_name=lhrrepmgr64364
conninfo='host=172.72.6.64 user=repmgr password=lhr dbname=repmgr connect_timeout=2'
data_directory='/pg13/pgdata'
pg_bindir='/pg13/pg13/bin'
EOF




-- 测试
psql 'host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2'
psql 'host=172.72.6.62 user=repmgr password=lhr dbname=repmgr connect_timeout=2'
psql 'host=172.72.6.63 user=repmgr password=lhr dbname=repmgr connect_timeout=2'
psql 'host=172.72.6.64 user=repmgr password=lhr dbname=repmgr connect_timeout=2'


4.5、在主库注册主库服务

-- 注册服务
repmgr -f /pg13/pg13/repmgr.conf primary register

-- 查询
repmgr -f /pg13/pg13/repmgr.conf cluster show
psql -U repmgr -h 192.168.66.35 -p 64361 -d repmgr

执行过程:

[pg13@lhrrepmgr64361 pg13]$ repmgr -f /pg13/pg13/repmgr.conf primary register
INFO: connecting to primary database...
NOTICE: attempting to install extension "repmgr"
NOTICE: "repmgr" extension successfully installed
NOTICE: primary node record (ID: 1) registered
[pg13@lhrrepmgr64361 pg13]$ 
[pg13@lhrrepmgr64361 pg13]$ repmgr -f /pg13/pg13/repmgr.conf cluster show
 ID | Name           | Role    | Status    | Upstream | Location | Priority | Timeline | Connection string                                                        
----+----------------+---------+-----------+----------+----------+----------+----------+---------------------------------------------------------------------------
 1  | lhrrepmgr64361 | primary | * running |          | default  | 100      | 1        | host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2
 
 
C:\Users\lhrxxt>psql -U repmgr -h 192.168.66.35 -p 64361 -d repmgr
Password for user repmgr:
psql (13.2)
Type "help" for help.

repmgr=# select * from repmgr.nodes;
 node_id | upstream_node_id | active |   node_name    |  type   | location | priority |                                 conninfo                                  | repluser | slot_name |      config_file
---------+------------------+--------+----------------+---------+----------+----------+---------------------------------------------------------------------------+----------+-----------+------------------------
       1 |                  | t      | lhrrepmgr64361 | primary | default  |      100 | host=172.72.6.61 user=repmgr password=lhr dbname=repmgr connect_timeout=2 | repmgr   |           | /pg13/pg13/repmgr.conf
(1 row)

4.6、克隆备库1和备库2

4.6.1、4个节点都配~/.pgpass密码文件

su - pg13
echo "*:*:*:repmgr:lhr" > ~/.pgpass
chmod 0600 ~/.pgpass



-- 测试,若不需要密码,那就证明配置正确
psql 'host=172.72.6.61 user=repmgr dbname=repmgr connect_timeout=2'
psql 'host=172.72.6.62 user=repmgr dbname=repmgr connect_timeout=2'
psql 'host=172.72.6.63 user=repmgr dbname=repmgr connect_timeout=2'
psql 'host=172.72.6.64 user=repmgr dbname=repmgr connect_timeout=2'


4.6.2、克隆备库1

-- 其中--dry-run表示不真实执行克隆过程,只是检查是否有问题
repmgr -h 172.72.6.61 -U repmgr -d repmgr -f /pg13/pg13/repmgr.conf standby clone --force --dry-run

-- 执行克隆命令,其实还是调用pg_basebackup
repmgr -h 172.72.6.61 -U repmgr -d repmgr -f /pg13/pg13/repmgr.conf standby clone --force 


-- 启动
pg_ctl -D /pg13/pgdata start

-- 查询
psql
select * from pg_stat_wal_receiver;

执行过程:

[pg13@lhrrepmgr64362 ~]$ repmgr -h 172.72.6.61 -U repmgr -d repmgr -f /pg13/pg13/repmgr.conf standby clone --force --dry-run
NOTICE: destination directory "/pg13/pgdata" provided
INFO: connecting to source node
DETAIL: connection string is: host=172.72.6.61 user=repmgr dbname=repmgr
DETAIL: current installation size is 29 MB
INFO: "repmgr" extension is installed in database "repmgr"
WARNING: target data directory appears to be a PostgreSQL data directory
DETAIL: target data directory is "/pg13/pgdata"
HINT: use -F/--force to overwrite the existing data directory
INFO: replication slot usage not requested;  no replication slot will be set up for this standby
INFO: parameter "max_wal_senders" set to 10
NOTICE: checking for available walsenders on the source node (2 required)
INFO: sufficient walsenders available on the source node
DETAIL: 2 required, 10 available
NOTICE: checking replication connections can be made to the source server (2 required)
INFO: required number of replication connections could be made to the source server
DETAIL: 2 replication connections required
WARNING: data checksums are not enabled and "wal_log_hints" is "off"
DETAIL: pg_rewind requires "wal_log_hints" to be enabled
NOTICE: standby will attach to upstream node 1
HINT: consider using the -c/--fast-checkpoint option
INFO: all prerequisites for "standby clone" are met
[pg13@lhrrepmgr64362 ~]$ repmgrrepmgr -h 172.72.6.61 -U repmgr -d repmgr -f /pg13/pg13/repmgr.conf standby clone^C
[pg13@lhrrepmgr64362 ~]$ repmgr -h 172.72.6.61 -U repmgr -d repmgr -f /pg13/pg13/repmgr.conf standby clone
NOTICE: destination directory "/pg13/pgdata" provided
INFO: connecting to source node
DETAIL: connection string is: host=172.72.6.61 user=repmgr dbname=repmgr
DETAIL: current installation size is 29 MB
ERROR: target data directory appears to be a PostgreSQL data directory
DETAIL: target data directory is "/pg13/pgdata"
HINT: use -F/--force to overwrite the existing data directory
[pg13@lhrrepmgr64362 ~]$ repmgr -h 172.72.6.61 -U repmgr -d repmgr -f /pg13/pg13/repmgr.conf standby clone --force
NOTICE: destination directory "/pg13/pgdata" provided
INFO: connecting to source node
DETAIL: connection string is: host=172.72.6.61 user=repmgr dbname=repmgr
DETAIL: current installation size is 29 MB
INFO: replication slot usage not requested;  no replication slot will be set up for this standby
NOTICE: checking for available walsenders on the source node (2 required)
NOTICE: checking replication connections can be made to the source server (2 required)
WARNING: data checksums are not enabled and "wal_log_hints" is "off"
DETAIL: pg_rewind requires "wal_log_hints" to be enabled
WARNING: directory "/pg13/pgdata" exists but is not empty
NOTICE: -F/--force provided - deleting existing data directory "/pg13/pgdata"
NOTICE: starting backup (using pg_basebackup)...
HINT: this may take some time; consider using the -c/--fast-checkpoint option
INFO: executing:
  /pg13/pg13/bin/pg_basebackup -l "repmgr base backup"  -D /pg13/pgdata -h 172.72.6.61 -p 5432 -U repmgr -X stream 
Password: 
WARNING:  skipping special file "./.s.PGSQL.5432"
WARNING:  skipping special file "./.s.PGSQL.5432"
NOTICE: standby clone (using pg_basebackup) complete
NOTICE: you can now start your PostgreSQL server
HINT: for example: pg_ctl -D /pg13/pgdata start
HINT: after starting the server, you need to register this standby with "repmgr standby register"

[pg13@lhrrepmgr64362 ~]$ pg_ctl -D /pg13/pgdata start
waiting for server to start....2021-04-27 19:14:08.750 CST [9298] LOG:  redirecting log output to logging collector process
2021-04-27 19:14:08.750 CST [9298] HINT:  Future log output will appear in directory "pg_log".
 done
server started

[pg13@lhrrepmgr64362 ~]$ psql
psql (13.2)
Type "help" for help.


postgres=# select * from pg_stat_wal_receiver;
 pid  |  status   | receive_start_lsn | receive_start_tli | written_lsn | flushed_lsn | received_tli |      last_msg_send_time       |     last_msg_receipt_time     | latest_end_lsn |        latest_end_time        | slot_name | sender_host | sender_port |                                                                                                                                                           conninfo                                                                                                                                                            
------+-----------+-------------------+-------------------+-------------+-------------+--------------+-------------------------------+-------------------------------+----------------+-------------------------------+-----------+-------------+-------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 9304 | streaming | 0/3000000         |                 1 | 0/30001F0   | 0/30001F0   |            1 | 2021-04-27 19:15:08.862599+08 | 2021-04-27 19:15:08.862719+08 | 0/30001F0      | 2021-04-27 19:14:08.830865+08 |           | 172.72.6.61 |        5432 | user=repmgr password=******** channel_binding=disable connect_timeout=2 dbname=replication host=172.72.6.61 port=5432 application_name=lhrrepmgr64362 fallback_application_name=walreceiver sslmode=disable sslcompression=0 ssl_min_protocol_version=TLSv1.2 gssencmode=disable krbsrvname=postgres target_session_attrs=any
(1 row)

信息“NOTICE: standby clone (using pg_basebackup) complete”表示测试完成。

八、总结

1、由于主从切换需要启动数据库,所以,在整个环境中,所有的PG数据库均不能使用systemctl来管理,否则切换会出现问题。

2、若要清除节点的注册信息,也可以进入主库中,操作repmgr.nodes表信息。

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