repmgr基本配置

wanghao2979發表於2021-02-23

官方網站:

https://repmgr.org


WHAT IS REPMGR?

repmgr is an open-source tool suite for managing replication and failover in a cluster of PostgreSQL servers. It enhances PostgreSQL's built-in hot-standby capabilities with tools to set up standby servers, monitor replication, and perform administrative tasks such as failover or manual switchover operations.


repmgr has provided advanced support for PostgreSQL's built-in replication mechanisms since they were introduced in 9.0. The current repmgr series, repmgr 5, supports the latest developments in replication functionality introduced from PostgreSQL 9.3 such as cascading replication, timeline switching and base backups via the replication protocol.


OPEN SOURCE FROM 2NDQUADRANT

repmgr is developed by 2ndQuadrant, the global experts in PostgreSQL support, training, development, migration and consultancy.


repmgr is free and open-source software licensed under the GNU Public License (GPL) v3. This means you are free to use and modify repmgr as you see fit, however any modifications you make may only be distributed under the same terms. 



repmgr compatibility matrix


repmgr version Supported? Latest release      Supported PostgreSQL versions

repmgr 5.x     YES         5.0.0 (2019-10-15) 9.3, 9.4, 9.5, 9.6, 10, 11, 12

repmgr 4.x     NO         4.4 (2019-06-27)    9.3, 9.4, 9.5, 9.6, 10, 11

repmgr 3.x     NO         3.3.2 (2017-05-30) 9.3, 9.4, 9.5, 9.6

repmgr 2.x     NO         2.0.3 (2015-04-16) 9.0, 9.1, 9.2, 9.3, 9.4




我們使用 postgresql 12.4 版本,所有使用repmgr 5.x 版本


使用文件為:

https://repmgr.org/docs/5.0/index.html


環境描述:

repmgr1: 192.168.112.66 centos 7.0 postgresql 12.4

repmgr2: 192.168.112.67 centos 7.0 postgresql 12.4



1.安裝

    2.1. Requirements for installing repmgr

  

    A dedicated system user for repmgr is not required; as many repmgr and repmgrd actions require direct access to the PostgreSQL data directory, these commands should be executed by the postgres user.

    我們使用 postgres 使用者進行安裝.

    

    Important

    yum install flex libselinux-devel libxml2-devel libxslt-devel openssl-devel pam-devel readline-devel


    2.3. Installing repmgr from source


    獲取原始碼

    https://github.com/2ndQuadrant/repmgr


    2.3.3. Installation of repmgr from source

    

     ./configure

     make

     make install


    3.1. Prerequisites for setting up a basic replication cluster with repmgr

  

    If you want repmgr to copy configuration files which are located outside the PostgreSQL data directory, and/or to test switchover functionality, you will also need passwordless SSH connections between both servers, and rsync should be installed.


    兩臺機器配置一下postgres 使用者的 ssh 互信


    3.2. PostgreSQL configuration

    On the primary server, a PostgreSQL instance must be initialised and running. The following replication settings may need to be adjusted:


    max_wal_senders = 10

    max_replication_slots = 10

    wal_level = 'hot_standby'

    hot_standby = on

    archive_mode = on

    archive_command = '/bin/true'


    Tip

    Rather than editing these settings in the default postgresql.conf file, create a separate file such as postgresql.replication.conf and 

    include it from the end of the main configuration file with: include 'postgresql.replication.conf'.


    我們在主庫  repmgr1  建立 postgresql.replication.conf 檔案,將如上6個引數寫入檔案中.

    編輯 postgresql.conf 檔案,在最後一行加入   include 'postgresql.replication.conf'

    重啟主庫進行驗證:

    postgres=# show max_wal_senders;

    max_wal_senders 

    -----------------

    10

    (1 row)


    3.3. Create the repmgr user and database   

    createuser -s repmgr

    createdb repmgr -O repmgr


    3.4. Configuring authentication in pg_hba.conf

    

    local   replication     all                                     trust

    host    replication     all             127.0.0.1/32            trust

    host    replication     all             192.168.112.66/24       trust

    host    replication     all             192.168.112.67/24       trust

    local   repmgr          all                                     trust

    host    repmgr          all             127.0.0.1/32            trust

    host    repmgr          all             192.168.112.66/24       trust

    host    repmgr          all             192.168.112.67/24       trust

    

    3.6. repmgr configuration file


    Create a repmgr.conf file on the primary server. The file must contain at least the following parameters:


    node_id=1

    node_name='repmgr1'

    conninfo='host=repmgr1 user=repmgr dbname=repmgr connect_timeout=2'

    data_directory='/pgsoft/data'


    3.7. Register the primary server

    [postgres@repmgr1 data]$ repmgr -f /pgsoft/data/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



    3.8. Clone the standby server

Create a repmgr.conf file on the standby server. 


node_id=2

node_name='repmgr2'

conninfo='host=repmgr2 user=repmgr dbname=repmgr connect_timeout=2'

data_directory='/pgsoft/data'



Use the --dry-run option to check the standby can be cloned:

[postgres@repmgr2 pgsoft]$ repmgr -h repmgr1 -U repmgr -d repmgr -f /pgsoft/repmgr.conf standby clone --dry-run

NOTICE: destination directory "/pgsoft/data" provided

INFO: connecting to source node

DETAIL: connection string is: host=repmgr1 user=repmgr dbname=repmgr

DETAIL: current installation size is 31 MB

INFO: "repmgr" extension is installed in database "repmgr"

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

NOTICE: standby will attach to upstream node 1

HINT: consider using the -c/--fast-checkpoint option

INFO: all prerequisites for "standby clone" are met



If no problems are reported, the standby can then be cloned with:

[postgres@repmgr2 pgsoft]$ repmgr -h repmgr1 -U repmgr -d repmgr -f /pgsoft/repmgr.conf standby clone

NOTICE: destination directory "/pgsoft/data" provided

INFO: connecting to source node

DETAIL: connection string is: host=repmgr1 user=repmgr dbname=repmgr

DETAIL: current installation size is 31 MB

NOTICE: checking for available walsenders on the source node (2 required)

NOTICE: checking replication connections can be made to the source server (2 required)

INFO: creating directory "/pgsoft/data"...

NOTICE: starting backup (using pg_basebackup)...

HINT: this may take some time; consider using the -c/--fast-checkpoint option

INFO: executing:

  pg_basebackup -l "repmgr base backup"  -D /pgsoft/data -h repmgr1 -p 5432 -U repmgr -X stream 

NOTICE: standby clone (using pg_basebackup) complete

NOTICE: you can now start your PostgreSQL server

HINT: for example: pg_ctl -D /pgsoft/data start

HINT: after starting the server, you need to register this standby with "repmgr standby register"



   3.10. Register the standby

Register the standby server with:

[postgres@repmgr2 pgsoft]$ repmgr -f /pgsoft/repmgr.conf standby register

INFO: connecting to local node "repmgr2" (ID: 2)

INFO: connecting to primary database

WARNING: --upstream-node-id not supplied, assuming upstream node is primary (node ID 1)

INFO: standby registration complete

NOTICE: standby node "repmgr2" (ID: 2) successfully registered



驗證:

[postgres@repmgr1 data]$ repmgr -f /pgsoft/data/repmgr.conf cluster show

 ID | Name    | Role    | Status    | Upstream | Location | Priority | Timeline | Connection string                                       

----+---------+---------+-----------+----------+----------+----------+----------+----------------------------------------------------------

 1  | repmgr1 | primary | * running |          | default  | 100      | 1        | host=repmgr1 user=repmgr dbname=repmgr connect_timeout=2

 2  | repmgr2 | standby |   running | repmgr1  | default  | 100      | 1        | host=repmgr2 user=repmgr dbname=repmgr connect_timeout=2




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