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A cron job that will back up databases running in a docker postgres container
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README.md

Docker PG Backup

A simple docker container that runs PostGIS backups. It is intended to be used primarily with our docker postgis docker image. By default it will create a backup once per night (at 23h00)in a nicely ordered directory by year / month.

Getting the image

There are various ways to get the image onto your system:

The preferred way (but using most bandwidth for the initial image) is to get our docker trusted build like this:

docker pull kartoza/pg-backup:latest
docker pull kartoza/pg-backup:9.6
docker pull kartoza/pg-backup:9.5
docker pull kartoza/pg-backup:9.4
docker pull kartoza/pg-backup:9.3

We highly suggest that you use a tagged image (9.6 currently available) as latest may change and may not successfully back up your database. Use the same or greater version of postgis as the database you are backing up.

To build the image yourself without apt-cacher (also consumes more bandwidth since deb packages need to be refetched each time you build) do:

docker build -t kartoza/pg-backups .

If you do not wish to do a local checkout first then build directly from github.

git clone git://github.com/kartoza/docker-postgis

Run

To create a running container do:

docker run --name="backups"\
           --hostname="pg-backups" \
           --link=watchkeeper_db_1:db \
           -v backups:/backups \
           -i -d kartoza/pg-backup:9.4

In this example I used a volume into which the actual backups will be stored.

Specifying environment

You can also use the following environment variables to pass a user name and password etc for the database connection.

Note: These variable names were changed when updating to support our PG version 10 image so that the names used here are consistent with those used in the postgis v10 image.

  • POSTGRES_USER if not set, defaults to : docker
  • POSTGRES_PASS if not set, defaults to : docker
  • POSTGRES_PORT if not set, defaults to : 5432
  • POSTGRES_HOST if not set, defaults to : db
  • POSTGRES_DBNAME if not set, defaults to : gis
  • ARCHIVE_FILENAME you can use your specified filename format here, default to empty, which means it will use default filename format.
  • DBLIST a space-separated list of databases to backup, e.g. gis postgres. Default is all databases.
  • REMOVE_BEFORE remove all old backups older than specified amount of days, e.g. 30 would only keep backup files younger than 30 days. Default: no files are ever removed.

Example usage:

docker run -e POSTGRES_USER=bob -e POSTGRES_PASS=secret -link db -i -d kartoza/pg-backup

One other environment variable you may like to set is a prefix for the database dumps.

  • DUMPPREFIX if not set, defaults to : PG

Example usage:

docker run -e DUMPPREFIX=foo -link db -i -d kartoza/pg-backup

Here is a more typical example using docker-composer (formerly known as fig):

For docker-compose.yml:

db:
  image: kartoza/postgis:9.4-2.1
  volumes:
    - ./pg/postgres_data:/var/lib/postgresql
    - ./pg/setup_data:/home/setup
  environment:
    - USERNAME=docker
    - PASS=docker

dbbackup:
  image: kartoza/pg-backup:9.4
  hostname: pg-backups
  volumes:
    - ./backups:/backups
  links:
    - db:db
  environment:
    - DUMPPREFIX=PG_YOURSITE
    # These are all defaults anyway, but setting explicitly in
    # case we ever want to ever use different credentials
    - POSTGRES_USER=docker
    - POSTGRES_PASS=docker
    - POSTGRES_PORT=5432
    - POSTGRES_HOST=db
    - POSTGRES_DBNAME=gis  

Then run using:

docker-compose up -d dbbackup

Filename format

The default backup archive generated will be stored in this directory (inside the container):

/backups/$(date +%Y)/$(date +%B)/${DUMPPREFIX}_${DB}.$(date +%d-%B-%Y).dmp

As a concrete example, with DUMPPREFIX=PG and if your postgis has DB name gis. The backup archive would be something like:

/backups/2019/February/PG_gis.13-February-2019.dmp

If you specify ARCHIVE_FILENAME instead (default value is empty). The filename will be fixed according to this prefix. Let's assume ARCHIVE_FILENAME=/backups/latest The backup archive would be something like

/backups/latest.gis.dmp

Restoring

A simple restore script is provided. You need to specify some environment variables first:

  • TARGET_DB: the db name to restore
  • WITH_POSTGIS: Kartoza specific, to generate POSTGIS extension along with the restore process
  • TARGET_ARCHIVE: the full path of the archive to restore

The restore script will delete the TARGET_DB, so make sure you know what you are doing. Then it will create a new one and restore the content from TARGET_ARCHIVE

If you specify these environment variable using docker-compose.yml file, then you can execute a restore process like this:

docker-compose exec dbbackup /restore.sh

Credits

Tim Sutton (tim@kartoza.com) April 2015

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