Table of Contents

• Docker PG Backup
  • Getting the image
  • Running the image
  • Specifying environment variables
    • Filename format
  • Backing up to S3 bucket
  • Mounting Configs
  • Restoring
  • Credits

Docker PG Backup

A simple docker container that runs PostgreSQL / PostGIS backups (PostGIS is not required it will backup any PG database). It is primarily intended to be used with our docker postgis docker image. By default, it will create a backup once per night (at 23h00)in a nicely ordered directory by a year / month.

• Visit our page on the docker hub at: https://registry.hub.docker.com/u/kartoza/pg-backup/
• Visit our page on GitHub at: https://github.com/kartoza/docker-pg-backup

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:$POSTGRES_MAJOR_VERSION-$POSTGIS_MAJOR_VERSION.${POSTGIS_MINOR_RELEASE}

Where the environment variables are

POSTGRES_MAJOR_VERSION=13
POSTGIS_MAJOR_VERSION=3
POSTGIS_MINOR_RELEASE=1 

We highly suggest that you use a tagged image that match the PostgreSQL image you are running i.e (kartoza/pg-backup:13-3.1 for backing up kartoza/postgis:13-3.1 DB). The latest tag may change and may not successfully back up your database.

To build the image yourself do:

git clone https://github.com/kartoza/docker-pg-backup.git
cd docker-pg-backup
./build.sh # It will build the latest version corresponding the latest PostgreSQL version

Running the image

To create a running container do:

POSTGRES_MAJOR_VERSION=13
POSTGIS_MAJOR_VERSION=3
POSTGIS_MINOR_RELEASE=1 
docker run --name "db"  -p 25432:5432 -d -t kartoza/postgis:$POSTGRES_MAJOR_VERSION-$POSTGIS_MAJOR_VERSION.${POSTGIS_MINOR_RELEASE}
docker run --name="backups"  --link db:db -v `pwd`/backups:/backups  -d kartoza/pg-backup:$POSTGRES_MAJOR_VERSION-$POSTGIS_MAJOR_VERSION.${POSTGIS_MINOR_RELEASE}

Specifying environment variables

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

• 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
• 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 for backup, e.g. gis data. 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.
• DUMP_ARGS The default dump arguments based on official PostgreSQL Dump options.
• RESTORE_ARGS Additional restore commands based on official PostgreSQL restore
• STORAGE_BACKEND The default backend is to store the backup files. It can either be FILE or S3(Example minio or amazon bucket) backends.
• DB_TABLES A boolean variable to specify if the user wants to dump the DB as individual tables. Defaults to No
• CRON_SCHEDULE specifies the cron schedule when the backup needs to run. Defaults to midnight daily.

Note To avoid interpolation issues with the env variable ${CRON_SCHEDULE} you will need to provide the variable as a quoted string i.e ${CRON_SCHEDULE}='*/1 * * * ' or ${CRON_SCHEDULE}="/1 * * * *"

Here is a more typical example using docker-composer:

Filename format

The default backup archive generated will be stored in the /backups 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=latest The backup archive would be something like

/backups/latest.gis.dmp

Backing up to S3 bucket

The script uses s3cmd for backing up files to S3 bucket.

• ACCESS_KEY_ID Access key for the bucket
• SECRET_ACCESS_KEY Secret Access key for the bucket
• DEFAULT_REGION Defaults to 'us-west-2'
• HOST_BASE
• HOST_BUCKET
• SSL_SECURE The determines if the S3 bucket is
• BUCKET Indicates the bucket name that will be created.

You can read more about configuration options for s3cmd

For a typical usage of this look at the docker-compose-s3.yml

Mounting Configs

The image supports mounting the following configs:

• s3cfg when backing to S3 backend
• backup-cron for any custom configuration you need to specify in the file.

An environment variable ${EXTRA_CONFIG_DIR} controls the location of the folder.

If you need to mount s3cfg file. You can run the following:

-e ${EXTRA_CONFIG_DIR}=/settings
-v /data:/settings

Where s3cfg is located in /data

Restoring

The image provides a simple restore script. 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

Note: The restore script will try to delete the TARGET_DB if it matches an existing database, so make sure you know what you are doing. Then it will create a new one and restore the content from TARGET_ARCHIVE

It is generally a good practice to restore into an empty new database and then manually drop and rename the databases.

i.e if your original database is named gis, you can restore it into a new database called gis_restore

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

docker-compose exec dbbackups /backup-scripts/restore.sh

Credits

Tim Sutton ([email protected])

Admire Nyakudya ([email protected])

Rizky Maulana ([email protected]) July 2021