j3asolutions/bitnami-postgres-wal-g repository overview

⁠Bitnami Postgres WAL-G

This image is largely inspired by this wal-g extension of the stock postgres image⁠. However, instead of using the stock Postgres Image⁠, it uses Bitnami's Postgres Image⁠.

In addition to gaining from all the advatanages of using a Bitnami image, this image also:

• Implements continous WAL backup using WAL-G⁠
• Includes a series of scripts that are run securely by the non-root runtime user
• Allows to configure behaviour by hooking into the container lifecycle. This is particularly useful in a Kubernetes setup.
• Can perform backup and recovery of postgres data

⁠Environment

With no extra environment variables, this image will just run in the same way as Bitnami's image. Every feature is opt-in by default.

⁠Configuring wal-g

Any environment that you pass to the container, will be picked up by wal-g. Please refer to their documentation⁠ in order to setup your S3 or S3 compatible storage for the backups.

⁠Configuring archive mode

There are two ways in which you can configure your container to run in archive mode:

• Use the usual mount volume paths of the Bitnami image
• Set ARCHIVE_MODE=true to apply a set of defaults to your configuration. The settings are:

archive_mode    = on
archive_command = 'wal-g wal-push %p'
archive_timeout = 60

⁠Full backups

Postgres physical replication requires both the physical files and a backup of WAL. Wal-g manages these two as separate processes and, in order to fully restore your data, you'll need both. By setting BACKUP_ON_INIT=true a full database backup will be performed on the first run of your container. This script will only run once and it ensures that the recovery process has a base to build on.

Every time you change the configuration of your container (e.g.: postgresql.conf, pg_hba.conf, etc.) you'll need to perform the full backup again.

⁠Recovery

In order to recover the data, you only need to run the container in an empty volume with the command /recover.

For example:

docker run --rm \
 -v <your_volume>:/bitnami/postgresql \
 -e POSTGRESQL_PASSWORD=<password> \
 -e AWS_ACCESS_KEY_ID=<key> \
 -e AWS_SECRET_ACCESS_KEY=<secret> \
 -e WALG_S3_PREFIX=s3://<bucket> \
 -e AWS_ENDPOINT=https://<minio_endpoint> \
 -e AWS_S3_FORCE_PATH_STYLE=true \
 j3asolutions/bitnami-postgres-wal-g:12.2.0-debian-10-r67-0 /recover

This command will:

• Start a new container with this image
• Recover your data using the last full backup
• Start postgres in recovery mode and restore WAL
• Destroy the container afterwards

After the container has completed, you can start your other container as you wish by mounting the data volume in it. You may even use a different image in your other container if you wish.

⁠TODO

• Allow execution of scripts during runtime (e.g.: backup)