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Backup Management

When using the PostgreSQL Operator, the answer to the question “do you take backups of your database” is automatically “yes!”

The PostgreSQL Operator uses the open source pgBackRest backup and restore utility that is designed for working with databases that are many terabytes in size. As described in the Provisioning section, pgBackRest is enabled by default as it permits the PostgreSQL Operator to automate some advanced as well as convenient behaviors, including:

  • Efficient provisioning of new replicas that are added to the PostgreSQL cluster
  • Preventing replicas from falling out of sync from the PostgreSQL primary by allowing them to replay old WAL logs
  • Allowing failed primaries to automatically and efficiently heal using the “delta restore” feature
  • Serving as the basis for the cluster cloning feature
  • …and of course, allowing for one to take full, differential, and incremental backups and perform full and point-in-time restores

Below is one example of how PGO manages backups with both a local storage and a Amazon S3 configuration.

PostgreSQL Operator pgBackRest Integration

The PostgreSQL Operator leverages a pgBackRest repository to facilitate the usage of the pgBackRest features in a PostgreSQL cluster. When a new PostgreSQL cluster is created, it simultaneously creates a pgBackRest repository.

You can store your pgBackRest backups in up to four different locations and using four different storage types:

  • Any Kubernetes supported storage class
  • Amazon S3 (or S3 equivalents like MinIO)
  • Google Cloud Storage (GCS)
  • Azure Blob Storage

The pgBackRest repository consists of the following Kubernetes objects:

  • A Deployment
  • A Secret that contains information that is specific to the PostgreSQL cluster that it is deployed with (e.g. SSH keys, AWS S3 keys, etc.)
  • A Service

The PostgreSQL primary is automatically configured to use the pgbackrest archive-push and push the write-ahead log (WAL) archives to the correct repository.

Backups

PGO supports three types of pgBackRest backups:

  • Full (full): A full backup of all the contents of the PostgreSQL cluster
  • Differential (diff): A backup of only the files that have changed since the last full backup
  • Incremental (incr): A backup of only the files that have changed since the last full or differential backup

Scheduling Backups

Any effective disaster recovery strategy includes having regularly scheduled backups. PGO enables this by managing a series of Kubernetes CronJobs to ensure that backups are executed at scheduled times.

Note that pgBackRest presently only supports taking one backup at a time. This may change in a future release, but for the time being we suggest that you stagger your backup times.

Please see the backup configuration tutorial for how to set up backup schedules.

Restores

The PostgreSQL Operator supports the ability to perform a full restore on a PostgreSQL cluster as well as a point-in-time-recovery. There are two types of ways to restore a cluster:

  • Restore to a new cluster
  • Restore in-place

For examples for this, please see the disaster recovery tutorial

Setting Backup Retention Policies

Unless specified, pgBackRest will keep an unlimited number of backups. You can specify backup retention using the repoN-retention- options. Please see the backup configuration tutorial for examples.

Deleting a Backup

If you delete a backup that is not set to expire, you may be unable to meet your retention requirements. If you are deleting backups to free space, it is recommended to delete your oldest backups first.

A backup can be deleted by running the pgbackrest expire command directly on the pgBackRest repository Pod or a Postgres instance.