Container Image Requirements
============================

The CloudNativePG operator for Kubernetes is designed to work with any
compatible container image of PostgreSQL that complies with the
following requirements:

PostgreSQL executables that must be in the path:

-  ``initdb``

-  ``postgres``

-  ``pg_ctl``

-  ``pg_controldata``

-  ``pg_basebackup``

Barman Cloud executables that must be in the path:

-  ``barman-cloud-backup``

-  ``barman-cloud-backup-delete``

-  ``barman-cloud-backup-list``

-  ``barman-cloud-check-wal-archive``

-  ``barman-cloud-restore``

-  ``barman-cloud-wal-archive``

-  ``barman-cloud-wal-restore``

-  PGAudit extension installed (optional - only if PGAudit is required
   in the deployed clusters)

-  Appropriate locale settings

..  Important::
   Only  `PostgreSQL versions supported by the PGDG <https://postgresql.org/>`_  are allowed.

No entry point and/or command is required in the image definition, as
CloudNativePG overrides it with its instance manager.

..  Warning::
   Application Container Images will be used by CloudNativePG in a **Primary with multiple/optional Hot Standby Servers Architecture** only.

The CloudNativePG community provides and supports `public PostgreSQL container images <https://github.com/cloudnative-pg/postgres-containers>`_ 

that work with CloudNativePG, and publishes them on `ghcr.io <https://ghcr.io/cloudnative-pg/postgresql>`_  .

Image tag requirements
----------------------

While the image name can be anything valid for Docker, the CloudNativePG
operator relies on the *image tag* to detect the Postgres major version
contained in the image.

The image tag must start with a valid PostgreSQL major version number
(e.g. 14.5 or 15) optionally followed by a dot and the patch level.

This can be followed by any character combination that is valid and
accepted in a Docker tag, preceded by a dot, an underscore, or a minus
sign.

Examples of accepted image tags:

-  ``11.1``

-  ``12.3.2.1-1``

-  ``12.4``

-  ``13``

-  ``14.5-10``

-  ``15.0``

..  Warning::
   `latest`  is not considered a valid tag for the image.