Provide a method to rollback the base image

[newswangerd]

We've had a few instances where changes to the base image (ghcr.io/pulp/pulp-ci-centos:latest) have caused the developer environment to break (in some cases for up to a week with the user permission changes). Developers should have the option to rollback to a previous base image when this happens so that they can continue working while a fix is created.

[mdellweg]

FWIW, if you have a tag for this image locally and do not force a pull, it should be used. So you could build your own image from a former commit of the oci images repository.

[newswangerd]

FWIW, if you have a tag for this image locally and do not force a pull, it should be used. So you could build your own image from a former commit of the oci images repository.

Until you unwittingly update the base image, and then you're in trouble, like I did :)

I was thinking we could solve this by giving users the option to customize the base image in compose.env and adding a build command that caches the previous base image. That way if an update goes sideways, you have a backup of the old image and a way to configure the env to use it.