Please tally an extra vote for this feature on my behalf!
For further context, I came across this thread while searching for a way to let the action user select what version of the base image to use for a Docker action. That is, it would default to the base image’s “latest” tag, but something like this step in a job would select a different version tag and build the action using that instead:
- name: Run my-action with custom base image version
And base could be passed back to the Dockerfile build via (for example):
description: 'Base Docker image version to use'
(Could also add a new field to with, but to me it makes more sense that the version would be an input.)