Check for update in base images

[bschmalhofer]

In Docker Hub there are usually no automatic rebuilds of Images when a base images changes. But base images might change because there are security fixes. So it is interesting to be at least notified when a base image is updated.

There a several ways how to approach this. Let's try first https://github.com/marketplace/actions/docker-image-update-checker .

[bschmalhofer]

Still trying to get to a working schedule workflow. The action DockerImageUpdateChecker seems to be active, but there are no runs yet.

[bschmalhofer]

Fiddled with _.github/workflows/docker_image_updatechecker.yml so that it can be started manually. An error message should be written when the base image was updated. Let's wait until such an update occured and see how the output looks like. The last push of the Perl images were 9 days ago, so it looks like upgrades are not really frequent.

[bschmalhofer]

Also, when rebuilding an image, then dockerfile.snapshot should be used for installing the Perl modules from CPAN.

[bschmalhofer]

The Perl Image was update and the check indicated this:

TODO:

• [ ] Indicate that the base image was updated also in the list of recent actions