Release tooling: container registry 'reporting' utility

[ptitzler]

Is your feature request related to a problem? Please describe. Currently parts of the release process are performed manually, such as building and publishing Elyra container images on Docker Hub and quay.io:

• Docker Hub
  • https://hub.docker.com/r/elyra/kf-notebook/tags
  • https://hub.docker.com/r/elyra/elyra/tags
• quay.io
  • https://quay.io/repository/elyra/kf-notebook?tab=tags
  • https://quay.io/repository/elyra/elyra?tab=tags

We currently don't have the means to easily confirm whether the images were published as expected and that the latest tag is set to the appropriate version.

Related documentation:

• https://elyra.readthedocs.io/en/stable/getting_started/installation.html#docker
• https://elyra.readthedocs.io/en/stable/recipes/using-elyra-with-kubeflow-notebook-server.html

Describe the solution you'd like

Provide a tool that Elyra maintainers can use to answer questions such as:

• What is the container image version tag with the highest version number (x.y.z) that's published in the two container registries that the Elyra community maintains?
• Is the latest tag referencing the container image version tag with the highest version number?

[ptitzler]

@lresende @akchinSTC how about extending the create-release script with a new target?

[ptitzler]

some more background information on how this might be implemented:

• add a new target (e.g. report)
• to address the requirement raised in this issue
  • retrieve the list of container images from docker.io/elyra/elyra, docker.io/elyra/kf-notebook, quay.io/elyra/elyra, and quay.io/elyra/kfnotebook (read-only operation)
  • for each container image listed above display the tag with the greatest version identifier (e.g. elyra/elyra:3.9.0)
  • compare the checksum of the images tagged latest with the checksum of the images with the greatest version identifier and issue a warning if they are not equal (this would be an indication that the latest tag references an older version)
• (not in scope for this issue - but could be added in the future to produce a more comprehensive report)
  • report latest Elyra package versions on PyPI
  • ...