Kubernetes custom worker builder

[yashgorana]

Description

Closes https://github.com/OpenMined/Heartbeat/issues/892

Kaniko can build and push in a single job. Since build & push are two separate Syft APIs, it becomes a bit non-trivial to have kaniko build twice... first with --no-push and then with --destination. To keep things aligned with the API-stack, this PR adds build and push as two separate steps without the need of an internal registry:

• Kaniko builds the image and saves it as a tar file on a shared volume
• Crane pushes the tar image to the provided registry (without rebuilding)

There are some tradeoffs when using crane or internal registry, hence chose this method as it's the simplest and requires the least amount of maintenance.

PS - Crane is used by Kaniko itself.

Affected Dependencies

List any dependencies that are required for this change.

How has this been tested?

• Describe the tests that you ran to verify your changes.
• Provide instructions so we can reproduce.
• List any relevant details for your test configuration.

Checklist

• I have followed the Contribution Guidelines and Code of Conduct
• I have commented my code following the OpenMined Styleguide
• I have labeled this PR with the relevant Type labels
• My changes are covered by tests

[review-notebook-app]

Check out this pull request on 

See visual diffs & provide feedback on Jupyter Notebooks.

---

Powered by ReviewNB

[rasswanth-s]

Well Done @yashgorana 🚀