docs: design proposal for tag and digest co-existing [ISSUE 1657]

[emalprokt]

Description

What this PR does / why we need it:

A design proposal for tag and digest to co-exist during mutation spec changes.

Proposal for the Ratify mutator to add new conditional feature to output a tag@digest image spec on top of the already existing digest.

Issue here

Which issue(s) this PR fixes (optional, using fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when the PR gets merged):

Proposes fix for #1657

Type of change

Please delete options that are not relevant.

• [ ] Bug fix (non-breaking change which fixes an issue)
• [X] New feature (non-breaking change which adds functionality)
• [X] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Helm Chart Change (any edit/addition/update that is necessary for changes merged to the main branch)
• [ ] This change requires a documentation update

Checklist:

• [ ] Does the affected code have corresponding tests?
• [ ] Are the changes documented, not just with inline documentation, but also with conceptual documentation such as an overview of a new feature, or task-based documentation like a tutorial? Consider if this change should be announced on your project blog.
• [ ] Does this introduce breaking changes that would require an announcement or bumping the major version?
• [ ] Do all new files have appropriate license header?

Post Merge Requirements

• [ ] MAINTAINERS: manually trigger the "Publish Package" workflow after merging any PR that indicates Helm Chart Change

[binbin-li]

Hi @emalprokt thanks for the proposal! We have a community meeting tomorrow at 12:00 -1:00 AM (UTC), curious if you'd like to join.

[emalprokt]

Hey @binbin-li I'd love to join the meeting! Thanks

[emalprokt]

Hi @akashsinghal @binbin-li ,

I've made changes to the proposal to have a enum style string mutationStyle instead of the previously proposed retainTag.

Everything else is as is and as discussed in the meeting.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

see 131 files with indirect coverage changes

[junczhu]

@emalprokt looks like the merge was blocked due to some commits were not signed. Would you squash all git commits into one and signing it?

[binbin-li]

@emalprokt looks like the merge was blocked due to some commits were not signed. Would you squash all git commits into one and signing it?

good catch, please follow the guide to sign the commit: https://docs.github.com/en/authentication/managing-commit-signature-verification/signing-commits

[binbin-li]

@emalprokt could you help sign previous commits or squash them so that we can merge it? thanks!

[akashsinghal]

@emalprokt just checking in to see status on this PR and if you need any help signing off the commits. Looking forward to seeing the implementation PR :)

[emalprokt]

Hi @akashsinghal @binbin-li I apologize for the long wait, I'll sign and merge this PR soon. We've moved this work to the next quarter so you'll have to wait just a little bit more for the implementation.

[binbin-li]

@emalprokt thanks for signing the commits, could you help sign off the commits to pass the DCO check as well?