[Umbrella Issue] Create a Image Promotion process

[dims]

Split from #153 (see that for some context)

cc @javier-b-perez @mkumatag @listx

[dims]

Notes from Nov 28th meeting

AI: @dims to follow up with Javier (current google promoter KEP)
2 issues here
storage/serving for arbitrary artifacts (including cloud-local mirrors)
Container registry for official images (including mirrors?)
AI: @bburns to contemplate registry mirroring, attestation, etc
AI: @justinsb to collab with @bburns
Undecided: do sub-projects push to one-true staging, and trust not to step on each other or push to per-sub areas?

[dims]

Related to #158

[listx]

I'm planning to OSS a proof of concept tool that understands how to reconcile a registry manifest (basically a list of images with digest/tag mappings) from a source registry to a destination registry. This should be available in January 2019. Once that tool is open sourced, I can wire up a basic promotion process for a number of images into a test registry to demonstrate how it will work.

For now the tool prototype deals with 2 registries (source vs dest, aka "staging" vs "prod"), but it is trivial to extend it to deal with more than 1 destination (so that we can have mirrors for example). After it is open sourced we can have more discussions about it in its own repository (or continue in this issue, I guess?).

I'll be offline the rest of this month so I'll see you guys in January!

[spiffxp]

/assign @dims
Seen as the "larger" umbrella issue that could maybe subsume #158 (which assumes we need GCR repos per project, maybe we find a way to promote images that doesn't require this)

[listx]

Happy New Year all!

The tool I've worked on was submitted for internal review yesterday (as part of Google's open sourcing process). After it gets approved, I will create a public demo of it in action and update this issue accordingly.

[dims]

very cool @listx thanks for the update and a very happy new year to you as well.

[listx]

Update: The project has been approved and the Container Image Promoter now lives in https://github.com/GoogleCloudPlatform/k8s-container-image-promoter. Work now begins in creating a public demo of it in action (I plan to devote cycles on this to get the demo working by the end of Q1 this year).

Once the demo is complete, I think it's just a matter of using it as a template for migrating some of the official images from gcr.io/google-containers to another (probably CNCF-owned) GCR. I just imagine a future where the K8s container image release process happens more transparently for the community. Hopefully the image promotion process is a solid step in that direction.

[listx]

The design doc for the demo around this can be found here: https://docs.google.com/document/d/1WGFt5ck_XGf71PO4c87UMPVU_4Q7AV-7tRV4Z6wmZL4/edit?usp=sharing