MediaType validation too aggressive

[stevvooe]

The mediaType validation for the manifest getter is too aggressive: https://github.com/docker/distribution/blob/master/registry/storage/manifeststore.go#L98.

This prevents the fetching of content by digest which would fail validation on the client. This validation will make it hard to upgrade in the future.

cc @caervs

[jonjohnsonjr]

Could you expand on this a little bit? Is this related to #2076?

[stevvooe]

@jonjohnsonjr The registry should be fairly agnostic about the format it is returning. Also, the current code relies on the existence of an embedded mediaType field, which is problematic, as the types are supposed to be external.

In general, the current approach will make #2076 harder.

[davidspek]

@milosgajdos Is this still relevant since #2076 has since been merged? Also, should the v3 release be blocked on this?

[milosgajdos]

@stevvooe do you wanna close this issue?

[davidspek]

@milosgajdos Can this be closed given that #2076 was merged?

[milosgajdos]

This issue seems outdated and I'm not sure it's addressed by #2076. Equally, it's 6 years old and may already be forgotten. Not quite sure what the step forward here should be without clarification from the reporter.

[davidspek]

Lets close it. If the issue is still relevant it can be re-opened or a new issue can be created.