*: add SupportedImageDestinationMIMEType to types.ImageDestination

[runcom]

This is an attempt to fix containers/skopeo#102 (comment) so we can move on with #23 w/o breaking skopeo copy when working with the Atomic Registry.

@mtrmac PTAL

Signed-off-by: Antonio Murdaca runcom@redhat.com

[runcom]

note to myself, should be plural

[mtrmac]

Actually isn’t this more requestedManifestMIMETypes? the Image has no concept of a destination, and the MIME types mostly affect what we read and serve.

[runcom]

it should be requestedManifestMIMETypes indeed

[runcom]

I'm sure design needs a better look - I integrated this code in containers/skopeo#102 in commit containers/skopeo@7624571 but I'm still unsure about the missing or nil arg in image.FromSource.

I'm wondering if the SupportedDestinationMIMETypes() should be static in the given package and not called from an instance of an ImageDestination because otherwise I can't use FromSource w/o first getting a given ImageDestination

[runcom]

EDIT: the above patch fixed the issue in skopeo :) - now, on design review here :)

[mtrmac]

• Destination is redundant, and so is Image (and are we talking about manifests only, or blobs as well?)
• Return a slice, so this should be plural.

{Supported,Accepted}{Manifest,}MIMETypes ?

[runcom]

Return a slice, so this should be plural.

#26 (comment)

SupportedMIMETypes() is ok for me

[runcom]

it's valid only for manifests also

[mtrmac]

I'm wondering if the SupportedDestinationMIMETypes() should be static in the given package and not called from an instance of an ImageDestination because otherwise I can't use FromSource w/o first getting a given ImageDestination.

It would be nice to have class methods instead of plain interfaces in Go.

… but in this case, actually it is desirable to have it as a method on ImageDestination. Just because a remote HTTP service speaks the docker/distribution protocol does not automatically mean that it accepts all future MIME types, getting the list of supported types may (or even should?) involve an API call to that service.

[runcom]

Updated PTAL @mtrmac

[mtrmac]

👍

[runcom]

lgtm

[runcom]

I'm going to rebase #23 and then go for the containers/skopeo#102 rebase as the final step