Feature request to add arguments --check and -q to docker pull command

[Alessar]

docker pull command allows download imagename:tagname from registry.
It will be good if there is argument (for example) --check that allows checking imagename:tagname in a registry (and checks that it can be downloaded if it is needed to provide authentication for example) but without downloading.
So, as a result, it is expected to see some info about imagename:tagname image if it can be downloaded or error in other cases.

It will be good if there is an argument -q (as in other commands) that allows printing only small info (for example) only tagname.

[thaJeztah]

Possibly docker could just do a HEAD request for the image / image-manifest, which should require the same authentication as performing a pull. However, performing a docker pull without having access to an image should already provide the same (as in: if you don't have access, the pull would fail and be terminated);

docker pull thajeztah/private-test-image
Using default tag: latest
Error response from daemon: pull access denied for thajeztah/private-test-image, repository does not exist or may require 'docker login': denied: requested access to the resource is denied

Could you perhaps describe your use-case a bit more?

[Alessar]

At first --check can divide authentication issue (when no permission on resource and we need run docker login command) and case when there is no specified tag on the image. In another case, we try to check the existing tag on the image and command docker pull downloads this image, but we need only check existence without downloading.

At second, we can run for example docker pull --all-tags alpine and we download all images from that repo. It is expected, that --check option can prevent downloading all tags and command only shows tags that can be downloaded from repo. For example it will show images, tags, digest, size (maybe some other info).

And of course -q options shows only minimal information from the table from --check option (for example only tag) like in commands docker ps -q or docker images -q.

[kbolino]

I've got a use case. Now that pull rate limits have been implemented, and they affect only and exactly GET of the manifest, having an option that does HEAD (which isn't rate limited) instead would be very useful, and this request seems pretty close to that.

[thaJeztah]

@kbolino docker 20.10 will cache manifests, and perform a HEAD request on pull to check if the image manifest is up to date before pulling (see #41607)

However, the HEAD requests are not yet part of the distribution specification (see opencontainers/distribution-spec#207 and opencontainers/distribution-spec#208), so currently can only be used as an optimisation for some registries