Add bash completion for experimental CLI commands (manifest)

[albers]

This adds bash completion for docker manifest and its subcommands.

Completion for the manifest command is only activated if experimental CLI features are enabled (either by setting "experimental": "enabled" in .docker/config.json or the env var DOCKER_CLI_EXPERIMENTAL=enabled). This configuration setting is harvested from the output of docker version.

Before adding the third configuration setting that is extracted from docker version's output , I refactored the existing logic to a more consistent and clearer state. There is only one call to docker version. It is executed lazily and caches its result.

Note: The initial concept also included gathering the orchestrator in this step, but this piece of information went bananas in #1137.

In the context of docker version and its output, I changed the domain language to use server instead of daemon because this is the term used there (bounded context). daemon is better suited for local calls whereas server is more appropriate for (potentially) remote calls.

Edit: The list of valid os/arch values was taken from validOSArches in util.go. A comment was left as a reminder to keep both files in sync.

[codecov-io]

Codecov Report

Merging #1252 into master will not change coverage.
The diff coverage is n/a.

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[vdemeester]

SGTM 🎍

[albers]

@vdemeester It's still very basic with regard of the arguments. I don't know what are valid values for MANIFEST_LIST and MANIFEST:

Usage:  docker manifest create MANIFEST_LIST MANIFEST [MANIFEST...]

So I do not complete anything right now, allowing any string.

[albers]

@vdemeester Do you know who I might ask for help?

[vdemeester]

cc @clnperez @estesp @thaJeztah 👼

[clnperez]

@albers is there a check done for image names anywhere? the same rules apply (though I admit I don't know much about how the bash-completion verification works).

[albers]

@clnperez So I can use an image name as a MANIFEST?
I successfully tried docker manifest inspect alpine:3.6, but I got an error with

$ docker manifest create alpine-list alpine:3.6 alpine:3.7 alpine:3.8
docker.io/library/alpine:3.6 is a manifest list

Can you please give me a working example fo a manifest create command?

[clnperez]

There are some examples in the doc: https://docs.docker.com/engine/reference/commandline/manifest

Your issue is that alpine:3.6, alpine:3.7 and alpine:3.8 are all already manifest lists, and you can't make a recursive manifest list.

[albers]

@clnperez I found the examples not very helpful because they are not working code. There seem to be some prerequistes required for the commands to work apart from pulling down images and pushing them to a local registry.
I tried:

$ docker pull busybox:1.29.2-uclibc
$ docker tag busybox:1.29.2-uclibc localhost:5000/albers/busybox:1.29.2-uclibc
$ docker push localhost:5000/albers/busybox:1.29.2-uclibc
$ docker manifest create localhost:5000/albers/busybox:1.29.2 localhost:5000/albers/busybox:1.29.2-uclibc
no such manifest: localhost:5000/albers/busybox:1.29.2-uclibc

It's very hard to figure this out without understanding the relationship between images and manifests.
I assumed that each image has a manifest. Now it looks as some images are manifests. And it looks like manifests now can exist without images. What is a manifest list?

[clnperez]

three things:

• you shouldn't call a manifest list the same thing an your existing image. it will overwrite the name.
• can you try using the --insecure flag?
• a manifest list is explained in the extended description in the docs. or there's this blog i wrote a while back: https://developer.ibm.com/linuxonpower/2017/07/27/create-multi-architecture-docker-image/

[albers]

@clnperez Thanks very much for pointing me to your blog. This was exactly what I needed to understand the feature. I was able to create, annotate and push manifest lists.

[albers]

I added completion for manifest lists.
The completion is not perfect because there is no way to

• list unpushed manifest lists.
• get a list of all images with the manifest lists removed

As an approximation, I complete all images for both manifest lists and manifests.

[albers]

Added support for completion of --os and --arch (legal values), rebased and sqashed some commits.

This is now ready for review.
ping @clnperez @thaJeztah

[clnperez]

@albers This sounds reasonable to me. I might ask that we put a comment into the file you pulled those os & arch values from and in your PR that mentions that we should keep them in sync.

[albers]

... put a comment into the file you pulled those os & arch values from and in your PR that mentions that we should keep them in sync.

@clnperez Done.

[clnperez]

@vdemeester @thaJeztah Thoughts on this one?

[vdemeester]

Still LGTM

[silvin-lubecki]

Do we wait for #1355 to be merged ?

[albers]

@thaJeztah please review.

[thaJeztah]

LGTM

sorry, thought I already LGTM'd this one 😅