Add completion for docker-compose plugin

[ulyssessouza]

WIP: Note that this PR depends on the implementation of completions PR in docker/compose-cli to work.

[codecov-commenter]

Codecov Report

Merging #3158 (efba76c) into master (5f07d7d) will increase coverage by 1.50%.
The diff coverage is n/a.

❗ Current head efba76c differs from pull request most recent head 5a8d7d5. Consider uploading reports for the commit 5a8d7d5 to get more accurate results

@@            Coverage Diff             @@
##           master    #3158      +/-   ##
==========================================
+ Coverage   57.08%   58.58%   +1.50%     
==========================================
  Files         299      299              
  Lines       18756    21476    +2720     
==========================================
+ Hits        10707    12582    +1875     
- Misses       7178     7972     +794     
- Partials      871      922      +51     

[albers]

I think this PR is a very good starting point to gain some experience with generated completions.
We could start with a hardcoded option to include completion for the compose plugin, as suggested in this PR.

The completion script could check the well-known install locations (/usr/libexec/docker/cli-plugins/ and ~/.docker/cli-plugins/ for the presence of the docker-compose plugin file. In case of a match, it should activate completion for the plugin.

In subsequent PRs, the completion script should be extended to provide a generic solution for client plugins.

The generated completion as implemented in this PR works quite well, but should also be improved in subsequent PRs. For example, I miss support for completion of local files (docker compose -f), and completion of service names (docker compose logs)

[thaJeztah]

for #3158 (comment)

I should not that if we do want to use the above docker info to get that information, and we must do that on every request, we should have a look if we can somehow get the info without the CLI also making an API call (to the /info endpoint) 😬

I opened #3179, which should be able to detect if we're only using local information (in which case it will skip making an API connection to the /info endpoint.

[albers]

For consistency, please avoid unneccessary braces in variables, e.g. "${value}" should be just "$value". For the same reason please pull up the do.

[albers]

Very well.
One last nit and a question.

[albers]

LGTM, thanks!
ping @thaJeztah

[thaJeztah]

LGTM

tried it inside a container, and looks to work ok 👍

I also see spf13/cobra#1146 was merged, which looks to be improving cobra's completion scripts as well (instead of generating massive scripts)

[ulyssessouza]

Thanks a lot @albers & @thaJeztah !

[albers]

@ulyssessouza Please keep me up to date with your further work on generated completions.