Add docker_context_info module

[felixfontein]

SUMMARY

The goal is to have a module to query information on Docker contexts.

This also vendors the contexts part of the Docker SDK for Python (https://github.com/docker/docker-py/tree/main/docker/context).

ISSUE TYPE

• New Module Pull Request

COMPONENT NAME

docker_context_info

[github-actions]

Docs Build 📝

Thank you for contribution!✨

This PR has been merged and the docs are now incorporated into main:
https://ansible-collections.github.io/community.docker/branch/main

[felixfontein]

@ssbarnea this might be useful for you when trying to mix community.docker with Docker CLI tools (which consider Docker contexts). Something like

- name: Get current context
  community.docker.docker_context_info:
    only_current: true
  register: docker_current_context
- name: Run community.docker modules with current context
  module_defaults:
    group/community.docker.docker: "{{ docker_current_context.contexts[0].config }}"
  block:
    - name: Task using the current context
      community.docker.docker_container:
        image: ubuntu:latest
        name: ubuntu
        state: started

will allow you to run community.docker modules with Docker's current context.

[markuman]

Why is this copyright be docker? is it copied from some upstream sdk?

[felixfontein]

Yep, it's copied from https://github.com/docker/docker-py/

[markuman]

Suggested change

	host = parse_host(path, IS_WINDOWS_PLATFORM, tls)
	if host == DEFAULT_UNIX_SOCKET:
	# remove http+ from default docker socket url
	if host.startswith("http+"):
	host = host[5:]
	return host
	host = parse_host(path, IS_WINDOWS_PLATFORM, tls)
	# remove http+ from default docker socket url if exists
	return host.split("http+")[-1]

But I don't know how the host looks like when it's not a DEFAULT_UNIX_SOCKET.

[felixfontein]

I'd prefer not to change this, since it will be some divergence between the original Docker SDK for Python and this vendored version of the code that might break at some point in funny/unexpected ways.

Docker SDK for Python uses http+ or https+ before unix:// to indicate the exact protocol to use (with or without TLS), and at the same time tries to stay compatible with the Docker CLI programs that only use unix:// without http+ or https+ (and don't understand that). This check here is one of the places where it tries to return the same value that the CLI tools do, at least in one very specific case (namely the default Docker socket).

[felixfontein]

@markuman thanks a lot for reviewing this!