gitlab: authenticate through api_token specified in python-gitlab configuration files

[antimius]

Summary

We currently are using python-gitlab in several other python scripts and have set it up to use ~/.python-gitlab.cfg as the central source for our credentials (https://python-gitlab.readthedocs.io/en/stable/cli-usage.html#configuration-files). When using the community.general.gitlab_* modules however I have to specify the api_token explicitly. Would it be possible to try and fall back on default python-gitlab.cfg configuration when credentials are not specified?

Issue Type

Feature Idea

Component Name

gitlab_merge_request

Additional Information

- name: Create merge request
  community.general.gitlab_merge_request:
    api_url: "{{ gitlab_url }}"
    project: "{{ gitlab_repository }}"
    source_branch: feat/{{ jira_ticket }}
    target_branch: "{{ gitlab_target_branch }}"

Code of Conduct

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Files identified in the description:
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[ansibullbot]

Files identified in the description:

• plugins/modules/gitlab_merge_request.py

If these files are incorrect, please update the component name section of the description or use the !component bot command.

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cc @Lunik @Shaps @lgatellier @marwatk @metanovii @nejch @scodeman @sh0shin @suukit @waheedi @zanssa @zvaraondrej
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[felixfontein]

I'm not sure whether using that config file is a good idea, since python-gitlab can be seen as an implementation detail of the modules. (Though it doesn't look like we'll anytime soon change to another library...)

Something that migth simplyify using the modules is adding a module default group (similar to the community.general.consul and community.general.proxmox ones) that allows to set common parameters (like api_token) once in the playbook, and that will then be used by every gitlab_* module for which api_token isn't explicitly specified.

(Obviously also both supporting that config file and having a module defaults group could be implemented, if the module maintainers think that both are a good idea.)

[felixfontein]

(#8334 shows how to implement a module defaults group, also known as an action group.)