REST API Endpoint for groups that a group was invited to

Release notes

Add REST API endpoint for groups that a group was invited to.

Problem to solve

As a DevOps Engineer, I want access to the groups that a group has access to via the API (and GUI) so that I can "link" groups together.

This functionality already exists at the project level, and groups can already be shared with other groups. However, this functionality does not have great accessibility to users at the moment.

Intended users

• Priyanka (Platform Engineer) - For creating CI/CD that needs to traverse the group structure
• Sasha (Software Developer) - Transparency into what groups are accessible and/or relevant to their group

User experience goal

The user should be able to query the API and find in the UI groups that their group has access to (similar to projects).

Further details

Use cases

• Traversing a group tree structure, similar to a "link" in a filesystem.
  • This is helpful in cases where we want a subgroup to be accessible to multiple other groups, especially when the subgroup is independent of the other subgroups.

Permissions and Security

This should reflect the existing Groups API endpoint and GUI permissions. Not sure what those are, exactly.

Documentation

• Groups API Documentation
• Groups Documentation

Available Tier

• Free (with the rest of these features)

Proposal

• Create a REST API endpoint to List a group's shared groups, similar to this one, so that GET /groups/:id/groups/shared is available.
  • Ensure the returned results are only accessible to group Owners and admins
• Ensure the new endpoint is rate limited
• Update docs: https://docs.gitlab.com/ee/api/groups.html