User-friendly way to move projects between repository storages

Problem to solve

Currently, the best documented method of moving a Git repositories backing storage (Gitaly node) is done via a cURL request, per our production team's Runbooks.

This is a fully functional EE API call (added in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/533), so there should not be an excessive amount of work to expose this to an admin via the UI, when looking at an individual project's settings. The API doesn't offer a user-friendly interface to perform the moves. This is OK for GitLab infrastructure or occasional bulk moves, but it's not the best experience for our customers, e.g.: https://gitlab.zendesk.com/agent/tickets/48746

Intended users

Admins

Further details

An instance admin is required to:

1. Create a personal access token, with high levels of access
2. Look up a project's project ID
3. Look up the names of Gitaly nodes' storage paths
4. Hand craft a HTTP PUT request with cURL command line
5. Verify success or failure by checking the underlying Gitaly servers
6. Manually remove old repo folder

Proposal

• Expose this functionality to change repository store through an Admin only accessible section of the project settings UI. If you run API today you need to run gitlab:cleanup:moved to cleanup but we should do the move more cleanly via UI.

Even better:

• Enhance the bulk project update worker so admins can move multiple projects at a time

Permissions and Security

Documentation

Document it, the cleanup rake task, and the API fallback too, here: http://docs.gitlab.com/ce/administration/repository_storages.html

Testing

What does success look like, and how can we measure that?

A GitLab instance administrator can relocate a project's repositories through the UI, in a fashion that is intuitive and concise. At the moment, there is no functionality for this.

Links / references

Production's Runbook for howoto/sharding

Existing documentation about moving repositories