Sidekiq infra for pull mirrors
RE: https://gitlab.com/gitlab-org/gitlab-ee/issues/3021#note_36460602
@pcarranza Can I please get Sidekiq infra for pull mirrors? :)
For this first iteration, ideally we'd get concurrency of 20: 20 mirrors being updated at the same time.
You likely have a better idea of the number of hosts, and CPU/RAM required.