What does this MR do?
This MR adds a Prometheus Service, with support for fetching metrics for an environment and displaying that on environments page.
We miss actual data fetching, but this is a placeholder that can be used to be worked on.
Are there points in the code the reviewer needs to double check?
Why was this MR needed?
Screenshots (if relevant)
Does this MR meet the acceptance criteria?
Changelog entry added
API support added
Added for this feature/bug
All builds are passing
Conform by the merge request performance guides
Conform by the style guides
Branch has no merge conflicts with
master(if it does - rebase it please)
Squashed related commits together
What are the relevant issue numbers?
Kamil: Please, edit queries and @jivanvl can add graphs to metrics action of environments_controller, as part of my MR: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/8935
Kamil: For development make sure to have sidekiq running as the data is fetched in the background, API can return the http status code 204 it means that the data is not yet ready, retry with some delay if that happens. In normal circumstances you will receive a 200 http status code with the JSON status: true
Josh: I spun up a prometheus server outside of the omnibus package, here: https://kubeprom.22.214.171.124.nip.io/graph. This one has the k8s metrics we want to use for this.