Implementation of charts inside gitlab-ui

Let's use this issue to capture initial discussion about possibilities of implementation of charts within gitlab-ui.

Thoughts on possible implementation details are welcome in this issue

Following an enquire to the Product team, we've compiled this google doc, which lead to this set of requirements:

Requirements/concerns:

1. FAST development cycles
2. Easily reusable charts (see 1)
3. Dynamic data: able to fetch new data from server and re-render chart on demand.
4. Good customisation options as we need several types of charts (lines, bars, stacked, etc.).
   1. Interaction usually based around revealing popovers with more info/html.
   2. Needs ability to specify behaviours when certain parts of chart are clicked.
5. Compatibility: in the past SVG compatibility in Firefox has caused problems/broken charts.
6. Testable including visual diffing.

Related

• UX team is capturing feedback/wishlists in this issue: gitlab-design#203 (closed)