Proposal: Track rate limiting from GitHub API

[alexellis]

Context

When authenticated we have 50 requests to the API / hour. When we are authenticated we have 5k per hour +/-.

Idea: track rate-limiting

It's unlikely that we will burn up 5k in an hour on the OpenFaaS org, but larger projects may hit this and this should be observable.

What do we do?
How do we track this?

[rgee0]

A couple of initial notes while thinking.

GET /rate_limit exposes the values.

The limit appears to be distinct time-slices rather than a sliding window.

[alexellis]

Hmm is that a proposed API or a GH thing?

[alexellis]

Ok this.. https://developer.github.com/v3/rate_limit/

[alexellis]

We could definitely track it in alertmanager and send through to a webhook.

[alexellis]

Derek add label: priority/high

[alexellis]

I wonder if we should write a small function as a prometheus exporter which can produce this information for all the installations we have registered. It may involve us collecting the installation messages when the GitHub app is registered.

[Waterdrips]

https://developer.github.com/v3/#rate-limiting
The returned HTTP headers of any API request show your current rate limit status:

The remaining limit is in the X-RateLimit-Remaining header.

We could fire off some event when this gets low