RFC: Detailed Quota Limits

[hexedpackets]

Problem

Quota limits are currently communicated through the .limits field in the MetricsResponse.

This only includes information about what kind of quota was violated, while a user would mostly be interested in what the effective limits violated are so that they can be worked around.

Suggestion

This suggestion is to change ResultLimit into an interface, which has different subtypes depending on the type of limit that was violated.

The .limits field would then change from:

{"limits": ["SERIES"]}

Into:

{
  "limits": [{
    "type": "series",
    "seriesLimit": 20000
  }]
}

This enhancement would allow the result set to communicate what the limit was, at the time of the query. This information can then be presented to the user, like:

Query required too many time series to be processed. The current limit is: 20000.

[hexedpackets]

PR proposing this: https://github.com/spotify/heroic/pull/196