Feature Request: Backfill data

[vikaslalwani]

I am not sure if this feature already exists. This may be another major iteration, or may need a different app altogether.

Metrics API recently saw a down time of few hours.
The idea here is to have something like a simple API call to back-fill those few hours of data with an overridable endpoint + metric format, ex. influx or Datadog, all while maintaining the same metric names as exposed by Prometheus in real-time.