This is a small proxy to be used as Grafana datasource to dynamically modify queries to a Prometheus API.

It currently supports modifying the following URL-encoded parameters which are encoded in the URL:

• start
• end
• time

For more information about the parameters have a look at the Prometheus docs.

I was building a Grafana Dashboard having day-specific values. The sum of a day was always shown with the timestamp of the next day which may be a bit confusing for end-users. By adjusting the start, end or time parameters by defining different datasources I was able to shift the queries to:

• Show not too much values in my table.
• Shift the timestamp by 1 second to show the last second of the day (23:59:59) instead of the next day.

I was not able to achieve the same by Grafana configuration and that's why I have written this small proxy.

To adjust the parameters configure PromShift Proxy as normal Prometheus datasource and configure your datasource at Custom Query Parameters.

The following configuration would:

• add 23h to the timestamp start (if the parameter exists in the request)
• subtract 1h from the timestamp end (if the parameter exists in the request)
• subtract 1h from the timestamp time (if the parameter exists in the request)

start=23h&end=-1h&time=-1h