How to set up and experiment with Prometheus remote-write

Prometheus is an open source monitoring software. It stores time series for metrics, where each metric is defined by a name and a unique set of arbitrary key-value pairs called labels. The only thing that changes for a given time series throughout the course of time is its value—a numeric value of a given type.

Prometheus is collecting those metrics by pulling on HTTP endpoints that expose a plaintext page containing a list of metrics (each with name and labels) together with their current value.