Does prometheus golang (echo-contrib) exporter saves metrics in memory?

Question

I have a GoLang middleware for exporting metrics for prometheus, which are then served from /metrics endpoint

My question is where does the data received from /metrics endpoint come from? Does it come from the memory?

Exporter link:https://github.com/labstack/echo-contrib/tree/master/prometheus

Answer 1

Yes, the last state of the metrics are stored in memory of the scraped target. Most of the implementation of prometheus metrics are built with this library in go programs: https://github.com/prometheus/client_golang

Your scraped target won't hold the whole time serie, it's prometheus role to store these values across time.