I need to add gauges from a scheduler to MeterRegistry. I register new gauges and they appear in Prometheus output, but the value functions aren’t being called. It leads to NaN values on the added metrics in prometheus.

I tried to add those gauges with MeterBinder and it works fine, but I need to do it at runtime due to the nature of these metrics.

In brief, my flow looks like following:

1. Each N minutes retrieve all existing entities from the db
2. Remove metrics for removed entities
3. Add gauges for new entities
4. In the value function of the gauge go to redis, fetch the state and return the value

Thus, I can’t just add them at startup.