I am writing an exporter and am having trouble with metrics for my collector. From what I can tell, metrics in Prometheus need to be defined beforehand. Is there any way to define them dynamically at runtime instead? I won't know how many metrics I'll have or what metrics I'll need until the code is running. (For example, if k8s finds all volumes connected to the cluster, and I need EACH volume to get its own total_capacity/available_capacity metric).
2 Answers
You would handle this by using dynamic label values rather than dynamic metric names. That said, you can call prometheus.Register() at runtime just fine, client_golang won't know the difference.
I have only used Python and Java Prometheus clients so far, but isn't it just a recommendation to define metrics beforehand? In Java I can create the metrics at run-time inside methods or wherever I want. I just have to make sure that the same metric is not created again or an exception will be thrown by the library.
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