Core NATS Subject specific metrics

[Nilesh Shinde]

Team,

I am looking for options on how to extract core NATS subjects details like -
1- Subject names
2 - In/Out bytes from specific subjects
3- dropped messages count
4 - application connection to subjects 
Want to push these metrics to Dynatrace. 
Any leads would be helpful.

Thanks in advance!

[derek]

For NATS core we do not hold additional state to track per subject statistics, this would need to be done externally. Also for #3 when we have a slow consumer, we do not actually know how many messages were dropped since at that point it is a queued opaque buffer.

For #4 you can list connections and filter them by subjects, so you can ask which connections are listening on `foo.*` for example.

[Nilesh Shinde]

Derek - Can we pull those core NATS subject statistics using bash scripts? or Any customized exporter? Our customer wanted more visibility on CORE NATS subjects.

[derek]

We do not track per subject statistics for messages in and out on NATS core, only via JetStream.