Auto deletion of inactive durable consumers

[beatrausch]

Hi,

is there the possibility to configure nats to delete a durable consumer after a configurable amount of time of inactivity?

Regards

[bruth]

@beatrausch Can you define what you mean by "inactivity" and/or describe the use case in more detail? A consumer is a view of a stream and then one or more subscriptions are created (and bound) to that consumer to actually do the message handling.

[beatrausch]

@bruth Let’s say there is an app A for which a consumer A exists and this app is active over 3 months meaning there are from time-to-time subscriptions to its consumer A. After 3 months there are no more subscription to consumer A. The question is, if nats provide a mechanism to automatically remove this kind of “unused” consumer after a configurable amount of time of inactivity?

[bruth]

The short answer is no, there is no auto-deletion of consumers. However, consumer state is fairly minimal. Meaning even if consumers are around longer than they need to be, but are not active, there is only a small bit of state associated with them.

So then the question is how to detect and then clean up consumers. There is a Last (last active) field on SequenceInfo on ConsumerInfo.Delivered which would indicated the last time a message was delivered to any subscriber.

You could have a small program that loops through all consumers and checks that "last active" field to see if it passed the threshold of inactivity to be cleaned up.

[derekcollison]

Ephemeral consumers that are not active will be auto cleaned up.

For pull based (this is new so most clients not supporting it yet) this means no pull requests in the Inactivity time window (You can now set this as well).

For push it means the consumer is not bound for the same window.

[derekcollison]

https://github.com/nats-io/nats-server/blob/main/server/consumer.go#L78