nats subject mapping does not work with jetstream

[tamalsaha]

Feature Request

I am trying to use NATS subject mapping where the dest subjects are used to create a jetstream. If I send request to the source subjects, I get nats: no responders available for request .

I would expect the jetstream to be able to ACK to the request even when subject mapping is used.

Use Case:

Proposed Change:

Who Benefits From The Change(s)?

Alternative Approaches

[ripienaar]

I use them with JS so best you show us some configs and code

[tamalsaha]

I followed the steps below using nats-server v2.9.14 .

nats-server -m 8222 -js

nats server mapping "ghactions.runs.*.*" "ghactions.machines.{{wildcard(1)}}.{{partition(3,2)}}"

> nats str create
? Stream Name ghactions
? Subjects ghactions.machines.*.*
? Storage file
? Replication 1
? Retention Policy Work Queue
? Discard Policy Old
? Stream Messages Limit -1
? Per Subject Messages Limit -1
? Total Stream Size -1
? Message TTL -1
? Max Message Size -1
? Duplicate tracking time window 2m0s
? Allow message Roll-ups No
? Allow message deletion Yes
? Allow purging subjects or the entire stream Yes
Stream ghactions was created

> nats request ghactions.runs.queued.1 "I need help!"

07:45:26 Sending request on "ghactions.runs.queued.1"
07:45:26 No responders are available

You can see the error No responders are available

> nats request ghactions.machines.queued.1 "I need help!"
08:00:02 Sending request on "ghactions.machines.queued.1"
08:00:02 Received with rtt 664.917µs
{"stream":"ghactions", "seq":1}

[tamalsaha]

Related issue: nats-io/natscli#703

[jnmoyne]

nats server mapping does not actually define and set a mapping on your existing running nats-serve(s), it's there only to test mappings.

With Core NATS you define the subject mappings either directly in the server configuration file, or (if you are using operator/JWT-based security) in the account JWT.

However it is most likely that the new/upcoming subject mapping transforms for streams is exactly what you are looking for. It has already been merged in the dev branch, and will be therefore included in the list of new features for NATS 2.10.
(see #3827) which allows you to define a subject mapping transform in the stream definition.

[tamalsaha]

In that case nats server mapping should be nats server test-mapping so it is clear that this is just client side testing.

[jhaynie]

i just ran into this as well ... lol, spent about 10m until i finally came here and found this thread.