How to define channel specific configuration in nats-jetstream

[anil1996]

Hello,

We are planning to move to nats-jetstream from nats-streaming.
Is there any option available to define channel specific configuration in jetstream, like how it is available in nats-streaming?
For example:
stan.conf content

Maximum Payload allowed

max_payload: 4MB

stan message bus configuration file

store_limits: {
# Override some global limits
max_msgs: 200
# Global limit for all topics
max_bytes: 128MB
max_age: "5m"

# Per channel configuration.
# Can be channels, channels_limits, per_channel, per_channel_limits or ChannelsLimits
channels: {
    "test1": {
        # Possible options are the same than in the store_limits section, except
        # for max_channels. Not all limits need to be specified.
        max_msgs: 0
    }
}

}

how can I achieve same configuration in jetstream???

[ripienaar]

No unfortunately not, you have to use the API, CLI, Terraform or GitHub Actions

[anil1996]

Hi @ripienaar Thanks for your response.

As per my understanding it's possible to configure max_msgs, max_bytes, and max_age. It also seems possible to set max-msgs-per-subject, but this configuration max-msgs-per-subject sets it uniformly for all subjects in a stream. Can I have customized values for different subjects ?
for eg: stream A contains test1 and test2 subjects.
is it possible to set max-msgs-per-subject 2 for test1 and 3 for test2??

[ripienaar]

No, as you say its per stream

[anil1996]

Ok Thank you.
So I have to create different different streams.
One more clarification needed.
I have chosen storage to be memory , I have 100 streams 1 replica and I am restricting each stream with max bytes as 128MB. When I start server with jetstream enabled I can see max memory as 8.77GB but my configuration file looks like this

jetstream {
max_file: 0
}

since max memory is 8.77GB and I have 100 streams with max bytes as 128MB, so combined memory is ~12GB.
While creating streams using go clients I am getting insufficient resource error.

So does nats pre allocates memory for all these streams or its just a check to ensure that I have enough memory combined to create all these streams???
I checked RAM usage for nats-server and its around ~34.4 MiB.