Default Configs

The transport ships with production-ready defaults for every stream and consumer type. This page lists the exact values from the source code. All defaults can be overridden via module configuration.

Stream Defaults

All streams share a common base configuration:

Property	Value
retention	Workqueue (overridden per type below)
storage	File
num_replicas	1
discard	Old
allow_direct	true
compression	S2

S2 Compression

All streams default to Snappy S2 compression. This reduces disk I/O and storage with negligible CPU overhead (~1-3%). Requires NATS Server >= 2.10 (see runtime requirements). Override per stream kind:

import { StoreCompression } from '@nats-io/jetstream';

events: {
  stream: { compression: StoreCompression.None }, // disable for event streams
}

Event Stream

Workqueue retention — each message is removed after being acknowledged by a consumer.

Property	Value	Notes
retention	Workqueue
storage	File
num_replicas	1
allow_rollup_hdrs	true
max_consumers	100
max_msg_size	10 MB	10,485,760 bytes
max_msgs_per_subject	5,000,000
max_msgs	50,000,000
max_bytes	5 GB	5,368,709,120 bytes
max_age	7 days	toNanos(7, 'days')
duplicate_window	2 minutes	toNanos(2, 'minutes')

Scheduling

To enable message scheduling, add allow_msg_schedules: true to the event stream config. This requires NATS Server >= 2.12.

Command Stream

Short-lived RPC commands (JetStream RPC mode only).

Property	Value	Notes
retention	Workqueue
storage	File
num_replicas	1
allow_rollup_hdrs	false
max_consumers	50
max_msg_size	5 MB	5,242,880 bytes
max_msgs_per_subject	100,000
max_msgs	1,000,000
max_bytes	100 MB	104,857,600 bytes
max_age	3 minutes	toNanos(3, 'minutes')
duplicate_window	30 seconds	toNanos(30, 'seconds')

Broadcast Stream

Limits retention — messages persist until the configured limits are reached. Shared across all services.

Property	Value	Notes
retention	Limits
storage	File
num_replicas	1
allow_rollup_hdrs	true
max_consumers	200
max_msg_size	10 MB	10,485,760 bytes
max_msgs_per_subject	1,000,000
max_msgs	10,000,000
max_bytes	2 GB	2,147,483,648 bytes
max_age	1 day	toNanos(1, 'days')
duplicate_window	2 minutes	toNanos(2, 'minutes')

Ordered Stream

Limits retention for strict sequential delivery. Ordered consumers are ephemeral.

Property	Value	Notes
retention	Limits
storage	File
num_replicas	1
allow_rollup_hdrs	false
max_consumers	100
max_msg_size	10 MB	10,485,760 bytes
max_msgs_per_subject	5,000,000
max_msgs	50,000,000
max_bytes	5 GB	5,368,709,120 bytes
max_age	1 day	toNanos(1, 'days')
duplicate_window	2 minutes	toNanos(2, 'minutes')

Consumer Defaults

Event Consumer

Property	Value	Notes
ack_wait	10 seconds	toNanos(10, 'seconds')
max_deliver	3	Message moves to dead-letter after 3 failed attempts
max_ack_pending	100
ack_policy	Explicit
deliver_policy	All
replay_policy	Instant

Command Consumer

Property	Value	Notes
ack_wait	5 minutes	toNanos(5, 'minutes')
max_deliver	1	No retries — RPC failures propagate immediately
max_ack_pending	100
ack_policy	Explicit
deliver_policy	All
replay_policy	Instant

Broadcast Consumer

Property	Value	Notes
ack_wait	10 seconds	toNanos(10, 'seconds')
max_deliver	3
max_ack_pending	100
ack_policy	Explicit
deliver_policy	All
replay_policy	Instant

note

Ordered consumers do not have a durable consumer configuration. They are ephemeral and managed entirely by the @nats-io/jetstream client library.

Connection Defaults

The transport applies the following connection defaults for production resilience:

Property	Value	Notes
maxReconnectAttempts	-1	Unlimited reconnection attempts
reconnectTimeWait	1000	1 second between reconnection attempts

These defaults ensure the transport automatically recovers from transient network failures without manual intervention. Override them via connectionOptions in forRoot():

JetstreamModule.forRoot({
  name: 'orders',
  servers: ['nats://localhost:4222'],
  connectionOptions: {
    maxReconnectAttempts: 10,   // limit to 10 attempts
    reconnectTimeWait: 2_000,  // 2 seconds between attempts
  },
})

RPC Timeouts

Mode	Default Timeout	Constant
Core (standard NATS request-reply)	30 seconds	DEFAULT_RPC_TIMEOUT
JetStream (persistent RPC)	3 minutes	DEFAULT_JETSTREAM_RPC_TIMEOUT

The JetStream RPC timeout is intentionally longer because messages are persisted to a stream and the consumer may take time to process them.

Graceful Shutdown Timeout

Property	Value
Shutdown timeout	10 seconds

The transport waits up to 10 seconds for in-flight messages to be processed before forcing shutdown via drain().

Overriding Defaults

All stream and consumer defaults can be overridden in forRoot() options. User-provided values are merged on top of the defaults — you only need to specify the properties you want to change.

import { RetentionPolicy, StorageType } from '@nats-io/jetstream';
import { JetstreamModule, toNanos } from '@horizon-republic/nestjs-jetstream';

JetstreamModule.forRoot({
  name: 'orders',
  servers: ['nats://localhost:4222'],
  events: {
    stream: {
      storage: StorageType.Memory,   // override just storage type
      max_age: toNanos(3, 'days'), // 3 days instead of 7
    },
    consumer: {
      max_deliver: 5, // 5 retries instead of 3
    },
  },
  rpc: {
    mode: 'jetstream',
    timeout: 60_000, // 1 minute instead of 3
    stream: {
      max_msg_size: 1024 * 1024, // 1 MB limit for RPC payloads
    },
  },
});

See Module Configuration for the full options reference.