Struct Config 

pub struct Config<C> {
    pub stream: Config,
    pub consumer: C,
    pub heartbeat: Duration,
}

Fields

stream: Config

consumer: C

heartbeat: Duration

Implementations

impl Config<()>

pub fn new(namespace: &str) -> Self

Create a new JetStream configuration scoped to a namespace.

This initializes the underlying stream with the given namespace as its name. No consumer type is selected at this stage — you must choose one of Config::with_pull_consumer, Config::with_push_consumer.

Arguments

• namespace: Logical name used for the stream.

pub fn with_pull_consumer(self) -> Config<Config>

Configure a pull-based consumer.

In this mode, the client explicitly requests messages using APIs like fetch or next. This provides strong control over throughput and natural backpressure.

Characteristics

• Client-driven (you decide when/how many messages to receive)
• Supports acknowledgements and redelivery
• Durable and fault-tolerant

Use cases

• Job queues
• Worker systems
• Batch processing

Notes

• Does not support features like idle_heartbeat
• Recommended default for most backend processing systems

pub fn with_ordered_pull_consumer(self) -> Config<OrderedConfig>

Configure an ordered pull-based consumer.

This is a simplified pull consumer that guarantees strict message ordering, but disables reliability features such as acknowledgements and redelivery.

Characteristics

• Strict ordering guaranteed
• No acknowledgements
• No redelivery on failure
• Ephemeral (non-durable)

Behavior

If a message is missed or a sequence gap is detected, the consumer is transparently reset to a new position.

Use cases

• Stream inspection
• Debugging
• Replay / analytics pipelines where occasional loss is acceptable

⚠️ Warning

Do not use for job processing or systems requiring reliability.

pub fn with_push_consumer(self) -> Config<Config>

Configure a push-based consumer.

In this mode, JetStream delivers messages to a subject (deliver_subject) and the client subscribes to that subject.

Characteristics

• Server-driven (messages are pushed to the client)
• Supports acknowledgements and redelivery
• Can be combined with queue groups for load balancing

Use cases

• Event-driven systems
• Real-time pipelines
• Reactive services

Notes

• Supports features like idle_heartbeat and flow control
• Requires configuring a deliver_subject defaults to apalis-worker-group

pub fn with_ordered_push_consumer(self) -> Config<OrderedConfig>

Configure an ordered push-based consumer.

This is a push consumer that guarantees strict ordering, but removes reliability guarantees such as acknowledgements and redelivery.

Characteristics

• Strict ordering guaranteed
• No acknowledgements
• No redelivery
• Ephemeral (non-durable)

Behavior

If message delivery order is disrupted, the consumer is automatically recreated and resumes from a new position.

Use cases

• Observability pipelines
• Real-time stream inspection
• Monitoring and debugging

⚠️ Warning

Not suitable for production job processing or any system that requires guaranteed delivery.

impl Config<Config>

pub fn durable(self) -> Self

pub fn with_description(self, desc: impl Into<String>) -> Self

pub fn with_ack_policy(self, policy: AckPolicy) -> Self

pub fn with_ack_wait(self, wait: Duration) -> Self

pub fn with_max_deliver(self, max: i64) -> Self

pub fn with_filter_subject(self, subject: impl Into<String>) -> Self

pub fn with_replay_policy(self, policy: ReplayPolicy) -> Self

pub fn with_rate_limit(self, rate: u64) -> Self

pub fn with_max_ack_pending(self, max: i64) -> Self

pub fn with_backoff(self, backoff: Vec<Duration>) -> Self

pub fn with_inactive_threshold(self, threshold: Duration) -> Self

impl Config<Config>

pub fn durable(self) -> Self

pub fn with_description(self, desc: impl Into<String>) -> Self

pub fn with_deliver_group(self, group: impl Into<String>) -> Self

pub fn with_ack_policy(self, policy: AckPolicy) -> Self

pub fn with_ack_wait(self, wait: Duration) -> Self

pub fn with_max_deliver(self, max: i64) -> Self

pub fn with_filter_subject(self, subject: impl Into<String>) -> Self

pub fn with_replay_policy(self, policy: ReplayPolicy) -> Self

pub fn with_rate_limit(self, rate: u64) -> Self

pub fn with_max_ack_pending(self, max: i64) -> Self

pub fn with_flow_control(self, enabled: bool) -> Self

pub fn with_idle_heartbeat(self, hb: Duration) -> Self

pub fn with_backoff(self, backoff: Vec<Duration>) -> Self

pub fn with_inactive_threshold(self, threshold: Duration) -> Self

Trait Implementations

impl<C: Clone> Clone for Config<C>

fn clone(&self) -> Config<C>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<C: Debug> Debug for Config<C>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.