EventBridge Pipes

Point-to-point integrations between a source and a target with optional content filtering and Lambda enrichment. Pipes runs as a separate AWS service (pipes) and uses RestJson1, not the EventBridge events bus.

Endpoint: http://localhost:4566Signing name: pipesProtocol: REST-JSON

Operations

Operation	Method / Path
CreatePipe	POST /v1/pipes/{Name}
DescribePipe	GET /v1/pipes/{Name}
ListPipes	GET /v1/pipes
UpdatePipe	PUT /v1/pipes/{Name}
DeletePipe	DELETE /v1/pipes/{Name}
StartPipe	POST /v1/pipes/{Name}/start
StopPipe	POST /v1/pipes/{Name}/stop
TagResource	POST /tags/{ResourceArn}
UntagResource	DELETE /tags/{ResourceArn}
ListTagsForResource	GET /tags/{ResourceArn}

ListPipes accepts the standard NamePrefix, SourcePrefix, TargetPrefix, CurrentState, and DesiredState query filters.

Runner behavior

A background runner spawned by the AWSim binary drives every pipe whose CurrentState is RUNNING:

1. Source poll. Reads up to SourceParameters.SqsQueueParameters.BatchSize messages from the source SQS queue (default 10).
2. Filter. Applies SourceParameters.FilterCriteria if present — same content-pattern syntax as Lambda event source mapping FilterCriteria (equality arrays, prefix, suffix, exists, anything-but, numeric). Records that fail the filter are deleted from the source queue.
3. Enrichment (optional). If Enrichment is a Lambda ARN, invokes it with the kept records as the payload and uses the response as the next-stage payload.
4. Target dispatch. Forwards the payload to the target. Source messages are deleted only after the target dispatch succeeds; failed dispatches leave them in the source queue for the next tick.

Supported sources

• SQS (arn:aws:sqs:...)

Supported targets

• Lambda function (arn:aws:lambda:...:function:NAME) — invoked with InvocationType=Event
• Step Functions state machine (arn:aws:states:...:stateMachine:NAME) — StartExecution
• SQS queue (arn:aws:sqs:...) — SendMessage
• SNS topic (arn:aws:sns:...) — Publish

Other source types (Kinesis, DynamoDB Streams, MSK) and target types (EventBridge bus, API destination, ECS task, etc.) accept the create call but the runner skips them — the pipe stays RUNNING but no records flow.

State machine

Create initializes CurrentState to RUNNING (or STOPPED if DesiredState=STOPPED was passed). StartPipe / StopPipe flip both CurrentState and DesiredState immediately — the emulator never lingers in transitional CREATING / STOPPING states the way real AWS does.

Persistence

When AWSim is started with --data-dir, pipes are snapshotted to disk and restored on the next startup. The runner picks up where it left off because pipe state lives in the snapshot.

Limitations

• Source-poll cadence is fixed at 2s. Real Pipes is event-driven.
• No CloudWatch Logs integration for LogConfiguration — the field round-trips on Describe but does not emit logs.
• MaximumBatchingWindowInSeconds and Concurrency parameters round-trip but are not honored by the runner.