EventBridge Pipes — endpoint support

AWS docs: EventBridge Pipes API Reference

EventBridge Pipes uses REST-JSON under the /v1/pipes path prefix. Overcast supports full pipe CRUD, three source types, a Lambda enrichment step, and seven target types.

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Supported wiring

Leg	Supported	Refused at CreatePipe/UpdatePipe
Source	DynamoDB Streams, Kinesis streams, SQS queues	everything else, including Amazon MQ and Kafka
Enrichment	a Lambda function (optional)	API destinations, API Gateway, Step Functions
Target	Lambda, SQS, SNS, Step Functions, Kinesis, Firehose, EventBridge event bus	ECS tasks, Batch, CloudWatch Logs, Redshift Data, SageMaker, Timestream, API destinations

A combination Overcast cannot run is rejected with a ValidationException naming the offending field, so a pipe is never stored in a state where it would silently do nothing.

Notes

• Batches. A source produces a JSON array of records. A target with a batch API (SQS, SNS, Kinesis, Firehose, EventBridge bus) receives one entry per record; Lambda and Step Functions receive the whole array in a single request, as they do on AWS. BatchSize applies to the polled sources; a DynamoDB Streams source is driven one record at a time by the internal event bus, so it always runs a batch of one.
• Enrichment. The Lambda enrichment is invoked synchronously and its return value replaces the batch. An empty response ("", {}, [], null) drops the batch without invoking the target; [{}] invokes the target with an empty payload.
• Input transformation. EnrichmentParameters.InputTemplate and TargetParameters.InputTemplate are applied to each record individually, over the JSON-path subset AWS accepts plus the aws.pipes.* reserved variables.
• Polling. Kinesis and SQS sources are polled once per second on the emulator’s clock. An SQS source retries by leaving failed messages to become visible again — AWS dead-letters an SQS-sourced pipe through the queue’s own RedrivePolicy, not DeadLetterConfig, so Overcast does nothing further there.
• Stream retries and dead-lettering (Kinesis and DynamoDB Streams). Both stream sources share AWS’s MaximumRetryAttempts/DeadLetterConfig shape and the same retry-then-dead-letter contract, capped at 5 retries (unset means AWS’s “retry until the record expires”, which the cap stands in for; an explicit 0 means one attempt). A Kinesis batch is retried by leaving the shard cursor alone for one poll tick per attempt; a DynamoDB Streams batch has no cursor to leave alone — it arrives over the internal event bus and is gone once the subscriber returns — so it is retried in place instead. Once the retries are exhausted the batch is sent to the source’s DeadLetterConfig SQS queue or SNS topic if one is configured (reported as dlq on the delivery feed), and otherwise reported as failed with a logged warning, and the cursor/subscription moves on rather than blocking on the batch forever. Overcast dead-letters the source records themselves rather than AWS’s shard/sequence-range failure envelope — Lambda’s own on-failure destination for a Kinesis event source mapping sends only that metadata (KinesisBatchInfo: shardId, startSequenceNumber, endSequenceNumber, streamArn), not the records, so a consumer re-reads them from the stream before they expire. Overcast keeps no shard/sequence bookkeeping to build that envelope from — for the DynamoDB source because delivery is bus-driven, and for Kinesis for consistency with it — so the records are sent instead, which is what makes the batch replayable without a second read. A DeadLetterConfig naming a destination that is not an SQS queue or an SNS topic is refused at CreatePipe/UpdatePipe time rather than stored.
• Filtering is not emulated. SourceParameters.FilterCriteria is rejected rather than stored and ignored — filter inside a Lambda enrichment instead.
• UpdatePipe is PUT /v1/pipes/{name}, as AWS routes it, and requires RoleArn.
• Async state machine. Pipe state transitions (CREATING→RUNNING, UPDATING→RUNNING, STOPPING→STOPPED, …) happen asynchronously with a short delay.
• Start/stop. Setting DesiredState to STOPPED or RUNNING on update triggers the appropriate state transition.
• Partial batch responses. A Lambda target’s response is read for a batchItemFailures report, and the records it names are the only ones redelivered: an SQS source deletes the rest and leaves the reported messages to become visible again, a Kinesis source moves its shard cursor to just before the earliest reported record, and a DynamoDB Streams source retries from that record onwards. A report Overcast cannot honour — invalid JSON, an empty or missing itemIdentifier, an identifier naming a record that was not in the batch — retries the whole batch and is logged with the reason. A pipe has no FunctionResponseTypes to opt in with, so a response that never mentions batchItemFailures is left alone rather than second-guessed; that is what keeps a target returning a non-JSON payload succeeding as it always did. Two places still do not report: a Step Functions target, whose asynchronous StartExecution has no response to read, and a Lambda enrichment, whose return value AWS defines as replacing the batch rather than reporting on it. AWS offers no partial-batch reporting for any other target type.
• Stored but not acted on. LogConfiguration, KmsKeyIdentifier and ParallelizationFactor have no effect. RoleArn is required, as AWS requires it, but is not evaluated — Overcast is not a security boundary.

Summary

Category	✅ Supported
Pipes	5
Tags	3

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Endpoints

Pipes

Operation	Status	Notes	AWS Docs
CreatePipe	✅ Supported	Validates source/enrichment/target wiring up front, including a stream source’s DeadLetterConfig destination; async state machine (CREATING→RUNNING)	docs
DescribePipe	✅ Supported	Returns the full pipe configuration and current state	docs
UpdatePipe	✅ Supported	Updates DesiredState, description, role and parameter blocks, re-validating wiring and DeadLetterConfig on a reconfiguring change (UPDATING→previous state)	docs
DeletePipe	✅ Supported	Async deletion (DELETING→removed)	docs
ListPipes	✅ Supported	Lists all pipes as PipeSummary	docs

Tags

Operation	Status	Notes	AWS Docs
TagResource	✅ Supported	Adds/merges tags by pipe ARN	docs
UntagResource	✅ Supported	Removes tags by key from a pipe ARN	docs
ListTagsForResource	✅ Supported	Returns tags for a pipe ARN	docs