Question: Can DynamoDB trigger AWS Step Functions?

Answer

Yes. DynamoDB item changes can start a Step Functions workflow through EventBridge Pipes or a Lambda consumer of DynamoDB Streams. The table does not call Step Functions directly.

For a managed connection, enable a stream, create an EventBridge pipe with that stream as its source, and select the state machine as the target. Grant the pipe's role permission to read the stream and start the workflow. Use a filter and input transformation to send only the changes and fields the workflow needs.

Standard workflows are asynchronous targets. Express workflows support synchronous or asynchronous invocation, subject to the pipe source's ordering requirements. Choose an invocation mode supported by your particular source and workflow combination.

A Lambda consumer is useful when routing or validation requires custom code. It reads stream records and calls StartExecution with the workflow ARN and JSON input. The function needs both stream-read and state-machine permissions.

Plan for retries and repeated delivery. Use a stable business identifier and an idempotent workflow design; a single item change must not cause repeated charges or notifications. Also check payload size before forwarding complete old and new item images.

See DynamoDB Streams and Lambda triggers for source setup and failure handling.

Source: EventBridge Pipes targets.