AWS Lambda Function Not Triggering on DynamoDB Stream with Batch Size Configuration
I'm migrating some code and I've been struggling with this for a few days now and could really use some help. I'm having trouble with my AWS Lambda function not being triggered by a DynamoDB stream as expected. The setup is relatively straightforward: I have a DynamoDB table that streams changes, and the stream is configured to trigger a Lambda function. However, even though the stream contains records, the Lambda function is not being invoked when I test it using specific batch sizes. I've tried adjusting the batch size in the event source mapping configuration, but I still encounter issues. For instance, when I set the batch size to 10, I see the following CloudWatch log messages, but no invocation occurs: ``` 2023-10-01T12:34:56.789Z - DynamoDB Stream Event Source: Batch size set to 10, but no records delivered. ``` My event source mapping looks like this: ```json { "BatchSize": 10, "EventSourceArn": "arn:aws:dynamodb:us-east-1:123456789012:table/MyTable/stream/2023-10-01T12:34:56.123", "FunctionArn": "arn:aws:lambda:us-east-1:123456789012:function:MyFunction", "StartingPosition": "LATEST" } ``` I have also checked the IAM roles and permissions, and they seem to be set up correctly. The Lambda function is configured to handle the incoming event with the following code: ```python import json def lambda_handler(event, context): for record in event['Records']: print(f"Record ID: {record['dynamodb']['Keys']}") return { 'statusCode': 200, 'body': json.dumps('Processed!') } ``` Still, no invocations happen when I manually insert items into the DynamoDB table. I've enabled the stream and confirmed that records are generated, so I'm at a loss here. I've even tried to change the `StartingPosition` to `TRIM_HORIZON`, but that didn't help either. Does anyone have insights on how to debug this situation or what might be causing the Lambda function not to trigger? Any help would be appreciated! This is part of a larger service I'm building. Has anyone else encountered this? Is there a better approach?