sam local does not support LocalStack S3 integration

warning

configurationUpdated May 25, 2024(via Exa)

Sources

Lambda Function Can't Access LocalStack S3 object When Invoked Locally · Issue #10897 · localstack/localstackgithub.com

Technologies:

LocalStacksubject

AWS LambdaAWS Lambda metrics correlate with this issue and help confirm diagnosis

How to detect:

sam local is a standalone AWS emulator that does not support S3 service integration. Lambda functions cannot access LocalStack S3 buckets when invoked via 'sam local' commands, as the emulator does not forward S3 API calls to LocalStack.

Recommended action:

Use 'samlocal' (LocalStack-maintained wrapper around SAM CLI) for local Lambda testing with S3 integration. Alternatively, use 'sam remote invoke' without the 'local' keyword, combined with a LocalStack profile configured with endpoint_url = http://localhost:4566 and s3.addressing_style = path.