Java, including SpringBoot, performs very well, but has a slow start. If you're doing ETL/data processing then you don't really care about the slow start (versus serving real time requests to end users). You will need to use larger RAM/CPU but it works fine. Quarkus, Micronaut, and Spring via Graal are all good options as well. More on reddit.com

Very often the best language for a team/org is not the "best" language for particular component. If it's a Java based team it often doesn't make sense to dump all that investment just for Lambda if Java performance there is acceptable. Personally I won't use Node for anything if I can possibly avoid it. If Python isn't fast enough and in particular if threading will help I'll use Go. But even as anti-Node as I admit I am, I absolutely respect that in shops with a lot of Javascript talent due to frontend work it often makes the most sense to go with Node for backend work despite its many hair pulling issues. It's much better to be pragmatic than "right". Lambda supports a ton of languages (effectively all of them if we count custom runtimes) because it's pragmatic. More on reddit.com

The lambda API (and thus the Java SDK) has a CreateFunction action. You can provide the raw bytes of the zipped lambda package or specify a location in S3. Conversely there is a GetFunction action that will provide the existing config for a function (including a pre-signed url to download the code) for an already uploaded lambda package. So you could replicate your functions and/or create in multiple regions using these APIs. As a general rule, anything you can do in the console you can do via the SDK. edit: I'd also recommend looking into using an IaC solution for creating your functions in multiple regions. Something like Cloudformation, CDK, or Terraform can make deploying identical resources across multiple accounts/regions a lot smoother. More on reddit.com

You can get close to mimicing execution locally. Since Lambda calls a specific function (lambdaHandler), is there a way in java to code in a test to see if you are calling from the CLI (locally)? I do this in Python by doing a check: if __name__ == "__main__": # This section is used for testing code outside of Lambda # To mimic role permissions, ensure AWS_DEFAULT_PROFILE # or AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY and AWS_DEFAULT_REGION # environment variables are set. # Change the dict below to mimic submission of a JSON formatted event # This function doesn't use event or context variables event = {'key1': 'value', 'key2': 'value'} lambda_handler(event, '') In this case if I call locally, the final section of code (if __name__...) is seen, it's because I call locally. Then I craft (per function) a JSON object for the event and pass it along to the actual function Lambda will call (lambda_handler() in my case). You could craft the context object also. Then locally I use an AWS_PROFILE that has the same policy that will be applied to the function, so that any AWS resources called will have the same permissions for the role/principal. More on reddit.com