Provide a way to access Lambda Context in Python

[unexge]

lambda_http crate provides RequestExt trait to allow accessing some additional information. Currently we convert Lambda request to Hyper request in: https://github.com/awslabs/smithy-rs/blob/main/rust-runtime/aws-smithy-http-server/src/routing/lambda_handler.rs#L49-L89 and we lose the information that specific to Lambda. Ideally we should provide a way to access that information.

I'm not sure what is the best way to do that, maybe we can discuss about adding Lambda specific traits to Smithy IDL, or maybe we can provide that information via Request::extensions in Rust and with a app.lambda_context decorator in Python.

[david-perez]

Most of that information is stored in request extensions already by the Lambda runtime (e.g. RequestContext), which we preserve in that convert_event function since we reconstruct the request with the converted body type using http::Request::from_parts(parts, body).

So to access it as of now, the user just has to model it in their State and AddExtensionLayer will take care of extracting it.

However, I do think that the general problem of threading request-specific state to service handlers (as opposed to global application state), which includes things like Lambda context, peer IP address, request ID, etc. needs to be solved more ergonomically.

[unexge]

@david-perez ohh I missed that. I'll convert this issue to be Python specific. Do we have a tracking ticket for the last part or do you want me to create a ticket for that?