Add support for streaming responses in api gateway

[andidev]

This adds support for "Amazon API Gateway Streaming REST apis"
Feature was released in AWS around Nov 19, 2025 and is helpful when developing serverless lambda AI APIs and apis that take longer than the API Gateway timeout limit of 29 seconds.

see https://aws.amazon.com/about-aws/whats-new/2025/11/api-gateway-response-streaming-rest-apis/

[andidev]

I have already added support for serverless-offline project. I still need to fine tune the implementation and agree with the repo owners of the serverless-offline project to add support for it.
Not sure how they handle/want to handle the serverless v3 fork situation.

PR is created at least, see dherault/serverless-offline#1871

[jernaumorat]

Keen to know what is blocking this being merged; we have a few places where this is now needed and have very janky workarounds in place

[Arit143]

bumping it +1

[mnapoli]

Hey everyone, the status is red

[andidev]

It is fixed now, was a small eslit rule causing it.
@mnapoli can you approve so checks run again?

I see though that there is some usage of ?. in code that fails in main branch since the min allowed node version is set to 12.
Think we should change to enforce at least node 14 to allow optional chaining in projects or actually change code to work for node 12.
At least locally I get eslint issues pointing to

serverless/lib/plugins/aws/deploy/lib/check-for-changes.js

Line 73 in 767b9a5

const objects = result?.Contents?.filter(({ Key: key }) =>

[mnapoli]

Thanks!

And yes we can bump to Node 14 👍

[buddhaCode]

Are there any caveats using a steam response? Sounds like this feature is like paradise on earth. Timeouts up to 15 min and response size over 10MB?

[andidev]

I think no. Pricing is around the same as well (long time ago I checked it though)
Only thing is you need to change the implementation in the handler some and also on client side. It is a bit more tricky to manage the errors maybe.
Check with an AI.