How to stream AWS Lambda response in node?

Question

I have an AWS Lambda function, and I need to invoke it from my node app and stream the result back to the client. I've looked in the docs but can't see a way. I want to do something like this:

lambda.invoke(params).then(data => data.pipe(res))

or even

lambda.invoke(params, (err, data) => {
  // data should be a pipeable stream instead of buffered
  data.pipe(res)
})

Answer 1

The Javascript AWS SDK supports streaming the body of the API responses so API calls like getting a large S3 blob of binary data can be streamed to Javascript functions.

lambda.invoke(lambdaDef)
  .createReadStream()
  .on('data', function(data) {
    console.log("Got data:", data.toString())
  })

You'll get the Payload of the response as data.

The Javascript lambda functions don't support any streaming options except for logging and inbound events, just a callback that returns a chunk of data.
The Java SDK does have a specific handler for streams -com.amazonaws.services.lambda.runtime.RequestStreamHandler.