feat(apigateway): support response streaming with response transfer mode #36155

go-to-k · 2025-11-22T14:04:47Z

Issue # (if applicable)

Reason for this change

AWS announced support for response streaming in Amazon API Gateway to significantly improve the responsiveness of your REST APIs by progressively streaming response payloads back to the client.

see: https://aws.amazon.com/blogs/compute/building-responsive-apis-with-amazon-api-gateway-response-streaming/

This feature uses the responseTransferMode parameter for integrations.

see: https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-properties-apigateway-method-integration.html#cfn-apigateway-method-integration-responsetransfermode

Description of changes

Added responseTransferMode to IntegrationOptions.

Also, in the case of Lambda integrations, the URI path changes for streams (for example: arn:aws:apigateway:${APIGW_REGION}:lambda:path/2021-11-15/functions/${FN_ARN}/response-streaming-invocations), so I changed that in LambdaIntegration as well.

    const path = options.responseTransferMode === ResponseTransferMode.STREAM
      ? `2021-11-15/functions/${handler.functionArn}/response-streaming-invocations`
      : `2015-03-31/functions/${handler.functionArn}/invocations`;

ref:

https://docs.aws.amazon.com/lambda/latest/api/API_InvokeWithResponseStream.html#API_InvokeWithResponseStream_RequestSyntax
https://aws.amazon.com/jp/blogs/compute/building-responsive-apis-with-amazon-api-gateway-response-streaming/#:~:text=Setting%20response%20transfer%20mode%20using%20infrastructure%2Das%2Dcode%20(IaC)%20frameworks%2C%20such%20as%20AWS%20CloudFormation.%20Note%20the%20/response%2Dstreaming%2Dinvocations%20Uri%20fragment%2C%20it%20tells%20API%20Gateway%20to%20use%20the%20Lambda%20InvokeWithResponseStreaming%20endpoint%3A
- Note the /response-streaming-invocations Uri fragment, it tells API Gateway to use the Lambda [InvokeWithResponseStreaming](https://docs.aws.amazon.com/lambda/latest/api/API_InvokeWithResponseStream.html) endpoint:

Describe any new or updated permissions being added

Description of how you validated changes

Both unit tests and integ tests.

Checklist

My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

aws-cdk-automation

(This review is outdated)

✅ Updated pull request passes all PRLinter validations. Dismissing previous PRLinter review.

go-to-k · 2025-11-22T16:09:43Z

packages/aws-cdk-lib/aws-apigateway/lib/integration.ts

+    if (
+      options.responseTransferMode === ResponseTransferMode.STREAM &&
+      ![IntegrationType.AWS_PROXY, IntegrationType.HTTP_PROXY].includes(props.type)
+    ) {
+      throw new UnscopedValidationError(`ResponseTransferMode STREAM is only supported for AWS_PROXY and HTTP_PROXY integration types, got: ${props.type}`);
+    }


Otherwise the following errors occur.

ResponseTransferMode STREAM is not supported for AWS IntegrationType

ResponseTransferMode STREAM is not supported for HTTP IntegrationType

ResponseTransferMode STREAM is not supported for MOCK IntegrationType

ref: https://docs.aws.amazon.com/apigateway/latest/developerguide/response-transfer-mode.html#response-transfer-mode-considerations

You can only use response payload streaming for HTTP_PROXY or AWS_PROXY integration types.

alvazjor

Nice, thanks for the contribution

mergify · 2025-11-25T14:11:48Z

mergify · 2025-11-25T14:11:49Z