New preset: aws-lambda streaming with REST API v1 support

[justcloudnative]

Idea

Add a new preset for AWS Lambda streaming that supports the REST API v1 (API Gateway) event format.

Context

The existing aws-lambda preset with streaming: true only supports the HTTP API v2 event format. AWS recently
added response streaming support to REST API v1 via responseTransferMode: "STREAM" in the OpenAPI integration
configuration, opening up Lambda streaming to REST API v1 users.

REST API v1 is still widely used because of features not available in HTTP API v2:

• AWS WAF integration
• Request validation
• API keys and usage plans
• Resource policies

What the new preset would do

Handle the REST API v1 event format in a streaming Lambda handler:

• Use event.path (v1) instead of event.rawPath (v2) for routing
• Use event.httpMethod (v1) instead of event.requestContext.http.method (v2)
• Include event.multiValueQueryStringParameters (v1 only) in the query object
• Stream responses using awslambda.streamifyResponse

Proposed changes

The change is in src/presets/aws-lambda/runtime/aws-lambda-streaming.ts:

 import type { Readable } from "node:stream";
-import type { APIGatewayProxyEventV2 } from "aws-lambda";
+import type {
+  APIGatewayProxyEvent,
+  APIGatewayProxyEventV2,
+} from "aws-lambda";
 import "#nitro-internal-pollyfills";
 import { useNitroApp } from "nitropack/runtime";
 import {
@@ -15,12 +17,19 @@ const nitroApp = useNitroApp();

 export const handler = awslambda.streamifyResponse(
-  async (event: APIGatewayProxyEventV2, responseStream, context) => {
+  async (
+    event: APIGatewayProxyEvent | APIGatewayProxyEventV2,
+    responseStream,
+    context,
+  ) => {
     const query = {
       ...event.queryStringParameters,
+      ...(event as APIGatewayProxyEvent).multiValueQueryStringParameters,
     };
-    const url = withQuery(event.rawPath, query);
-    const method = event.requestContext?.http?.method || "get";
+    const url = withQuery(
+      (event as APIGatewayProxyEvent).path ||
+        (event as APIGatewayProxyEventV2).rawPath,
+      query,
+    );
+    const method =
+      (event as APIGatewayProxyEvent).httpMethod ||
+      (event as APIGatewayProxyEventV2).requestContext?.http?.method ||
+      "get";

This aligns the streaming handler with the non-streaming handler (aws-lambda.ts) which already supports both v1 and
v2. The response handling (isApiGwV2 check, cookies, multiValueHeaders) already works for both formats — only
the request parsing needs updating.

[pi0]

Thanks for headsup. We are moving AWS support to srvx lambda do you mind to raise an issue in srvx + links to any announcement from AWS?

[justcloudnative]

I can do. Moving when?