Update AWS Lambda docs with streaming support

e2e/tests/aws-lambda.ts

@@ -69,7 +69,7 @@ export const awsLambdaDeployment: DeploymentConfiguration<{
       'func',
       {
         role: lambdaRole.arn,
-        runtime: 'nodejs18.x',
+        runtime: 'nodejs20.x',
         handler: 'index.handler',
         code: new pulumi.asset.AssetArchive({
           'index.js': new pulumi.asset.FileAsset(

examples/aws-lambda/.gitignore

@@ -2,6 +2,7 @@
 !scripts/*.js
 !jest.config.js
 *.d.ts
+!awslambda.d.ts
 node_modules
 
 # CDK asset staging directory

examples/aws-lambda/lambda/awslambda.d.ts

@@ -0,0 +1,28 @@
+import { Writable } from 'node:stream';
+import { APIGatewayEvent, Context, Handler } from 'aws-lambda';
+
+declare global {
+  namespace awslambda {
+    export namespace HttpResponseStream {
+      function from(
+        responseStream: ResponseStream,
+        metadata: {
+          statusCode?: number;
+          headers?: Record<string, string>;
+        },
+      ): ResponseStream;
+    }
+
+    export type ResponseStream = Writable & {
+      setContentType(type: string): void;
+    };
+
+    export type StreamifyHandler = (
+      event: APIGatewayEvent,
+      responseStream: ResponseStream,
+      context: Context,
+    ) => Promise<unknown>;
+
+    export function streamifyResponse(handler: StreamifyHandler): Handler<APIGatewayEvent>;
+  }
+}

examples/aws-lambda/lambda/graphql.ts

@@ -1,4 +1,5 @@
-import { APIGatewayEvent, APIGatewayProxyResult, Context } from 'aws-lambda';
+import { pipeline } from 'stream/promises';
+import { APIGatewayEvent, Context } from 'aws-lambda';
 import { createSchema, createYoga } from 'graphql-yoga';
 
 const yoga = createYoga<{
@@ -21,33 +22,45 @@ const yoga = createYoga<{
   }),
 });
 
-export async function handler(
-  event: APIGatewayEvent,
-  lambdaContext: Context,
-): Promise<APIGatewayProxyResult> {
-  const response = await yoga.fetch(
-    event.path +
-      '?' +
-      new URLSearchParams((event.queryStringParameters as Record<string, string>) || {}).toString(),
-    {
-      method: event.httpMethod,
-      headers: event.headers as HeadersInit,
-      body: event.body
-        ? Buffer.from(event.body, event.isBase64Encoded ? 'base64' : 'utf8')
-        : undefined,
-    },
-    {
-      event,
-      lambdaContext,
-    },
-  );
+export const handler = awslambda.streamifyResponse(
+  async function handler(event, res, lambdaContext) {
+    const response = await yoga.fetch(
+      // Construct the URL
+      event.path +
+        '?' +
+        // Parse query string parameters
+        new URLSearchParams(
+          (event.queryStringParameters as Record<string, string>) || {},
+        ).toString(),
+      {
+        method: event.httpMethod,
+        headers: event.headers as HeadersInit,
+        // Parse the body
+        body: event.body
+          ? Buffer.from(event.body, event.isBase64Encoded ? 'base64' : 'utf8')
+          : undefined,
+      },
+      {
+        event,
+        lambdaContext,
+        res,
+      },
+    );
+
+    // Create the metadata object for the response
+    const metadata = {
+      statusCode: response.status,
+      headers: Object.fromEntries(response.headers.entries()),
+    };
 
-  const responseHeaders = Object.fromEntries(response.headers.entries());
+    // Attach the metadata to the response stream
+    const resWithMetadata = awslambda.HttpResponseStream.from(res, metadata);
 
-  return {
-    statusCode: response.status,
-    headers: responseHeaders,
-    body: await response.text(),
-    isBase64Encoded: false,
-  };
-}
+    // Pipe the response body to the response stream
+    if (response.body) {
+      await pipeline(response.body, resWithMetadata);
+    } else {
+      resWithMetadata.end();
+    }
+  },
+);

examples/aws-lambda/lib/graphql-lambda-stack.ts

@@ -10,7 +10,7 @@ export class GraphqlLambdaStack extends cdk.Stack {
     const graphqlLambda = new lambda.Function(this, 'graphqlLambda', {
       code: lambda.Code.fromAsset(path.join(__dirname, '../lambda')),
       handler: 'graphql.handler',
-      runtime: lambda.Runtime.NODEJS_14_X,
+      runtime: lambda.Runtime.NODEJS_20_X,
     });
 
     new apiGateway.LambdaRestApi(this, 'graphqlEndpoint', {

examples/aws-lambda/package.json

@@ -22,13 +22,10 @@
     "source-map-support": "^0.5.16"
   },
   "devDependencies": {
-    "@aws-cdk/assert": "2.68.0",
-    "@types/aws-lambda": "8.10.116",
+    "@types/aws-lambda": "8.10.140",
     "@types/node": "18.16.16",
     "aws-cdk": "2.83.0",
-    "aws-cdk-lib": "2.83.0",
     "esbuild": "0.17.19",
-    "ts-node": "10.9.1",
     "typescript": "5.5.3"
   }
 }