feat(lambda-nodejs): connection reuse with aws-sdk

By default, the default Node.js HTTP/HTTPS agent creates a new TCP connection for every new request. To avoid the cost of establishing a new connection, configure the SDK for JavaScript to reuse TCP connections. For short-lived operations, such as DynamoDB queries, the latency overhead of setting up a TCP connection might be greater than the operation itself. See https://docs.aws.amazon.com/sdk-for-javascript/v2/developer-guide/node-reusing-connections.html
aws · Jul 15, 2020 · 229eff7 · 229eff7
1 parent b0f8729
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diff --git a/packages/@aws-cdk/aws-lambda-nodejs/README.md b/packages/@aws-cdk/aws-lambda-nodejs/README.md
@@ -41,6 +41,9 @@ new lambda.NodejsFunction(this, 'MyFunction', {
 
 All other properties of `lambda.Function` are supported, see also the [AWS Lambda construct library](https://github.com/aws/aws-cdk/tree/master/packages/%40aws-cdk/aws-lambda).
 
+The `NodejsFunction` construct automatically [reuses existing connections](https://docs.aws.amazon.com/sdk-for-javascript/v2/developer-guide/node-reusing-connections.html)
+when working with the AWS SDK for JavaScript.
+
 Use the `containerEnvironment` prop to pass environments variables to the Docker container
 running Parcel:
 

diff --git a/packages/@aws-cdk/aws-lambda-nodejs/lib/function.ts b/packages/@aws-cdk/aws-lambda-nodejs/lib/function.ts
@@ -1,7 +1,7 @@
-import * as lambda from '@aws-cdk/aws-lambda';
-import * as cdk from '@aws-cdk/core';
 import * as fs from 'fs';
 import * as path from 'path';
+import * as lambda from '@aws-cdk/aws-lambda';
+import * as cdk from '@aws-cdk/core';
 import { Bundling, ParcelBaseOptions } from './bundling';
 import { PackageJsonManager } from './package-json-manager';
 import { nodeMajorVersion, parseStackTrace } from './util';
@@ -69,6 +69,9 @@ export class NodejsFunction extends lambda.Function {
         }),
         handler: `index.${handler}`,
       });
+
+      // Enable connection reuse for aws-sdk
+      this.addEnvironment('AWS_NODEJS_CONNECTION_REUSE_ENABLED', '1');
     } finally {
       // We can only restore after the code has been bound to the function
       packageJsonManager.restore();

diff --git a/packages/@aws-cdk/aws-lambda-nodejs/test/function.test.ts b/packages/@aws-cdk/aws-lambda-nodejs/test/function.test.ts
@@ -1,8 +1,8 @@
 import '@aws-cdk/assert/jest';
-import { Runtime } from '@aws-cdk/aws-lambda';
-import { Stack } from '@aws-cdk/core';
 import * as fs from 'fs';
 import * as path from 'path';
+import { Runtime } from '@aws-cdk/aws-lambda';
+import { Stack } from '@aws-cdk/core';
 import { NodejsFunction } from '../lib';
 import { Bundling } from '../lib/bundling';
 
@@ -35,6 +35,11 @@ test('NodejsFunction with .ts handler', () => {
 
   expect(stack).toHaveResource('AWS::Lambda::Function', {
     Handler: 'index.handler',
+    Environment: {
+      Variables: {
+        AWS_NODEJS_CONNECTION_REUSE_ENABLED: '1',
+      },
+    },
   });
 });
 

diff --git a/packages/@aws-cdk/aws-lambda-nodejs/test/integ.dependencies.expected.json b/packages/@aws-cdk/aws-lambda-nodejs/test/integ.dependencies.expected.json
@@ -79,7 +79,12 @@
             "Arn"
           ]
         },
-        "Runtime": "nodejs12.x"
+        "Runtime": "nodejs12.x",
+        "Environment": {
+          "Variables": {
+            "AWS_NODEJS_CONNECTION_REUSE_ENABLED": "1"
+          }
+        }
       },
       "DependsOn": [
         "externalServiceRole85A00A90"