feat(lambda-nodejs): support build args (aws#9035)

Add support for passing build arguments when building the bundling
image.

Closes aws#8117


----

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

packages/@aws-cdk/aws-lambda-nodejs/README.md

@@ -52,6 +52,15 @@ new lambda.NodejsFunction(this, 'my-handler', {
 });
 ```
 
+Use the `buildArgs` prop to pass build arguments when building the bundling image:
+```ts
+new lambda.NodejsFunction(this, 'my-handler', {
+  buildArgs: {
+    HTTPS_PROXY: 'https://127.0.0.1:3001',
+  },
+});
+```
+
 ### Configuring Parcel
 The `NodejsFunction` construct exposes some [Parcel](https://parceljs.org/) options via properties: `minify`, `sourceMaps` and `cacheDir`.
 

packages/@aws-cdk/aws-lambda-nodejs/lib/bundling.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 { PackageJsonManager } from './package-json-manager';
 import { findUp } from './util';
 
@@ -71,6 +71,13 @@ export interface ParcelBaseOptions {
    * @default - 2.0.0-beta.1
    */
   readonly parcelVersion?: string;
+
+  /**
+   * Build arguments to pass when building the bundling image.
+   *
+   * @default - no build arguments are passed
+   */
+  readonly buildArgs?: { [key:string] : string };
 }
 
 /**
@@ -105,6 +112,7 @@ export class Bundling {
     // Bundling image derived from runtime bundling image (lambci)
     const image = cdk.BundlingDockerImage.fromAsset(path.join(__dirname, '../parcel'), {
       buildArgs: {
+        ...options.buildArgs ?? {},
         IMAGE: options.runtime.bundlingDockerImage.image,
         PARCEL_VERSION: options.parcelVersion ?? '2.0.0-beta.1',
       },

packages/@aws-cdk/aws-lambda-nodejs/test/bundling.test.ts

@@ -1,9 +1,9 @@
 
-import { Code, Runtime } from '@aws-cdk/aws-lambda';
-import { AssetHashType } from '@aws-cdk/core';
-import { version as delayVersion } from 'delay/package.json';
 import * as fs from 'fs';
 import * as path from 'path';
+import { Code, Runtime } from '@aws-cdk/aws-lambda';
+import { AssetHashType, BundlingDockerImage } from '@aws-cdk/core';
+import { version as delayVersion } from 'delay/package.json';
 import { Bundling } from '../lib/bundling';
 import * as util from '../lib/util';
 
@@ -18,6 +18,7 @@ const findUpMock = jest.spyOn(util, 'findUp').mockImplementation((name: string,
   }
   return originalFindUp(name, directory);
 });
+const fromAssetMock = jest.spyOn(BundlingDockerImage, 'fromAsset');
 
 beforeEach(() => {
   jest.clearAllMocks();
@@ -157,3 +158,20 @@ test('Detects yarn.lock', () => {
     }),
   });
 });
+
+test('with build args', () => {
+  Bundling.parcel({
+    entry: '/project/folder/entry.ts',
+    runtime: Runtime.NODEJS_12_X,
+    projectRoot: '/project',
+    buildArgs: {
+      HELLO: 'WORLD',
+    },
+  });
+
+  expect(fromAssetMock).toHaveBeenCalledWith(expect.stringMatching(/parcel$/), expect.objectContaining({
+    buildArgs: expect.objectContaining({
+      HELLO: 'WORLD',
+    }),
+  }));
+});