feat(lambda-nodejs): allow passing env vars to container (#8169)

Add a `containerEnvironment` prop to pass environment variables to the
container running Parcel.

Closes #8031


----

*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

@@ -41,6 +41,17 @@ 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).
 
+Use the `containerEnvironment` prop to pass environments variables to the Docker container
+running Parcel:
+
+```ts
+new lambda.NodejsFunction(this, 'my-handler', {
+  containerEnvironment: {
+    NODE_ENV: 'production',
+  },
+});
+```
+
 ### Configuring Parcel
 The `NodejsFunction` construct exposes some [Parcel](https://parceljs.org/) options via properties: `minify`, `sourceMaps`,
 `buildDir` and `cacheDir`.

packages/@aws-cdk/aws-lambda-nodejs/lib/builder.ts

@@ -54,6 +54,13 @@ export interface BuilderOptions {
    * mounted in the Docker container.
    */
   readonly projectRoot: string;
+
+  /**
+   * The environment variables to pass to the container running Parcel.
+   *
+   * @default - no environment variables are passed to the container
+   */
+  readonly environment?: { [key: string]: string; };
 }
 
 /**
@@ -111,6 +118,7 @@ export class Builder {
         '-v', `${this.options.projectRoot}:${containerProjectRoot}`,
         '-v', `${path.resolve(this.options.outDir)}:${containerOutDir}`,
         ...(this.options.cacheDir ? ['-v', `${path.resolve(this.options.cacheDir)}:${containerCacheDir}`] : []),
+        ...flatten(Object.entries(this.options.environment || {}).map(([k, v]) => ['--env', `${k}=${v}`])),
         '-w', path.dirname(containerEntryPath).replace(/\\/g, '/'), // Always use POSIX paths in the container
         'parcel-bundler',
       ];
@@ -164,3 +172,7 @@ export class Builder {
     fs.writeFileSync(this.pkgPath, this.originalPkg);
   }
 }
+
+function flatten(x: string[][]) {
+  return Array.prototype.concat([], ...x);
+}

packages/@aws-cdk/aws-lambda-nodejs/lib/function.ts

@@ -84,6 +84,13 @@ export interface NodejsFunctionProps extends lambda.FunctionOptions {
    * @default - the closest path containing a .git folder
    */
   readonly projectRoot?: string;
+
+  /**
+   * The environment variables to pass to the container running Parcel.
+   *
+   * @default - no environment variables are passed to the container
+   */
+  readonly containerEnvironment?: { [key: string]: string; };
 }
 
 /**
@@ -119,6 +126,7 @@ export class NodejsFunction extends lambda.Function {
       nodeVersion: extractVersion(runtime),
       nodeDockerTag: props.nodeDockerTag || `${process.versions.node}-alpine`,
       projectRoot: path.resolve(projectRoot),
+      environment: props.containerEnvironment,
     });
     builder.build();
 

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

@@ -80,6 +80,30 @@ test('with Windows paths', () => {
   ]));
 });
 
+test('with env vars', () => {
+  const builder = new Builder({
+    entry: '/project/folder/entry.ts',
+    global: 'handler',
+    outDir: '/out-dir',
+    cacheDir: '/cache-dir',
+    nodeDockerTag: 'lts-alpine',
+    nodeVersion: '12',
+    projectRoot: '/project',
+    environment: {
+      KEY1: 'VALUE1',
+      KEY2: 'VALUE2',
+    },
+  });
+  builder.build();
+
+  // docker run
+  expect(spawnSync).toHaveBeenCalledWith('docker', expect.arrayContaining([
+    'run',
+    '--env', 'KEY1=VALUE1',
+    '--env', 'KEY2=VALUE2',
+  ]));
+});
+
 test('throws in case of error', () => {
   const builder = new Builder({
     entry: '/project/folder/error',

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

@@ -54,6 +54,21 @@ test('NodejsFunction with .js handler', () => {
   }));
 });
 
+test('NodejsFunction with container env vars', () => {
+  // WHEN
+  new NodejsFunction(stack, 'handler1', {
+    containerEnvironment: {
+      KEY: 'VALUE',
+    },
+  });
+
+  expect(Builder).toHaveBeenCalledWith(expect.objectContaining({
+    environment: {
+      KEY: 'VALUE',
+    },
+  }));
+});
+
 test('throws when entry is not js/ts', () => {
   expect(() => new NodejsFunction(stack, 'Fn', {
     entry: 'handler.py',