feat(aws-lambda-nodejs): add esbuild define bundling option

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

@@ -143,6 +143,9 @@ new lambda.NodejsFunction(this, 'my-handler', {
     loader: { // Use the 'dataurl' loader for '.png' files
       '.png': 'dataurl',
     },
+    define: { // Replace strings during build time
+      'process.env.API_KEY': JSON.stringify('xxx-xxxx-xxx'),
+    },
     logLevel: LogLevel.SILENT, // defaults to LogLevel.WARNING
     keepNames: true, // defaults to false
     tsconfig: 'custom-tsconfig.json' // use custom-tsconfig.json instead of default, 

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

@@ -136,6 +136,7 @@ export class Bundling implements cdk.BundlingOptions {
 
     const npx = osPlatform === 'win32' ? 'npx.cmd' : 'npx';
     const loaders = Object.entries(this.props.loader ?? {});
+    const defines = Object.entries(this.props.define ?? {});
 
     const esbuildCommand: string = [
       npx, 'esbuild',
@@ -147,6 +148,7 @@ export class Bundling implements cdk.BundlingOptions {
       ...this.props.sourceMap ? ['--sourcemap'] : [],
       ...this.externals.map(external => `--external:${external}`),
       ...loaders.map(([ext, name]) => `--loader:${ext}=${name}`),
+      ...defines.map(([key, value]) => `--define:${key}=${value}`),
       ...this.props.logLevel ? [`--log-level=${this.props.logLevel}`] : [],
       ...this.props.keepNames ? ['--keep-names'] : [],
       ...this.relativeTsconfigPath ? [`--tsconfig=${pathJoin(inputDir, this.relativeTsconfigPath)}`] : [],

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

@@ -138,6 +138,16 @@ export interface BundlingOptions {
    */
   readonly environment?: { [key: string]: string; };
 
+  /**
+   * Replace global identifiers with constant expressions.
+   *
+   * @example { 'process.env.DEBUG': 'true' }
+   * @example { 'process.env.API_KEY': JSON.stringify('xxx-xxxx-xxx') }
+   *
+   * @default - no replacements are made
+   */
+  readonly define?: { [key: string]: string };
+
   /**
    * A list of modules that should be considered as externals (already available
    * in the runtime).

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

@@ -168,6 +168,10 @@ test('esbuild bundling with esbuild options', () => {
     banner: '/* comments */',
     footer: '/* comments */',
     forceDockerBundling: true,
+    define: {
+      'DEBUG': 'true',
+      'process.env.KEY': JSON.stringify('VALUE'),
+    },
   });
 
   // Correctly bundles with esbuild
@@ -180,6 +184,7 @@ test('esbuild bundling with esbuild options', () => {
           'npx esbuild --bundle /asset-input/lib/handler.ts',
           '--target=es2020 --platform=node --outfile=/asset-output/index.js',
           '--minify --sourcemap --external:aws-sdk --loader:.png=dataurl',
+          '--define:DEBUG=true --define:process.env.KEY="VALUE"',
           '--log-level=silent --keep-names --tsconfig=/asset-input/lib/custom-tsconfig.ts',
           '--metafile=/asset-output/index.meta.json --banner=\'/* comments */\' --footer=\'/* comments */\'',
         ].join(' '),