fix: aws-cdk-lib imports from ESM modules are broken

packages/aws-cdk-lib/.gitignore

@@ -6,6 +6,9 @@
 !NOTICE
 !README.md
 !scripts/
+!scripts/*.ts
+!scripts/*.sh
+scripts/*.d.ts
 
 .LAST_BUILD
 *.snk

packages/aws-cdk-lib/.npmignore

@@ -36,3 +36,5 @@ junit.xml
 exports.d.ts
 exports.js
 exports.js.map
+
+scripts

packages/aws-cdk-lib/package.json

@@ -38,7 +38,6 @@
     "stripDeprecated": true,
     "compressAssembly": true,
     "post": [
-      "cp exports.js index.js",
       "node ./scripts/verify-imports-resolve-same.js",
       "node ./scripts/verify-imports-shielded.js",
       "/bin/bash ./scripts/minify-sources.sh"
@@ -407,7 +406,10 @@
     "excludeExperimentalModules": true
   },
   "exports": {
-    ".": "./index.js",
+    ".": {
+      "import": "./index.js",
+      "require": "./lazy-index.js"
+    },
     "./package.json": "./package.json",
     "./.jsii": "./.jsii",
     "./.warnings.jsii.js": "./.warnings.jsii.js",
@@ -481,6 +483,7 @@
     "./aws-dlm": "./aws-dlm/index.js",
     "./aws-dms": "./aws-dms/index.js",
     "./aws-docdb": "./aws-docdb/index.js",
+    "./aws-docdbelastic": "./aws-docdbelastic/index.js",
     "./aws-dynamodb": "./aws-dynamodb/index.js",
     "./aws-ec2": "./aws-ec2/index.js",
     "./aws-ecr": "./aws-ecr/index.js",
@@ -513,6 +516,7 @@
     "./aws-globalaccelerator": "./aws-globalaccelerator/index.js",
     "./aws-globalaccelerator-endpoints": "./aws-globalaccelerator-endpoints/index.js",
     "./aws-glue": "./aws-glue/index.js",
+    "./aws-grafana": "./aws-grafana/index.js",
     "./aws-greengrass": "./aws-greengrass/index.js",
     "./aws-greengrassv2": "./aws-greengrassv2/index.js",
     "./aws-groundstation": "./aws-groundstation/index.js",
@@ -537,6 +541,7 @@
     "./aws-ivs": "./aws-ivs/index.js",
     "./aws-kafkaconnect": "./aws-kafkaconnect/index.js",
     "./aws-kendra": "./aws-kendra/index.js",
+    "./aws-kendraranking": "./aws-kendraranking/index.js",
     "./aws-kinesis": "./aws-kinesis/index.js",
     "./aws-kinesisanalytics": "./aws-kinesisanalytics/index.js",
     "./aws-kinesisanalyticsv2": "./aws-kinesisanalyticsv2/index.js",
@@ -573,13 +578,17 @@
     "./aws-networkfirewall": "./aws-networkfirewall/index.js",
     "./aws-networkmanager": "./aws-networkmanager/index.js",
     "./aws-nimblestudio": "./aws-nimblestudio/index.js",
+    "./aws-oam": "./aws-oam/index.js",
+    "./aws-opensearchserverless": "./aws-opensearchserverless/index.js",
     "./aws-opensearchservice": "./aws-opensearchservice/index.js",
     "./aws-opsworks": "./aws-opsworks/index.js",
     "./aws-opsworkscm": "./aws-opsworkscm/index.js",
+    "./aws-organizations": "./aws-organizations/index.js",
     "./aws-panorama": "./aws-panorama/index.js",
     "./aws-personalize": "./aws-personalize/index.js",
     "./aws-pinpoint": "./aws-pinpoint/index.js",
     "./aws-pinpointemail": "./aws-pinpointemail/index.js",
+    "./aws-pipes": "./aws-pipes/index.js",
     "./aws-qldb": "./aws-qldb/index.js",
     "./aws-quicksight": "./aws-quicksight/index.js",
     "./aws-ram": "./aws-ram/index.js",
@@ -589,6 +598,7 @@
     "./aws-refactorspaces": "./aws-refactorspaces/index.js",
     "./aws-rekognition": "./aws-rekognition/index.js",
     "./aws-resiliencehub": "./aws-resiliencehub/index.js",
+    "./aws-resourceexplorer2": "./aws-resourceexplorer2/index.js",
     "./aws-resourcegroups": "./aws-resourcegroups/index.js",
     "./aws-robomaker": "./aws-robomaker/index.js",
     "./aws-rolesanywhere": "./aws-rolesanywhere/index.js",
@@ -607,6 +617,7 @@
     "./aws-s3outposts": "./aws-s3outposts/index.js",
     "./aws-sagemaker": "./aws-sagemaker/index.js",
     "./aws-sam": "./aws-sam/index.js",
+    "./aws-scheduler": "./aws-scheduler/index.js",
     "./aws-sdb": "./aws-sdb/index.js",
     "./aws-secretsmanager": "./aws-secretsmanager/index.js",
     "./aws-securityhub": "./aws-securityhub/index.js",

tools/@aws-cdk/ubergen/bin/ubergen.ts

@@ -47,6 +47,11 @@ interface LibraryReference {
   readonly shortName: string;
 }
 
+type Export = string | {
+  readonly import?: string;
+  readonly require?: string;
+};
+
 interface PackageJson {
   readonly main?: string;
   readonly description?: string;
@@ -103,7 +108,7 @@ interface PackageJson {
      */
     readonly exports?: Record<string, string>;
   };
-  exports?: Record<string, string>;
+  exports?: Record<string, Export>;
 }
 
 /**
@@ -269,7 +274,10 @@ async function prepareSourceFiles(libraries: readonly LibraryReference[], packag
   // Control 'exports' field of the 'package.json'. This will control what kind of 'import' statements are
   // allowed for this package: we only want to allow the exact import statements that we want to support.
   packageJson.exports = {
-    '.': './index.js',
+    '.': {
+      import: './index.js',
+      require: './lazy-index.js',
+    },
 
     // We need to expose 'package.json' and '.jsii' because 'jsii' and 'jsii-reflect' load them using
     // require(). (-_-). Can be removed after https://github.com/aws/jsii/pull/3205 gets merged.
@@ -281,12 +289,15 @@ async function prepareSourceFiles(libraries: readonly LibraryReference[], packag
   };
 
   // We use the index.ts to compile type definitions.
-  // At the very end we replace the compiled index.js file with our fixed version exports.js.
-  // exports.js has the top level submodules exports defined as a getter function,
-  // so they are not automatically loaded when importing from `aws-cdk-lib`.
+  //
+  // We build two indexes: one for eager loading (used by ESM modules), and one
+  // for lazy loading (used by CJS modules). The lazy loading will result in faster
+  // loading times, because we don't have to load and parse all submodules right away,
+  // but is not compatible with ESM's loading algorithm.
+  //
   // This improves AWS CDK app performance by ~400ms.
   const indexStatements = new Array<string>();
-  const exportsStatements = new Array<string>();
+  const lazyExports = new Array<string>();
 
   for (const library of libraries) {
     const libDir = path.join(libRoot, library.shortName);
@@ -297,19 +308,21 @@ async function prepareSourceFiles(libraries: readonly LibraryReference[], packag
     }
     if (library.shortName === 'core') {
       indexStatements.push(`export * from './${library.shortName}';`);
-      exportsStatements.unshift(`export * from './${library.shortName}';`);
+      lazyExports.unshift(`export * from './${library.shortName}';`);
     } else {
-      indexStatements.push(`export * as ${library.shortName.replace(/-/g, '_')} from './${library.shortName}';`);
-      exportsStatements.push(`Object.defineProperty(exports, '${library.shortName.replace(/-/g, '_')}', { get: function () { return require('./${library.shortName}'); } });`);
+      const exportName = library.shortName.replace(/-/g, '_');
+
+      indexStatements.push(`export * as ${exportName} from './${library.shortName}';`);
+      lazyExports.push(`Object.defineProperty(exports, '${exportName}', { get: function () { return require('./${library.shortName}'); } });`);
     }
     copySubmoduleExports(packageJson.exports, library, library.shortName);
   }
 
   // make the exports.ts file pass linting
-  exportsStatements.unshift('/* eslint-disable @typescript-eslint/no-require-imports */');
+  lazyExports.unshift('/* eslint-disable @typescript-eslint/no-require-imports */');
 
   await fs.writeFile(path.join(libRoot, 'index.ts'), indexStatements.join('\n'), { encoding: 'utf8' });
-  await fs.writeFile(path.join(libRoot, 'exports.ts'), exportsStatements.join('\n'), { encoding: 'utf8' });
+  await fs.writeFile(path.join(libRoot, 'lazy-index.ts'), lazyExports.join('\n'), { encoding: 'utf8' });
 
   console.log('\t🍺 Success!');
 }
@@ -320,13 +333,21 @@ async function prepareSourceFiles(libraries: readonly LibraryReference[], packag
  * Replace the original 'main' export with an export of the new '<submodule>/index.ts` file we've written
  * in 'transformPackage'.
  */
-function copySubmoduleExports(targetExports: Record<string, string>, library: LibraryReference, subdirectory: string) {
+function copySubmoduleExports(targetExports: Record<string, Export>, library: LibraryReference, subdirectory: string) {
   const visibleName = library.shortName;
 
   // Do both REAL "exports" section, as well as virtual, ubergen-only "exports" section
   for (const exportSet of [library.packageJson.exports, library.packageJson.ubergen?.exports]) {
     for (const [relPath, relSource] of Object.entries(exportSet ?? {})) {
-      targetExports[`./${unixPath(path.join(visibleName, relPath))}`] = `./${unixPath(path.join(subdirectory, relSource))}`;
+      targetExports[`./${unixPath(path.join(visibleName, relPath))}`] = resolveExport(relSource);
+    }
+  }
+
+  function resolveExport<A extends Export>(exp: A): A {
+    if (typeof exp === 'string') {
+      return `./${unixPath(path.join(subdirectory, exp))}` as any;
+    } else {
+      return Object.fromEntries(Object.entries(exp).map(([k, v]) => [k, v ? resolveExport(v) : undefined])) as any;
     }
   }