fix handling of ESM modules

Author: matuscongrady

_test-stacks/provisioned-lambda/stacktape.ts

@@ -11,11 +11,10 @@ export default defineConfig(() => {
         enabled: true
       }
     },
-    runtime: 'nodejs24.x',
     provisionedConcurrency: 1
   });
 
   return {
-    resources: { lambda },
+    resources: { lambda }
   };
 });

src/config/random.ts

@@ -75,6 +75,7 @@ export const SENTRY_CAPTURE_EXCEPTION_WAIT_TIME_MS = 1500;
 export const DEFAULT_MAXIMUM_PARALLEL_ARTIFACT_UPLOADS = 10;
 export const DEFAULT_MAXIMUM_PARALLEL_BUCKET_SYNCS = 10;
 export const DEFAULT_CONTAINER_NODE_VERSION = 24;
+export const DEFAULT_LAMBDA_NODE_VERSION = 24;
 
 // @todo
 export const linksMap = {

src/domain/config-manager/index.ts

@@ -1,3 +1,4 @@
+import type { CfResourceTransform, FinalTransform } from './transforms-resolver';
 import { isAbsolute, join } from 'node:path';
 import { eventManager } from '@application-services/event-manager';
 import { globalStateManager } from '@application-services/global-state-manager';
@@ -26,6 +27,7 @@ import { getApexDomain } from '@utils/domains';
 import { getConfigPath } from '@utils/file-loaders';
 import { builtInDirectives } from './built-in-directives';
 import { ConfigResolver } from './config-resolver';
+import { TransformsResolver } from './transforms-resolver';
 import { getAlarmsToBeAppliedToResource, isGlobalAlarmEligibleForStack } from './utils/alarms';
 import { DEFAULT_TEST_LISTENER_PORT } from './utils/application-load-balancers';
 import { getStacktapeOriginRequestLambdaIamStatement } from './utils/iam';
@@ -41,7 +43,6 @@ import {
 } from './utils/lambdas';
 import { cleanConfigForMinimalTemplateCompilerMode, mergeStacktapeDefaults } from './utils/misc';
 import { runInitialValidations, validateConfigStructure } from './utils/validation';
-import { CfResourceTransform, FinalTransform, TransformsResolver } from './transforms-resolver';
 
 export class ConfigManager {
   config: StacktapeConfig;
@@ -76,7 +77,9 @@ export class ConfigManager {
     if (shouldLoadConfig) {
       // Only load transforms for TypeScript configs with defineConfig pattern
       if (this.transformsResolver.isDefineConfigStyle(globalStateManager.configPath)) {
-        const { transforms, finalTransform } = await this.transformsResolver.loadTransforms(globalStateManager.configPath);
+        const { transforms, finalTransform } = await this.transformsResolver.loadTransforms(
+          globalStateManager.configPath
+        );
         this.transforms = transforms;
         this.finalTransform = finalTransform;
       }
@@ -274,7 +277,8 @@ export class ConfigManager {
         handler: getLambdaHandler({ name, packaging }),
         resourceName: awsResourceNames.lambda(name, globalStateManager.targetStack.stackName),
         cfLogicalName: cfLogicalNames.lambda(name),
-        aliasLogicalName: (definition.deployment || definition.provisionedConcurrency) && cfLogicalNames.lambdaStpAlias(name),
+        aliasLogicalName:
+          (definition.deployment || definition.provisionedConcurrency) && cfLogicalNames.lambdaStpAlias(name),
         events: definition.events || [],
         configParentResourceType: 'function'
       } as StpLambdaFunction;

src/domain/packaging-manager/index.ts

@@ -1,6 +1,7 @@
 import { join } from 'node:path';
 import { eventManager } from '@application-services/event-manager';
 import { globalStateManager } from '@application-services/global-state-manager';
+import { DEFAULT_CONTAINER_NODE_VERSION, DEFAULT_LAMBDA_NODE_VERSION } from '@config';
 import { configManager } from '@domain-services/config-manager';
 import { deployedStackOverviewManager } from '@domain-services/deployed-stack-overview-manager';
 import { deploymentArtifactManager } from '@domain-services/deployment-artifact-manager';
@@ -368,16 +369,23 @@ export class PackagingManager {
         case 'jsx':
         case 'mjs':
         case 'tsx': {
-          // Extract Node.js version from runtime (e.g., 'nodejs24.x' -> '24')
-          const nodeVersion = runtime?.match(/nodejs(\d+)/)?.[1] || '22';
-          const useEsm = Number(nodeVersion) >= 24;
+          const languageSpecificConfig =
+            (packaging.properties.languageSpecificConfig as EsLanguageSpecificConfig) || undefined;
+          const nodeVersionFromRuntime = Number(runtime?.match(/nodejs(\d+)/)?.[1]) || null;
+          const nodeVersionFromUser = languageSpecificConfig?.nodeVersion;
+          const nodeVersion =
+            packagingType === 'stacktape-image-buildpack'
+              ? nodeVersionFromUser || DEFAULT_CONTAINER_NODE_VERSION
+              : nodeVersionFromUser || nodeVersionFromRuntime || DEFAULT_LAMBDA_NODE_VERSION;
+          const useEsm = languageSpecificConfig?.outputModuleFormat === 'esm' || nodeVersion >= 24;
+          console.log('useEsm', useEsm);
           const sharedStpBuildpackProps = {
             ...packaging.properties,
-            nodeTarget: nodeVersion,
             minify: false,
             keepNames: true,
+            nodeTarget: String(nodeVersion),
             entryfilePath: join(globalStateManager.workingDir, packaging.properties.entryfilePath),
-            // Node.js 24+ requires (and properly supports) ESM for proper default export handling
+            // Node.js 24+ on lambda only works with ESM. It has interoperability with CJS, so we always use ESM
             ...(useEsm && { outputModuleFormat: 'esm' as const })
           };
           const additionalDigestInput = objectHash(sharedStpBuildpackProps);