inject shim for cjs dependencies (#951)

* inject shim for cjs require

* add filename and dirname to cjs shim

Author: rtpascual

.changeset/lucky-lizards-tan.md

@@ -0,0 +1,5 @@
+---
+'@aws-amplify/backend-function': patch
+---
+
+Inject shim for cjs require for functions

packages/backend-function/src/cjs_shim.ts

@@ -0,0 +1,6 @@
+import { createRequire } from 'node:module';
+import path from 'node:path';
+import url from 'node:url';
+global.require = createRequire(import.meta.url);
+global.__filename = url.fileURLToPath(import.meta.url);
+global.__dirname = path.dirname(__filename);

packages/backend-function/src/factory.ts

@@ -13,7 +13,6 @@ import * as path from 'path';
 import { getCallerDirectory } from './get_caller_directory.js';
 import { Duration } from 'aws-cdk-lib';
 import { Runtime } from 'aws-cdk-lib/aws-lambda';
-
 import fs from 'fs';
 import { createRequire } from 'module';
 import { FunctionEnvironmentTranslator } from './function_env_translator.js';
@@ -246,6 +245,8 @@ class AmplifyFunction
       .replaceAll('\r', '')
       .split('//#')[0]; // remove source map
 
+    const cjsShimRequire = require.resolve('./cjs_shim');
+
     const functionLambda = new NodejsFunction(scope, `${id}-lambda`, {
       entry: props.entry,
       environment: environmentRecord as { [key: string]: string }, // for some reason TS can't figure out that this is the same as Record<string, string>
@@ -255,6 +256,7 @@ class AmplifyFunction
       bundling: {
         banner: bannerCode,
         format: OutputFormat.ESM,
+        inject: [cjsShimRequire], // replace require to fix dynamic require errors with cjs
       },
     });