feat(esbuild): implement first version of construct using esbuild

src/index.ts

@@ -1,42 +1,91 @@
 import * as lambda from '@aws-cdk/aws-lambda';
 import * as cdk from '@aws-cdk/core';
+import * as es from 'esbuild';
+import * as path from 'path';
 
-import { nodeMajorVersion } from './utils';
+import { extractFileName, findProjectRoot, nodeMajorVersion } from './utils';
 
+/**
+ * Properties for a NodejsFunction
+ */
 export interface NodejsFunctionProps extends lambda.FunctionOptions {
   /**
-   * The name of the exported handler in the entry file.
+   * The root of the lambda project. If you specify this prop, ensure that
+   * this path includes `entry` and any module/dependencies used by your
+   * function otherwise bundling will not be possible.
    *
-   * @default "handler"
+   * @default = the closest path containing a .git folder
+   */
+  readonly rootDir?: string;
+
+  /**
+   * The name of the method within your code that Lambda calls to execute your function.
+   *
+   * The format includes the file name and handler function.
+   * For more information, see https://docs.aws.amazon.com/lambda/latest/dg/lambda-nodejs.html.
+   *
+   * @default = 'index.handler'
    */
   readonly handler?: string;
+
   /**
    * The runtime environment. Only runtimes of the Node.js family are
    * supported.
    *
-   * @default - `NODEJS_12_X` if `process.versions.node` >= '12.0.0',
+   * @default = `NODEJS_12_X` if `process.versions.node` >= '12.0.0',
    * `NODEJS_10_X` otherwise.
    */
   readonly runtime?: lambda.Runtime;
+
+  /**
+   * The esbuild bundler specific options.
+   *
+   * @default = { platform: 'node' }
+   */
+  readonly esbuildOptions?: es.BuildOptions;
 }
 
+const BUILD_FOLDER = '.build';
+const DEFAULT_BUILD_OPTIONS: es.BuildOptions = {
+  bundle: true,
+  target: 'es2017',
+  external: ['aws-sdk'],
+};
+
+/**
+ * A Node.js Lambda function bundled using `esbuild`
+ */
 export class NodejsFunction extends lambda.Function {
   constructor(scope: cdk.Construct, id: string, props: NodejsFunctionProps = {}) {
     if (props.runtime && props.runtime.family !== lambda.RuntimeFamily.NODEJS) {
       throw new Error('Only `NODEJS` runtimes are supported.');
     }
 
-    const handler = props.handler ?? 'handler';
+    const projectRoot = findProjectRoot(props.rootDir);
+    if (!projectRoot) {
+      throw new Error('Cannot find root directory. Please specify it with `rootDir` option.');
+    }
+
+    const handler = props.handler ?? 'index.handler';
     const defaultRunTime = nodeMajorVersion() >= 12
       ? lambda.Runtime.NODEJS_12_X
       : lambda.Runtime.NODEJS_10_X;
     const runtime = props.runtime ?? defaultRunTime;
+    const entry = extractFileName(projectRoot, handler);
+
+    es.buildSync({
+      ...DEFAULT_BUILD_OPTIONS,
+      ...props.esbuildOptions,
+      entryPoints: [entry],
+      outdir: path.join(projectRoot, BUILD_FOLDER, path.dirname(entry)),
+      platform: 'node',
+    });
 
     super(scope, id, {
       ...props,
       runtime,
-      code: lambda.Code.fromInline('TODO'),
-      handler: `index.${handler}`,
+      code: lambda.Code.fromAsset(path.join(projectRoot, BUILD_FOLDER)),
+      handler,
     });
   }
 }

src/utils.ts

@@ -1,3 +1,53 @@
+import * as fs from 'fs-extra';
+import * as path from 'path';
+
+export function extractFileName(cwd: string, handler: string): string {
+  const fnName = path.extname(handler);
+  const fnNameLastAppearanceIndex = handler.lastIndexOf(fnName);
+  // replace only last instance to allow the same name for file and handler
+  const fileName = handler.substring(0, fnNameLastAppearanceIndex);
+
+  // Check if the .ts files exists. If so return that to watch
+  if (fs.existsSync(path.join(cwd, fileName + '.ts'))) {
+    return fileName + '.ts';
+  }
+
+  // Check if the .js files exists. If so return that to watch
+  if (fs.existsSync(path.join(cwd, fileName + '.js'))) {
+    return fileName + '.js';
+  }
+
+  // Can't find the files. Watch will have an exception anyway. So throw one with error.
+  console.log(`Cannot locate handler - ${fileName} not found`);
+  throw new Error('Compilation failed. Please ensure handler exists with ext .ts or .js');
+}
+
+/**
+ * Find a file by walking up parent directories
+ */
+export function findUp(name: string, directory: string = process.cwd()): string | undefined {
+  const absoluteDirectory = path.resolve(directory);
+
+  if (fs.existsSync(path.join(directory, name))) {
+    return directory;
+  }
+
+  const { root } = path.parse(absoluteDirectory);
+  if (absoluteDirectory === root) {
+    return undefined;
+  }
+
+  return findUp(name, path.dirname(absoluteDirectory));
+}
+
+export function findProjectRoot(rootDir: string): string {
+  return rootDir
+    ?? findUp(`.git${path.sep}`)
+    ?? findUp('yarn.lock')
+    ?? findUp('package-lock.json')
+    ?? findUp('package.json');
+}
+
 /**
  * Returns the major version of node installation
  */

tsconfig.json

@@ -1,14 +1,17 @@
 {
   "compilerOptions": {
-    "module": "commonjs",
+    "module": "CommonJS",
     "target": "es6",
+    "outDir": "dist",
+    "declaration": true,
     "skipLibCheck": true,
-    "outDir": "dist"
+    "esModuleInterop": true,
+    "lib": ["ES2017"]
   },
-  "include": [
-    "src"
-  ],
   "exclude": [
     "node_modules"
+  ],
+  "include": [
+    "src"
   ]
 }