JSPM

Amazon Lambda Node.js Library

The APIs of higher level constructs in this module are experimental and under active development. They are subject to non-backward compatible changes or removal in any future version. These are not subject to the Semantic Versioning model and breaking changes will be announced in the release notes. This means that while you may use them, you may need to update your source code when upgrading to a newer version of this package.

This library provides constructs for Node.js Lambda functions.

To use this module, you will need to have Docker installed.

Node.js Function

Define a NodejsFunction:

new lambda.NodejsFunction(this, 'my-handler');

By default, the construct will use the name of the defining file and the construct's id to look up the entry file:

.
├── stack.ts # defines a 'NodejsFunction' with 'my-handler' as id
├── stack.my-handler.ts # exports a function named 'handler'

This file is used as "entry" for esbuild. This means that your code is automatically transpiled and bundled whether it's written in JavaScript or TypeScript.

Alternatively, an entry file and handler can be specified:

new lambda.NodejsFunction(this, 'MyFunction', {
  entry: '/path/to/my/file.ts', // accepts .js, .jsx, .ts and .tsx files
  handler: 'myExportedFunc'
});

All other properties of lambda.Function are supported, see also the AWS Lambda construct library.

The NodejsFunction construct automatically reuses existing connections when working with the AWS SDK for JavaScript. Set the awsSdkConnectionReuse prop to false to disable it.

Use the bundlingEnvironment prop to define environments variables when esbuild runs:

new lambda.NodejsFunction(this, 'my-handler', {
  bundlingEnvironment: {
    NODE_ENV: 'production',
  },
});

Use the buildArgs prop to pass build arguments when building the bundling image:

new lambda.NodejsFunction(this, 'my-handler', {
  buildArgs: {
    HTTPS_PROXY: 'https://127.0.0.1:3001',
  },
});

Use the bundlingDockerImage prop to use a custom bundling image:

new lambda.NodejsFunction(this, 'my-handler', {
  bundlingDockerImage: dk.BundlingDockerImage.fromAsset('/path/to/Dockerfile'),
});

This image should have esbuild installed globally. If you plan to use nodeModules it should also have npm or yarn depending on the lock file you're using.

Use the default image provided by @aws-cdk/aws-lambda-nodejs as a source of inspiration.

Lock file

The NodejsFunction requires a dependencies lock file (yarn.lock or package-lock.json). When bundling in a Docker container, the path containing this lock file is used as the source (/asset-input) for the volume mounted in the container.

By default, it will try to automatically determine your project lock file. Alternatively, you can specify the depsLockFilePath prop manually. In this case you need to ensure that this path includes entry and any module/dependencies used by your function. Otherwise bundling will fail.

Configuring esbuild

The NodejsFunction construct exposes some esbuild options via properties: minify, sourceMaps and target.

Working with modules

Externals

By default, all node modules are bundled except for aws-sdk. This can be configured by specifying the externalModules prop.

new lambda.NodejsFunction(this, 'my-handler', {
  externalModules: [
    'aws-sdk', // Use the 'aws-sdk' available in the Lambda runtime
    'cool-module', // 'cool-module' is already available in a Layer
  ],
});

Install modules

By default, all node modules referenced in your Lambda code will be bundled by esbuild. Use the nodeModules prop to specify a list of modules that should not be bundled but instead included in the node_modules folder of the Lambda package. This is useful when working with native dependencies or when esbuild fails to bundle a module.

new lambda.NodejsFunction(this, 'my-handler', {
  nodeModules: ['native-module', 'other-module']
});

The modules listed in nodeModules must be present in the package.json's dependencies. The same version will be used for installation. The lock file (yarn.lock or package-lock.json) will be used along with the right installer (yarn or npm).

Local bundling

If esbuild is available it will be used to bundle your code in your environment. Otherwise, bundling will happen in a Lambda compatible Docker container.

For macOS the recommendend approach is to install esbuild as Docker volume performance is really poor.

esbuild can be installed with:

$ npm install --save-dev esbuild@0

OR

$ yarn add --dev esbuild@0

To force bundling in a Docker container, set the forceDockerBundling prop to true. This is useful if your function relies on node modules that should be installed (nodeModules prop, see above) in a Lambda compatible environment. This is usually the case with modules using native dependencies.