NpmLayerVersion

NpmLayerVersion is a CDK construct to create a custom lambda layer from an NPM package.json file.

Usage

Add the packages to be included in a package.json, and the construct will make sure they're up-to-date before every deployment (i.e. npm install), and generate the LayerVersion to use in your CDK stacks.

Directory Structure

NpmLayerVersion requires the following directory structure, as specified by AWS Lambda layer path configuration

<root>
|- <custom code>
|- nodejs
   |- package.json
   |- package-lock.json

Creating an NpmLayerVersion

You can create an NpmLayerVersion with the following NpmLayerVersionProps:

1. Path to the directory structure of the layer, relative to your tsconfig.json
2. Custom LayerVersionProps to pass to the underlying CDK LayerVersion construct:

const layer = new NpmLayerVersion(this, 'DependencyLayer', {
  layerPath: 'src/deploy/layer',
  layerVersionProps: {
    removalPolicy: UserApiStack.removalPolicy,
    compatibleArchitectures: [lambda.Architecture.ARM_64],
    compatibleRuntimes: [lambda.Runtime.NODEJS_16_X]
  }
});

Using with NodejsFunction

NpmLayerVersion provides two properties to be used when creating NodejsFunctions:

1. layerVersion: the underlying CDK LayerVersion representing the lambda layer itself
2. packagedDependencies: list of dependencies that were packaged.

The example below shows how to use this with NodejsFunctionProps:

const lambdaProps: NodejsFunctionProps = {
  architecture: lambda.Architecture.ARM_64,
  runtime: lambda.Runtime.NODEJS_16_X,
  bundling: {
    minify: false,
    target: 'node16',
    externalModules: layer.packagedDependencies // don't bundle layer dependencies in lambda
  },
  layers: [layer.layerVersion] // use lambda layer
};

Contributing

We're happy to accept contributions! Please open an issue before sending a PR to discuss proposed changes.