Currently the AWS CDK only supports applets published as JavaScript modules.

Applets are files in the YAML or JSON format that have the following root attribute, where MODULE can represent a local file, such as ./my-module, a local dependency, such as my-dependency, or a global module, such as @aws-cdk/aws-s3 and CLASS is the name of a class exported by the module.

applet: MODULE[:CLASS]

If CLASS is not specified, Applet is used as the default class name. Therefore, you need only refer to AWS CDK construct libraries that export an Applet class by their library name.

The rest of the YAML file is applet-dependent. The object is passed as props when the applet object is instantiated and added to an AWS CDK app created by cdk-applet-js.

Use cdk-applet-js applet to run the applet, create an AWS CDK app, and use that with the AWS CDK tools, as shown in the following example.

cdk --app "cdk-applet-js ./my-applet.yaml" synth

To make the applet file executable and use the host as a shebang on Unix-based systems, such as Linux, MacOS, or Windows Bash shell, create a script similar to the following.

#!/usr/bin/env cdk-applet-js

applet: aws-cdk-codebuild
source: arn:aws:codecommit:::my-repository
image: node:8.9.4
compute: large
   - npm install --unsafe-perm
   - npm test
   - npm pack --unsafe-perm

To execute the applet and synthesize an AWS CloudFormation template, use the following command.

cdk synth --app "./build.yaml"

To avoid needing –app for every invocation, add the following entry to cdk.json.

   "app": "./build.yaml"