AWS CDK

Use the AWS CDK (Cloud Development Kit) with LocalStack

2 minute read

Overview

The AWS Cloud Development Kit (CDK) is an Infrastructure-as-Code (IaC) tool using general-purpose programming languages such as TypeScript/JavaScript, Python, Java, and .NET to programmatically define your cloud architecture on AWS.

AWS CDK CLI for LocalStack

cdklocal is a thin wrapper script for using the AWS CDK library against local APIs provided by LocalStack.

Installation

The cdklocal command line is published as an npm library:

# Install globally
npm install -g aws-cdk-local aws-cdk

# Verify it installed correctly
cdklocal --version
# e.g. 1.65.5

Note

Using cdklocal locally (e.g. within the node_modules of your repo instead of globally installed) does not work at the moment for some setups, so make sure you install both aws-cdk and aws-cdk-local with the -G flag.

Usage

cdklocal can be used as a drop-in replacement of where you would otherwise use cdk when targeting the AWS Cloud.

$ cdklocal --help

Configuration

The following environment variables can be configured:

EDGE_PORT: Port under which LocalStack edge service is accessible (default: 4566)
LOCALSTACK_HOSTNAME: Target host under which LocalStack edge service is accessible (default: localhost)
LAMBDA_MOUNT_CODE: Whether to use local Lambda code mounting (via setting hot-reload S3 bucket name)

Example

Make sure that LocalStack is installed and successfully started with the required services before running the example

$ curl http://localhost:4566/_localstack/health

The CDK command line ships with a sample app generator to run a quick test for getting started.

# create sample app
mkdir /tmp/test; cd /tmp/test
cdklocal init sample-app --language=javascript

# deploy the sample app
cdklocal deploy
> Do you wish to deploy these changes (y/n)? y

Once the deployment is done, you can inspect the created resources via the awslocal command line

$ awslocal sns list-topics
 {
     "Topics": [
         {
             "TopicArn": "arn:aws:sns:us-east-1:000000000000:TestStack-TestTopic339EC197-79F43WWCCS4Z"
         }
     ]
}

Limitations

Stacks with validated certificates

By default, stacks with validated certificates may not be deployed using the local lambda executor. This originates from the way how CDK ensures the certificate is ready - it creates a single-file lambda function with a single dependency on aws-sdk which is usually preinstalled and available globally in lambda runtime. When this lambda is executed locally from the /tmp folder, the package can not be discovered by Node due to the way how Node package resolution works.