Introducing the AWS Cloud Development Kit

AWS CDK is an open-source framework that lets you create and provision AWS resources using code. At the time of writing, AWS CDK supports TypeScript, JavaScript, Python, Java, C#/.Net, and Go.

Key concepts

The AWS CDK is designed around a handful of important concepts. I will introduce a few of these here briefly.

An AWS CDK app is an application written in one of the languages mentioned above. An app defines one or more stacks. Stacks (Essentially AWS CloudFormation stacks). Stacks are comprised of Constructs which are cloud components (think Lambda Functions, S3 buckets, SQS queues etc).

The AWS CDK includes a CLI toolkit (Command Line Interface) for working with your AWS CDK apps. The CLI allows you to perform tasks such as:

• Convert AWS CDK stacks to AWS CloudFormation templates
• Deploy your stacks to an AWS account and Region

To install the toolkit you can simply use the following command:

npm install -g aws-cdk

And then you can use the toolkit to create a new typescript project:

• Template - can be app, lib and sample-app
• Language - can be TypeScript, JavaScript, Python, Java, C#/.Net, and Go.

cdk init template --language language

For a full list of commands that are contained in the CLI you can just use:

cdk help

Constructs

The AWS CDK includes a library of AWS constructs. Each AWS service is represented by a construct. Constructs are defined by levels. There are 3 levels:

L1 (Level 1)

These constructs correspond directly to resource types defined by AWS CloudFormation. These constructs are prefixed with Cfn before the construct name.

An example L1 construct:

// The code below shows an example of how to instantiate this type.
// The values are placeholders you should change.
import { aws_apigateway as apigateway } from 'aws-cdk-lib';
const cfnApiKey = new apigateway.CfnApiKey(
  this,
  'MyCfnApiKey',
  /* all optional props */ {
    customerId: 'customerId',
    description: 'description',
    enabled: false,
    generateDistinctId: false,
    name: 'name',
    stageKeys: [
      {
        restApiId: 'restApiId',
        stageName: 'stageName',
      },
    ],
    tags: [
      {
        key: 'key',
        value: 'value',
      },
    ],
    value: 'value',
  },
);

L2 (Level 2)

These constructs are developed by the AWS CDK team for specific use cases and make it easier to create simple infrastructure. L2 constructs (in most cases) encapsulate L1 resources.

An example L2 construct:

this.api = new apigateway.RestApi(this, 'ApiGatewayRestApi', {
  defaultCorsPreflightOptions: {
    allowOrigins: apigateway.Cors.ALL_ORIGINS,
    allowMethods: apigateway.Cors.ALL_METHODS,
  },
});

this.api.root.addMethod(
  'POST',
  new apigateway.LambdaIntegration(this.lambdaFunction, {
    proxy: true,
  }),
);

L3 (Level 3)

Level 3 constructs are patterns. These constructs allow easy configuration of resources, grant permissions etc.

An example L3 construct:

const restApi = new apigateway.LambdaRestApi(this, 'LambdaRestApiL3', {
  handler: this.lambdaFunction,
  defaultCorsPreflightOptions: {
    allowOrigins: apigateway.Cors.ALL_ORIGINS,
    allowMethods: apigateway.Cors.ALL_METHODS,
  },
});

This is only a small introduction to constructs. You can find more examples in the api docs or construct hub

Getting started

Installing the CDK via npm:

npm install -g aws-cdk

Verify the installation:

cdk help

Bootstrapping the environment:

cdk bootstrap aws://aws-acccount-number/aws-region

Bootstrapping is the process of provisioning resources for the AWS CDK before you can deploy AWS CDK apps into an AWS environment.

Create a new app:

cdk init app --language typescript

Deploy the stack:

cdk deploy

I hope you enjoyed the article which is a small introduction to the AWS CDK. There's plenty of information that I didn't cover here. You can read more about the AWS CDK here