Work with the AWS CDK library

TypeScript supports importing either an entire namespace, or individual objects from a namespace. Each namespace includes constructs and other classes for use with a given AWS service.

// Import main CDK library as cdk
import * as cdk from 'aws-cdk-lib';   // ES6 import preferred in TS
const cdk = require('aws-cdk-lib');   // Node.js require() preferred in JS

// Import specific core CDK classes
import { Stack, App } from 'aws-cdk-lib';
const { Stack, App } = require('aws-cdk-lib');

// Import AWS S3 namespace as s3 into current namespace
import { aws_s3 as s3 } from 'aws-cdk-lib';   // TypeScript
const s3 = require('aws-cdk-lib/aws-s3');     // JavaScript

// Having imported cdk already as above, this is also valid
const s3 = cdk.aws_s3;

// Now use s3 to access the S3 types
const bucket = s3.Bucket(...);

// Selective import of s3.Bucket
import { Bucket } from 'aws-cdk-lib/aws-s3';        // TypeScript
const { Bucket } = require('aws-cdk-lib/aws-s3');   // JavaScript

// Now use Bucket to instantiate an S3 bucket
const bucket = Bucket(...);

Like TypeScript, Python supports namespaced module imports and selective imports. Namespaces in Python look like aws_cdk. xxx, where xxx represents an AWS service name, such as s3 for Amazon S3. (Amazon S3 is used in these examples).

# Import main CDK library as cdk
import aws_cdk as cdk

# Selective import of specific core classes
from aws_cdk import Stack, App

# Import entire module as s3 into current namespace
import aws_cdk.aws_s3 as s3

# s3 can now be used to access classes it contains
bucket = s3.Bucket(...)

# Selective import of s3.Bucket into current namespace
from aws_cdk.s3 import Bucket

# Bucket can now be used to instantiate a bucket
bucket = Bucket(...)

Java’s imports work differently from TypeScript’s. Each import statement imports either a single class name from a given package, or all classes defined in that package (using \*). Classes may be accessed using either the class name by itself if it has been imported, or the qualified class name including its package.

Libraries are named like software.amazon.awscdk.services.xxx for the AWS Construct Library (the main library is software.amazon.awscdk). The Maven group ID for AWS CDK packages is software.amazon.awscdk.

// Make certain core classes available
import software.amazon.awscdk.Stack;
import software.amazon.awscdk.App;

// Make all Amazon S3 construct library classes available
import software.amazon.awscdk.services.s3.*;

// Make only Bucket and EventType classes available
import software.amazon.awscdk.services.s3.Bucket;
import software.amazon.awscdk.services.s3.EventType;

// An imported class may now be accessed using the simple class name (assuming that name
// does not conflict with another class)
Bucket bucket = Bucket.Builder.create(...).build();

// We can always use the qualified name of a class (including its package) even without an
// import directive
software.amazon.awscdk.services.s3.Bucket bucket =
    software.amazon.awscdk.services.s3.Bucket.Builder.create(...)
        .build();

// Java 10 or later can use var keyword to avoid typing the type twice
var bucket =
    software.amazon.awscdk.services.s3.Bucket.Builder.create(...)
        .build();

In C#, you import types with the using directive. There are two styles. One gives you access to all the types in the specified namespace by using their plain names. With the other, you can refer to the namespace itself by using an alias.

Packages are named like Amazon.CDK.AWS.xxx for AWS Construct Library packages. (The core module is Amazon.CDK.)

// Make CDK base classes available under cdk
using cdk = Amazon.CDK;

// Make all Amazon S3 construct library classes available
using Amazon.CDK.AWS.S3;

// Now we can access any S3 type using its name
var bucket = new Bucket(...);

// Import the S3 namespace under an alias
using s3 = Amazon.CDK.AWS.S3;

// Now we can access an S3 type through the namespace alias
var bucket = new s3.Bucket(...);

// We can always use the qualified name of a type (including its namespace) even without a
// using directive
var bucket = new Amazon.CDK.AWS.S3.Bucket(...);

Each AWS Construct Library module is provided as a Go package.

import (
    "github.com/aws/aws-cdk-go/awscdk/v2"           // CDK core package
    "github.com/aws/aws-cdk-go/awscdk/v2/awss3"     // AWS S3 construct library module
)

// now instantiate a bucket
bucket := awss3.NewBucket(...)

// use aliases for brevity/clarity
import (
    cdk "github.com/aws/aws-cdk-go/awscdk/v2"           // CDK core package
    s3  "github.com/aws/aws-cdk-go/awscdk/v2/awss3"     // AWS S3 construct library module
)

bucket := s3.NewBucket(...)

// Instantiate default Bucket
const bucket = new s3.Bucket(this, 'amzn-s3-demo-bucket');

// Instantiate Bucket with bucketName and versioned properties
const bucket = new s3.Bucket(this, 'amzn-s3-demo-bucket', {
  bucketName: 'amzn-s3-demo-bucket',
   versioned: true,
});

// Instantiate Bucket with websiteRedirect, which has its own sub-properties
const bucket = new s3.Bucket(this, 'amzn-s3-demo-bucket', {
  websiteRedirect: {host: 'aws.amazon.com'}});

Python doesn’t use a new keyword when instantiating a class. The properties argument is represented using keyword arguments, and the arguments are named using snake_case.

If a props value is itself a bundle of attributes, it is represented by a class named after the property, which accepts keyword arguments for the subproperties.

In Python, the current instance is passed to methods as the first argument, which is named self by convention.

# Instantiate default Bucket
bucket = s3.Bucket(self, "amzn-s3-demo-bucket")

# Instantiate Bucket with bucket_name and versioned properties
bucket = s3.Bucket(self, "amzn-s3-demo-bucket", bucket_name="amzn-s3-demo-bucket", versioned=true)

# Instantiate Bucket with website_redirect, which has its own sub-properties
bucket = s3.Bucket(self, "amzn-s3-demo-bucket", website_redirect=s3.WebsiteRedirect(
            host_name="aws.amazon.com"))

In Java, the props argument is represented by a class named XxxxProps (for example, BucketProps for the Bucket construct’s props). You build the props argument using a builder pattern.

Each XxxxProps class has a builder. There is also a convenient builder for each construct that builds the props and the construct in one step, as shown in the following example.

Props are named the same as in TypeScript, using camelCase.

// Instantiate default Bucket
Bucket bucket = Bucket(self, "amzn-s3-demo-bucket");

// Instantiate Bucket with bucketName and versioned properties
Bucket bucket = Bucket.Builder.create(self, "amzn-s3-demo-bucket")
                      .bucketName("amzn-s3-demo-bucket").versioned(true)
                      .build();

# Instantiate Bucket with websiteRedirect, which has its own sub-properties
Bucket bucket = Bucket.Builder.create(self, "amzn-s3-demo-bucket")
                      .websiteRedirect(new websiteRedirect.Builder()
                          .hostName("aws.amazon.com").build())
                      .build();

In C#, props are specified using an object initializer to a class named XxxxProps (for example, BucketProps for the Bucket construct’s props).

Props are named similarly to TypeScript, except using PascalCase.

It is convenient to use the var keyword when instantiating a construct, so you don’t need to type the class name twice. However, your local code style guide may vary.

// Instantiate default Bucket
var bucket = Bucket(self, "amzn-s3-demo-bucket");

// Instantiate Bucket with BucketName and Versioned properties
var bucket =  Bucket(self, "amzn-s3-demo-bucket", new BucketProps {
                      BucketName = "amzn-s3-demo-bucket",
                      Versioned  = true});

// Instantiate Bucket with WebsiteRedirect, which has its own sub-properties
var bucket = Bucket(self, "amzn-s3-demo-bucket", new BucketProps {
                      WebsiteRedirect = new WebsiteRedirect {
                              HostName = "aws.amazon.com"
                      }});

To create a construct in Go, call the function NewXxxxxx where Xxxxxxx is the name of the construct. The constructs' properties are defined as a struct.

In Go, all construct parameters are pointers, including values like numbers, Booleans, and strings. Use the convenience functions like jsii.String to create these pointers.

	// Instantiate default Bucket
	bucket := awss3.NewBucket(stack, jsii.String("amzn-s3-demo-bucket"), nil)

	// Instantiate Bucket with BucketName and Versioned properties
	bucket1 := awss3.NewBucket(stack, jsii.String("amzn-s3-demo-bucket"), &awss3.BucketProps{
		BucketName: jsii.String("amzn-s3-demo-bucket"),
		Versioned:  jsii.Bool(true),
	})

	// Instantiate Bucket with WebsiteRedirect, which has its own sub-properties
	bucket2 := awss3.NewBucket(stack, jsii.String("amzn-s3-demo-bucket"), &awss3.BucketProps{
		WebsiteRedirect: &awss3.RedirectTarget{
			HostName: jsii.String("aws.amazon.com"),
		}})

Names are camelCase.

bucket.bucketArn

Names are snake_case.

bucket.bucket_arn

A getter method is provided for each property; these names are camelCase.

bucket.getBucketArn()

Names are PascalCase.

bucket.BucketArn

Names are PascalCase.

bucket.BucketArn

import { IAspect, IConstruct } from 'aws-cdk-lib';

class MyAspect implements IAspect {
  public visit(node: IConstruct) {
    console.log('Visited', node.node.path);
  }
}

Python doesn’t have an interface feature. However, for the AWS CDK you can indicate interface implementation by decorating your class with @jsii.implements(interface).

from aws_cdk import IAspect, IConstruct
import jsii

@jsii.implements(IAspect)
class MyAspect():
  def visit(self, node: IConstruct) -> None:
    print("Visited", node.node.path)

import software.amazon.awscdk.IAspect;
import software.amazon.awscdk.IConstruct;

public class MyAspect implements IAspect {
    public void visit(IConstruct node) {
        System.out.format("Visited %s", node.getNode().getPath());
    }
}

using Amazon.CDK;

public class MyAspect : IAspect
{
    public void Visit(IConstruct node)
    {
        System.Console.WriteLine($"Visited ${node.Node.Path}");
    }
}

Go structs do not need to explicitly declare which interfaces they implement. The Go compiler determines implementation based on the methods and properties available on the structure. For example, in the following code, MyAspect implements the IAspect interface because it provides a Visit method that takes a construct.

type MyAspect struct {
}

func (a MyAspect) Visit(node constructs.IConstruct) {
	fmt.Println("Visited", *node.Node().Path())
}