Language	Package
.NET	`Amazon.CDK.Mixins.Preview`
Go	`github.com/aws/aws-cdk-go/awscdkmixinspreview/v2`
Java	`software.amazon.awscdk.mixins.preview`
Python	`aws_cdk.mixins_preview`
TypeScript	`@aws-cdk/mixins-preview`

CDK Mixins (Preview)

cdk-constructs: Experimental

The APIs of higher level constructs in this module are experimental and under active development. They are subject to non-backward compatible changes or removal in any future version. These are not subject to the Semantic Versioning model and breaking changes will be announced in the release notes. This means that while you may use them, you may need to update your source code when upgrading to a newer version of this package.

This package provides two main features:

Mixins - Composable abstractions for adding functionality to constructs
EventBridge Event Patterns - Type-safe event patterns for AWS resources

CDK Mixins

CDK Mixins provide a new, advanced way to add functionality through composable abstractions. Unlike traditional L2 constructs that bundle all features together, Mixins allow you to pick and choose exactly the capabilities you need for constructs.

Key Benefits

Universal Compatibility: Apply the same abstractions to L1 constructs, L2 constructs, or custom constructs
Composable Design: Mix and match features without being locked into specific implementations
Cross-Service Abstractions: Use common patterns like encryption across different AWS services
Escape Hatch Freedom: Customize resources in a safe, typed way while keeping the abstractions you want

Basic Usage

Mixins use Mixins.of() as the fundamental API for applying abstractions to constructs:

// Base form: apply mixins to any construct
const bucket = new s3.CfnBucket(scope, "MyBucket");
Mixins.of(bucket)
  .apply(new EncryptionAtRest())
  .apply(new AutoDeleteObjects());

Example not in your language?

Fluent Syntax with `.with()`

For convenience, you can use the .with() method for a more fluent syntax:

import '@aws-cdk/mixins-preview/with';

const bucket = new s3.CfnBucket(scope, "MyBucket")
  .with(new EnableVersioning())
  .with(new AutoDeleteObjects());

Example not in your language?

The .with() method is available after importing @aws-cdk/mixins-preview/with, which augments all constructs with this method. It provides the same functionality as Mixins.of().apply() but with a more chainable API.

Note: The .with() fluent syntax is only available in JavaScript and TypeScript. Other jsii languages (Python, Java, C#, and Go) should use the Mixins.of(...).mustApply() syntax instead. The import requirement is temporary during the preview phase. Once the API is stable, the .with() method will be available by default on all constructs and in all languages.

Creating Custom Mixins

Mixins are simple classes that implement the IMixin interface (usually by extending the abstract Mixin class:

// Simple mixin that enables versioning
class CustomVersioningMixin extends Mixin implements IMixin {
  supports(construct: any): boolean {
    return construct instanceof s3.CfnBucket;
  }

  applyTo(bucket: any): any {
    bucket.versioningConfiguration = {
      status: "Enabled"
    };
    return bucket;
  }
}

// Usage
const bucket = new s3.CfnBucket(scope, "MyBucket");
Mixins.of(bucket).apply(new CustomVersioningMixin());

Example not in your language?

Construct Selection

Mixins operate on construct trees and can be applied selectively:

// Apply to all constructs in a scope
Mixins.of(scope).apply(new EncryptionAtRest());

// Apply to specific resource types
Mixins.of(scope, ConstructSelector.resourcesOfType(s3.CfnBucket.CFN_RESOURCE_TYPE_NAME))
  .apply(new EncryptionAtRest());

// Apply to constructs matching a path pattern
Mixins.of(scope, ConstructSelector.byPath("**/*-prod-*/**"))
  .apply(new ProductionSecurityMixin());

Example not in your language?

Built-in Mixins

Cross-Service Mixins

EncryptionAtRest: Applies encryption to supported AWS resources

// Works across different resource types
const bucket = new s3.CfnBucket(scope, "Bucket");
Mixins.of(bucket).apply(new EncryptionAtRest());

const logGroup = new logs.CfnLogGroup(scope, "LogGroup");
Mixins.of(logGroup).apply(new EncryptionAtRest());

Example not in your language?

S3-Specific Mixins

AutoDeleteObjects: Configures automatic object deletion for S3 buckets

const bucket = new s3.CfnBucket(scope, "Bucket");
Mixins.of(bucket).apply(new AutoDeleteObjects());

Example not in your language?

EnableVersioning: Enables versioning on S3 buckets

const bucket = new s3.CfnBucket(scope, "Bucket");
Mixins.of(bucket).apply(new EnableVersioning());

Example not in your language?

Logs Delivery

Configures vended logs delivery for supported resources to various destinations:

import '@aws-cdk/mixins-preview/with';
import * as cloudfrontMixins from '@aws-cdk/mixins-preview/aws-cloudfront/mixins';

// Create CloudFront distribution
declare const bucket: s3.Bucket;
const distribution = new cloudfront.Distribution(scope, 'Distribution', {
  defaultBehavior: {
    origin: origins.S3BucketOrigin.withOriginAccessControl(bucket),
  },
});

// Create log destination
const logGroup = new logs.LogGroup(scope, 'DeliveryLogGroup');

// Configure log delivery using the mixin
distribution
  .with(cloudfrontMixins.CfnDistributionLogsMixin.CONNECTION_LOGS.toLogGroup(logGroup));

Example not in your language?

L1 Property Mixins

For every CloudFormation resource, CDK Mixins automatically generates type-safe property mixins. These allow you to apply L1 properties with full TypeScript support:

import '@aws-cdk/mixins-preview/with';

const bucket = new s3.Bucket(scope, "Bucket")
  .with(new CfnBucketPropsMixin({
    versioningConfiguration: { status: "Enabled" },
    publicAccessBlockConfiguration: {
      blockPublicAcls: true,
      blockPublicPolicy: true
    }
  }));

Example not in your language?

Property mixins support two merge strategies:

declare const bucket: s3.CfnBucket;

// MERGE (default): Deep merges properties with existing values
Mixins.of(bucket).apply(new CfnBucketPropsMixin(
  { versioningConfiguration: { status: "Enabled" } },
  { strategy: PropertyMergeStrategy.MERGE }
));

// OVERRIDE: Replaces existing property values
Mixins.of(bucket).apply(new CfnBucketPropsMixin(
  { versioningConfiguration: { status: "Enabled" } },
  { strategy: PropertyMergeStrategy.OVERRIDE }
));

Example not in your language?

Property mixins are available for all AWS services:

import { CfnLogGroupPropsMixin } from '@aws-cdk/mixins-preview/aws-logs/mixins';
import { CfnFunctionPropsMixin } from '@aws-cdk/mixins-preview/aws-lambda/mixins';
import { CfnTablePropsMixin } from '@aws-cdk/mixins-preview/aws-dynamodb/mixins';

Example not in your language?

Error Handling

Mixins provide comprehensive error handling:

// Graceful handling of unsupported constructs
Mixins.of(scope)
  .apply(new EncryptionAtRest()); // Skips unsupported constructs

// Strict application that requires all constructs to match
Mixins.of(scope)
  .mustApply(new EncryptionAtRest()); // Throws if no constructs support the mixin

Example not in your language?

EventBridge Event Patterns

CDK Mixins automatically generates typed EventBridge event patterns for AWS resources. These patterns work with both L1 and L2 constructs, providing a consistent interface for creating EventBridge rules.

Event Patterns Basic Usage

import { BucketEvents } from '@aws-cdk/mixins-preview/aws-s3/events';
import * as events from 'aws-cdk-lib/aws-events';
import * as targets from 'aws-cdk-lib/aws-events-targets';

// Works with L2 constructs
const bucket = new s3.Bucket(scope, 'Bucket');
const bucketEvents = BucketEvents.fromBucket(bucket);
declare const fn: lambda.Function;

new events.Rule(scope, 'Rule', {
  eventPattern: bucketEvents.objectCreatedPattern({
    object: { key: ['uploads/*'] }
  }),
  targets: [new targets.LambdaFunction(fn)]
});

// Also works with L1 constructs
const cfnBucket = new s3.CfnBucket(scope, 'CfnBucket');
const cfnBucketEvents = BucketEvents.fromBucket(cfnBucket);

new events.CfnRule(scope, 'CfnRule', {
  state: 'ENABLED',
  eventPattern: cfnBucketEvents.objectCreatedPattern({
    object: { key: ['uploads/*'] }
  }),
  targets: [{ arn: fn.functionArn, id: 'L1' }]
});

Example not in your language?

Event Pattern Features

Automatic Resource Injection: Resource identifiers are automatically included in patterns

import { BucketEvents } from '@aws-cdk/mixins-preview/aws-s3/events';

declare const bucket: s3.Bucket;
const bucketEvents = BucketEvents.fromBucket(bucket);

// Bucket name is automatically injected from the bucket reference
const pattern = bucketEvents.objectCreatedPattern();
// pattern.detail.bucket.name === bucket.bucketName

Example not in your language?

Event Metadata Support: Control EventBridge pattern metadata

import { BucketEvents } from '@aws-cdk/mixins-preview/aws-s3/events';

declare const bucket: s3.Bucket;
const bucketEvents = BucketEvents.fromBucket(bucket);

const pattern = bucketEvents.objectCreatedPattern({
  eventMetadata: {
    region: ['us-east-1', 'us-west-2'],
    version: ['0']
  }
});

Example not in your language?

Available Events

Event patterns are generated for EventBridge events available in the AWS Event Schema Registry. Common examples:

S3 Events:

objectCreatedPattern() - Object creation events
objectDeletedPattern() - Object deletion events
objectTagsAddedPattern() - Object tagging events
awsAPICallViaCloudTrailPattern() - CloudTrail API calls

Import events from service-specific modules:

import { BucketEvents } from '@aws-cdk/mixins-preview/aws-s3/events';

Example not in your language?

AWS CDK

2.233.0

@aws-cdk/mixins-preview module

CDK Mixins (Preview)

CDK Mixins

Key Benefits

Basic Usage

Fluent Syntax with `.with()`

Creating Custom Mixins

Construct Selection

Built-in Mixins

Cross-Service Mixins

S3-Specific Mixins

Logs Delivery

L1 Property Mixins

Error Handling

EventBridge Event Patterns

Event Patterns Basic Usage

Event Pattern Features

Available Events

CDK Mixins (Preview)

CDK Mixins

Key Benefits

Basic Usage

Fluent Syntax with .with()

Creating Custom Mixins

Construct Selection

Built-in Mixins

Cross-Service Mixins

S3-Specific Mixins

Logs Delivery

L1 Property Mixins

Error Handling

EventBridge Event Patterns

Event Patterns Basic Usage

Event Pattern Features

Available Events

Fluent Syntax with `.with()`