# Function

A CloudFront Function.

Extends: Construct › Resource › Function
Implements: IResource, IFunction, IEnvironmentAware, IFunctionRef, IConstruct, IDependable

- CloudFormation: [`AWS::CloudFront::Function`](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-resource-cloudfront-function.html)
- L1 type: [`CfnFunction`](/cdk/api/v2/docs/aws-cdk-lib.aws_cloudfront.CfnFunction.html)
- Source: [`aws-cloudfront/lib/function.ts`](https://github.com/aws/aws-cdk/blob/v2.274.0/packages/aws-cdk-lib/aws-cloudfront/lib/function.ts#L165)
- Type last changed: v2.224.0 · 13 Nov 2025

## Example

```ts
const store = new cloudfront.KeyValueStore(this, 'KeyValueStore');
new cloudfront.Function(this, 'Function', {
  code: cloudfront.FunctionCode.fromInline('function handler(event) { return event.request }'),
  // Note that JS_2_0 must be used for Key Value Store support
  runtime: cloudfront.FunctionRuntime.JS_2_0,
  keyValueStore: store,
});
```

## Initializer

```ts
new Function(scope: Construct, id: string, props: FunctionProps)
```

## Construct Props

- `autoPublish`: boolean = true — A flag that determines whether to automatically publish the function to the LIVE stage when it’s created.

- `code`: [FunctionCode](/cdk/api/v2/docs/aws-cdk-lib.aws_cloudfront.FunctionCode.html) (required) — The source code of the function.

- `comment`: string = same as `functionName` — A comment to describe the function.

- `functionName`: string = generated from the `id` — A name to identify the function.

- `keyValueStore`: [IKeyValueStoreRef](/cdk/api/v2/docs/aws-cdk-lib.interfaces.aws_cloudfront.IKeyValueStoreRef.html) = no key value store is associated — The Key Value Store to associate with this function.

  In order to associate a Key Value Store, the `runtime` must be
  `cloudfront-js-2.0` or newer.

- `runtime`: [FunctionRuntime](/cdk/api/v2/docs/aws-cdk-lib.aws_cloudfront.FunctionRuntime.html) = FunctionRuntime.JS_1_0 (unless `keyValueStore` is specified, then `FunctionRuntime.JS_2_0`) — The runtime environment for the function.

  **Default:** FunctionRuntime.JS_1_0 (unless `keyValueStore` is specified, then `FunctionRuntime.JS_2_0`)

## Properties

- `env`: [ResourceEnvironment](/cdk/api/v2/docs/aws-cdk-lib.interfaces.ResourceEnvironment.html) (required) — The environment this resource belongs to.

  For resources that are created and managed in a Stack (those created by
  creating new class instances like `new Role()`, `new Bucket()`, etc.), this
  is always the same as the environment of the stack they belong to.

  For referenced resources (those obtained from referencing methods like
  `Role.fromRoleArn()`, `Bucket.fromBucketName()`, etc.), they might be
  different than the stack they were imported into.

- `functionArn`: string (required) — the ARN of the CloudFront function.

- `functionName`: string (required) — the name of the CloudFront function.

- `functionRef`: [FunctionReference](/cdk/api/v2/docs/aws-cdk-lib.interfaces.aws_cloudfront.FunctionReference.html) (required) — A reference to a Function resource.

- `functionRuntime`: string (required) — the runtime of the CloudFront function.

- `functionStage`: string (required) — the deployment stage of the CloudFront function.

- `node`: [Node](/cdk/api/v2/docs/constructs.Node.html) (required) — The tree node.

- `PROPERTY_INJECTION_ID`: string (required) (static) — Uniquely identifies this class.

- `stack`: [Stack](/cdk/api/v2/docs/aws-cdk-lib.Stack.html) (required) — The stack in which this resource is defined.

## Methods

- `applyCrossStackReferenceStrength(strength: ReferenceStrength): void` — Override the cross-stack reference strength for this resource.

  When set, any cross-stack reference to this resource will use the specified
  mechanism instead of the global default determined by the
  `@aws-cdk/core:defaultCrossStackReferences` context key. This is useful for
  selectively weakening specific references to avoid the "deadly embrace" problem
  without changing the app-wide default.

  **Parameters**

  - `strength` — - The reference strength to use for this resource.

- `applyRemovalPolicy(policy: RemovalPolicy): void` — Apply the given removal policy to this resource.

  The Removal Policy controls what happens to this resource when it stops
  being managed by CloudFormation, either because you've removed it from the
  CDK application or because you've made a change that requires the resource
  to be replaced.

  The resource can be deleted (`RemovalPolicy.DESTROY`), or left in your AWS
  account for data recovery and cleanup later (`RemovalPolicy.RETAIN`).

- `fromFunctionAttributes(scope: Construct, id: string, attrs: FunctionAttributes): IFunction` (static) — Imports a function by its name and ARN.

- `isConstruct(x: any): boolean` (static) — Checks if `x` is a construct.

  Use this method instead of `instanceof` to properly detect `Construct`
  instances, even when the construct library is symlinked.

  Explanation: in JavaScript, multiple copies of the `constructs` library on
  disk are seen as independent, completely different libraries. As a
  consequence, the class `Construct` in each copy of the `constructs` library
  is seen as a different class, and an instance of one class will not test as
  `instanceof` the other class. `npm install` will not create installations
  like this, but users may manually symlink construct libraries together or
  use a monorepo tool: in those cases, multiple copies of the `constructs`
  library can be accidentally installed, and `instanceof` will behave
  unpredictably. It is safest to avoid using `instanceof`, and using
  this type-testing method instead.

  **Parameters**

  - `x` — Any object.

  **Returns:** true if `x` is an object created from a class which extends `Construct`.

- `isOwnedResource(construct: IConstruct): boolean` (static) — Returns true if the construct was created by CDK, and false otherwise.

- `isResource(construct: IConstruct): boolean` (static) — Check whether the given construct is a Resource.

- `toString(): string` — Returns a string representation of this construct.

- `with(...mixins: IMixin[]): IConstruct` — Applies one or more mixins to this construct.

  Mixins are applied in order. The list of constructs is captured at the
  start of the call, so constructs added by a mixin will not be visited.
  Use multiple `with()` calls if subsequent mixins should apply to added
  constructs.