# CustomRule

A new custom rule.

Extends: Construct › Resource › CustomRule
Implements: IResource, IRule, IEnvironmentAware, IConfigRuleRef, IConstruct, IDependable

- CloudFormation: [`AWS::Config::ConfigRule`](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-resource-config-configrule.html)
- L1 type: [`CfnConfigRule`](/cdk/api/v2/docs/aws-cdk-lib.aws_config.CfnConfigRule.html)
- Source: [`aws-config/lib/rule.ts`](https://github.com/aws/aws-cdk/blob/v2.275.0/packages/aws-cdk-lib/aws-config/lib/rule.ts#L435)
- Type last changed: v2.236.0 · 23 Jan 2026

## Example

```ts
declare const fn: lambda.Function;
declare const samplePolicyText: string;

new config.ManagedRule(this, 'ManagedRule', {
  identifier: config.ManagedRuleIdentifiers.API_GW_XRAY_ENABLED,
  evaluationModes: config.EvaluationMode.DETECTIVE_AND_PROACTIVE,
});

new config.CustomRule(this, 'CustomRule', {
  lambdaFunction: fn,
  evaluationModes: config.EvaluationMode.PROACTIVE,
});

new config.CustomPolicy(this, 'CustomPolicy', {
  policyText: samplePolicyText,
  evaluationModes: config.EvaluationMode.DETECTIVE,
});
```

## Initializer

```ts
new CustomRule(scope: Construct, id: string, props: CustomRuleProps)
```

## Construct Props

- `configRuleName`: string — A name for the AWS Config rule.

  **Default:** CloudFormation generated name

- `configurationChanges`: boolean = false — Whether to run the rule on configuration changes.

- `description`: string — A description about this AWS Config rule.

  **Default:** No description

- `evaluationModes`: [EvaluationMode](/cdk/api/v2/docs/aws-cdk-lib.aws_config.EvaluationMode.html) — The modes the AWS Config rule can be evaluated in.

  **Default:** Detective evaluation mode only

  The valid values are distinct objects.

- `inputParameters`: { [key: string]: any } — Input parameter values that are passed to the AWS Config rule.

  **Default:** No input parameters

- `lambdaFunction`: [IFunction](/cdk/api/v2/docs/aws-cdk-lib.aws_lambda.IFunction.html) (required) — The Lambda function to run.

- `maximumExecutionFrequency`: [MaximumExecutionFrequency](/cdk/api/v2/docs/aws-cdk-lib.aws_config.MaximumExecutionFrequency.html) — The maximum frequency at which the AWS Config rule runs evaluations.

  **Default:** MaximumExecutionFrequency.TWENTY_FOUR_HOURS

- `periodic`: boolean = false — Whether to run the rule on a fixed frequency.

- `ruleScope`: [RuleScope](/cdk/api/v2/docs/aws-cdk-lib.aws_config.RuleScope.html) — Defines which resources trigger an evaluation for an AWS Config rule.

  **Default:** evaluations for the rule are triggered when any resource in the recording group changes.

## Properties

- `configRuleArn`: string — The arn of the rule.

- `configRuleComplianceType`: string — The compliance status of the rule.

- `configRuleId`: string — The id of the rule.

- `configRuleName`: string — The name of the rule.

- `configRuleRef`: [ConfigRuleReference](/cdk/api/v2/docs/aws-cdk-lib.interfaces.aws_config.ConfigRuleReference.html) — A reference to a ConfigRule resource.

- `env`: [ResourceEnvironment](/cdk/api/v2/docs/aws-cdk-lib.interfaces.ResourceEnvironment.html) — 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.

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

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

- `stack`: [Stack](/cdk/api/v2/docs/aws-cdk-lib.Stack.html) — 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`).

- `fromConfigRuleName(scope: Construct, id: string, configRuleName: string): IRule` (static) — Imports an existing rule.

  **Parameters**

  - `configRuleName` — the name of the rule.

- `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.

- `onComplianceChange(id: string, options?: OnEventOptions): Rule` — Defines an EventBridge event rule which triggers for rule compliance events.

- `onEvent(id: string, options?: OnEventOptions): Rule` — Defines an EventBridge event rule which triggers for rule events.

  Use
  `rule.addEventPattern(pattern)` to specify a filter.

- `onReEvaluationStatus(id: string, options?: OnEventOptions): Rule` — Defines an EventBridge event rule which triggers for rule re-evaluation status events.

- `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.