# CfnRule

Creates or updates the specified rule.

Rules are enabled by default, or based on value of the state. You can disable a rule using [DisableRule](https://docs.aws.amazon.com/eventbridge/latest/APIReference/API_DisableRule.html) .

A single rule watches for events from a single event bus. Events generated by AWS services go to your account's default event bus. Events generated by SaaS partner services or applications go to the matching partner event bus. If you have custom applications or services, you can specify whether their events go to your default event bus or a custom event bus that you have created. For more information, see [CreateEventBus](https://docs.aws.amazon.com/eventbridge/latest/APIReference/API_CreateEventBus.html) .

If you are updating an existing rule, the rule is replaced with what you specify in this `PutRule` command. If you omit arguments in `PutRule` , the old values for those arguments are not kept. Instead, they are replaced with null values.

When you create or update a rule, incoming events might not immediately start matching to new or updated rules. Allow a short period of time for changes to take effect.

A rule must contain at least an EventPattern or ScheduleExpression. Rules with EventPatterns are triggered when a matching event is observed. Rules with ScheduleExpressions self-trigger based on the given schedule. A rule can have both an EventPattern and a ScheduleExpression, in which case the rule triggers on matching events as well as on a schedule.

Most services in AWS treat : or / as the same character in Amazon Resource Names (ARNs). However, EventBridge uses an exact match in event patterns and rules. Be sure to use the correct ARN characters when creating event patterns so that they match the ARN syntax in the event you want to match.

In EventBridge, it is possible to create rules that lead to infinite loops, where a rule is fired repeatedly. For example, a rule might detect that ACLs have changed on an S3 bucket, and trigger software to change them to the desired state. If the rule is not written carefully, the subsequent change to the ACLs fires the rule again, creating an infinite loop.

To prevent this, write the rules so that the triggered actions do not re-fire the same rule. For example, your rule could fire only if ACLs are found to be in a bad state, instead of after any change.

An infinite loop can quickly cause higher than expected charges. We recommend that you use budgeting, which alerts you when charges exceed your specified limit. For more information, see [Managing Your Costs with Budgets](https://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/budgets-managing-costs.html) .

> As an aid to help you jumpstart developing CloudFormation templates, the EventBridge console enables you to create templates from the existing rules in your account. For more information, see [Generating CloudFormation templates from an EventBridge rule](https://docs.aws.amazon.com/eventbridge/latest/userguide/rule-generate-template.html) in the *Amazon EventBridge User Guide* .

Extends: Construct › CfnElement › CfnRefElement › CfnResource › CfnRule
Implements: IInspectable, ITaggableV2, IEnvironmentAware, IRuleRef, IConstruct, IDependable

- CloudFormation: [`AWS::Events::Rule`](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-resource-events-rule.html)
- Source: Generated code
- Type last changed: v2.268.0 · 2 Sep 2026

## Example

```ts
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 myBucket = new s3.Bucket(scope, 'Bucket');
const bucketEvents = BucketEvents.fromBucket(myBucket);
declare const fn: lambda.Function;

new events.Rule(scope, 'Rule', {
  eventPattern: bucketEvents.objectCreatedPattern({
    object: { key: events.Match.wildcard('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: events.Match.wildcard('uploads/*') },
  }),
  targets: [{ arn: fn.functionArn, id: 'L1' }]
});
```

## Initializer

```ts
new CfnRule(scope: Construct, id: string, props?: CfnRuleProps)
```

## Construct Props

- `description`: string — The description of the rule.

- `eventBusName`: string | [IEventBusRef](/cdk/api/v2/docs/aws-cdk-lib.interfaces.aws_events.IEventBusRef.html) — The name or ARN of the event bus associated with the rule.

  If you omit this, the default event bus is used.

- `eventPattern`: any — The event pattern of the rule.

  For more information, see [Events and Event Patterns](https://docs.aws.amazon.com/eventbridge/latest/userguide/eventbridge-and-event-patterns.html) in the **Amazon EventBridge User Guide** .

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

- `roleArn`: string | [IRoleRef](/cdk/api/v2/docs/aws-cdk-lib.interfaces.aws_iam.IRoleRef.html) — The Amazon Resource Name (ARN) of the role that is used for target invocation.

  If you're setting an event bus in another account as the target and that account granted permission to your account through an organization instead of directly by the account ID, you must specify a `RoleArn` with proper permissions in the `Target` structure, instead of here in this parameter.

- `scheduleExpression`: string — The scheduling expression.

  For example, "cron(0 20 * * ? *)", "rate(5 minutes)". For more information, see [Creating an Amazon EventBridge rule that runs on a schedule](https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-create-rule-schedule.html) .

- `state`: string — The state of the rule.

  Valid values include:

  - `DISABLED` : The rule is disabled. EventBridge does not match any events against the rule.
  - `ENABLED` : The rule is enabled. EventBridge matches events against the rule, *except* for AWS management events delivered through CloudTrail.
  - `ENABLED_WITH_ALL_CLOUDTRAIL_MANAGEMENT_EVENTS` : The rule is enabled for all events, including AWS management events delivered through CloudTrail.

  Management events provide visibility into management operations that are performed on resources in your AWS account. These are also known as control plane operations. For more information, see [Logging management events](https://docs.aws.amazon.com/awscloudtrail/latest/userguide/logging-management-events-with-cloudtrail.html#logging-management-events) in the *CloudTrail User Guide* , and [Filtering management events from AWS services](https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-service-event.html#eb-service-event-cloudtrail) in the **Amazon EventBridge User Guide** .

  This value is only valid for rules on the [default](https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-what-is-how-it-works-concepts.html#eb-bus-concepts-buses) event bus or [custom event buses](https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-create-event-bus.html) . It does not apply to [partner event buses](https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-saas.html) .

- `tags`: [CfnTag](/cdk/api/v2/docs/aws-cdk-lib.CfnTag.html)[] — Any tags assigned to the event rule.

- `targets`: [IResolvable](/cdk/api/v2/docs/aws-cdk-lib.IResolvable.html) | [IResolvable](/cdk/api/v2/docs/aws-cdk-lib.IResolvable.html) | [CfnRule.TargetProperty](/cdk/api/v2/docs/aws-cdk-lib.aws_events.CfnRule.TargetProperty.html)[] — Adds the specified targets to the specified rule, or updates the targets if they are already associated with the rule.

  Targets are the resources that are invoked when a rule is triggered.

  The maximum number of entries per request is 10.

  > Each rule can have up to five (5) targets associated with it at one time.

  For a list of services you can configure as targets for events, see [EventBridge targets](https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-targets.html) in the **Amazon EventBridge User Guide** .

  Creating rules with built-in targets is supported only in the AWS Management Console . The built-in targets are:

  - `Amazon EBS CreateSnapshot API call`
  - `Amazon EC2 RebootInstances API call`
  - `Amazon EC2 StopInstances API call`
  - `Amazon EC2 TerminateInstances API call`

  For some target types, `PutTargets` provides target-specific parameters. If the target is a Kinesis data stream, you can optionally specify which shard the event goes to by using the `KinesisParameters` argument. To invoke a command on multiple EC2 instances with one rule, you can use the `RunCommandParameters` field.

  To be able to make API calls against the resources that you own, Amazon EventBridge needs the appropriate permissions:

  - For AWS Lambda and Amazon SNS resources, EventBridge relies on resource-based policies.
  - For EC2 instances, Kinesis Data Streams, AWS Step Functions state machines and API Gateway APIs, EventBridge relies on IAM roles that you specify in the `RoleARN` argument in `PutTargets` .

  For more information, see [Authentication and Access Control](https://docs.aws.amazon.com/eventbridge/latest/userguide/auth-and-access-control-eventbridge.html) in the **Amazon EventBridge User Guide** .

  If another AWS account is in the same region and has granted you permission (using `PutPermission` ), you can send events to that account. Set that account's event bus as a target of the rules in your account. To send the matched events to the other account, specify that account's event bus as the `Arn` value when you run `PutTargets` . If your account sends events to another account, your account is charged for each sent event. Each event sent to another account is charged as a custom event. The account receiving the event is not charged. For more information, see [Amazon EventBridge Pricing](https://docs.aws.amazon.com/eventbridge/pricing/) .

  > `Input` , `InputPath` , and `InputTransformer` are not available with `PutTarget` if the target is an event bus of a different AWS account.

  If you are setting the event bus of another account as the target, and that account granted permission to your account through an organization instead of directly by the account ID, then you must specify a `RoleArn` with proper permissions in the `Target` structure. For more information, see [Sending and Receiving Events Between AWS Accounts](https://docs.aws.amazon.com/eventbridge/latest/userguide/eventbridge-cross-account-event-delivery.html) in the *Amazon EventBridge User Guide* .

  > If you have an IAM role on a cross-account event bus target, a `PutTargets` call without a role on the same target (same `Id` and `Arn` ) will not remove the role.

  For more information about enabling cross-account events, see [PutPermission](https://docs.aws.amazon.com/eventbridge/latest/APIReference/API_PutPermission.html) .

  *Input* , *InputPath* , and *InputTransformer* are mutually exclusive and optional parameters of a target. When a rule is triggered due to a matched event:

  - If none of the following arguments are specified for a target, then the entire event is passed to the target in JSON format (unless the target is Amazon EC2 Run Command or Amazon ECS task, in which case nothing from the event is passed to the target).
  - If *Input* is specified in the form of valid JSON, then the matched event is overridden with this constant.
  - If *InputPath* is specified in the form of JSONPath (for example, `$.detail` ), then only the part of the event specified in the path is passed to the target (for example, only the detail part of the event is passed).
  - If *InputTransformer* is specified, then one or more specified JSONPaths are extracted from the event and used as values in a template that you specify as the input to the target.

  When you specify `InputPath` or `InputTransformer` , you must use JSON dot notation, not bracket notation.

  When you add targets to a rule and the associated rule triggers soon after, new or updated targets might not be immediately invoked. Allow a short period of time for changes to take effect.

  This action can partially fail if too many requests are made at the same time. If that happens, `FailedEntryCount` is non-zero in the response and each entry in `FailedEntries` provides the ID of the failed target and the error code.

## Properties

- `attrArn`: string — The ARN of the rule, such as `arn:aws:events:us-east-2:123456789012:rule/example` .

- `attrRuleName`: string — The name of the rule, exposed as a read-only attribute for use with Fn::GetAtt.

- `cdkTagManager`: [TagManager](/cdk/api/v2/docs/aws-cdk-lib.TagManager.html) — Tag Manager which manages the tags for this resource.

- `CFN_RESOURCE_TYPE_NAME`: string (static) — The CloudFormation resource type name for this resource class.

- `cfnOptions`: [ICfnResourceOptions](/cdk/api/v2/docs/aws-cdk-lib.ICfnResourceOptions.html) — Options for this resource, such as condition, update policy etc.

- `cfnResourceType`: string — AWS resource type.

- `creationStack`: string[]

- `description`: string — The description of the rule.

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

- `eventBusName`: string — The name or ARN of the event bus associated with the rule.

- `eventPattern`: any — The event pattern of the rule.

- `logicalId`: string — The logical ID for this CloudFormation stack element.

  The logical ID of the element
  is calculated from the path of the resource node in the construct tree.

  To override this value, use `overrideLogicalId(newLogicalId)`.

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

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

- `ref`: string — Return a string that will be resolved to a CloudFormation `{ Ref }` for this element.

  If, by any chance, the intrinsic reference of a resource is not a string, you could
  coerce it to an IResolvable through `Lazy.any({ produce: resource.ref })`.

- `roleArn`: string — The Amazon Resource Name (ARN) of the role that is used for target invocation.

- `ruleRef`: [RuleReference](/cdk/api/v2/docs/aws-cdk-lib.interfaces.aws_events.RuleReference.html) — A reference to a Rule resource.

- `scheduleExpression`: string — The scheduling expression.

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

  CfnElements must be defined within a stack scope (directly or indirectly).

- `state`: string — The state of the rule.

- `tags`: [CfnTag](/cdk/api/v2/docs/aws-cdk-lib.CfnTag.html)[] — Any tags assigned to the event rule.

- `targets`: [IResolvable](/cdk/api/v2/docs/aws-cdk-lib.IResolvable.html) | [IResolvable](/cdk/api/v2/docs/aws-cdk-lib.IResolvable.html) | [CfnRule.TargetProperty](/cdk/api/v2/docs/aws-cdk-lib.aws_events.CfnRule.TargetProperty.html)[] — Adds the specified targets to the specified rule, or updates the targets if they are already associated with the rule.

## Methods

- `addDeletionOverride(path: string): void` — Syntactic sugar for `addOverride(path, undefined)`.

  **Parameters**

  - `path` — The path of the value to delete.

- `addDependency(target: CfnResource): void` — Use `addResourceDependency` instead.

  This method has been renamed to `addResourceDependency` to more clearly
  set it apart from `construct.node.addDependency`. See the documentation
  of that function for more details.

- `addDependsOn(target: CfnResource): void` — Use `addResourceDependency` instead.

  This can be used for resources across stacks (or nested stack) boundaries
  and the dependency will automatically be transferred to the relevant scope.

  This method has been renamed to `addResourceDependency`, which makes it
  more clear that this method operates at a different level from the
  construct-level `construct.node.addDependency()` mechanism.

- `addMetadata(key: string, value: any): void` — Add a value to the CloudFormation Resource Metadata.

- `addOverride(path: string, value: any): void` — Adds an override to the synthesized CloudFormation resource.

  To add a
  property override, either use `addPropertyOverride` or prefix `path` with
  "Properties." (i.e. `Properties.TopicName`).

  If the override is nested, separate each nested level using a dot (.) in the path parameter.
  If there is an array as part of the nesting, specify the index in the path.

  To include a literal `.` in the property name, prefix with a `\`. In most
  programming languages you will need to write this as `"\\."` because the
  `\` itself will need to be escaped.

  For example,
  ```typescript
  cfnResource.addOverride('Properties.GlobalSecondaryIndexes.0.Projection.NonKeyAttributes', ['myattribute']);
  cfnResource.addOverride('Properties.GlobalSecondaryIndexes.1.ProjectionType', 'INCLUDE');
  ```
  would add the overrides
  ```json
  "Properties": {
    "GlobalSecondaryIndexes": [
      {
        "Projection": {
          "NonKeyAttributes": [ "myattribute" ]
          ...
        }
        ...
      },
      {
        "ProjectionType": "INCLUDE"
        ...
      },
    ]
    ...
  }
  ```

  The `value` argument to `addOverride` will not be processed or translated
  in any way. Pass raw JSON values in here with the correct capitalization
  for CloudFormation. If you pass CDK classes or structs, they will be
  rendered with lowercased key names, and CloudFormation will reject the
  template.

  **Parameters**

  - `path` — - The path of the property, you can use dot notation to override values in complex types.
  - `value` — - The value.

- `addPropertyDeletionOverride(propertyPath: string): void` — Adds an override that deletes the value of a property from the resource definition.

  **Parameters**

  - `propertyPath` — The path to the property.

- `addPropertyOverride(propertyPath: string, value: any): void` — Adds an override to a resource property.

  Syntactic sugar for `addOverride("Properties.<...>", value)`.

  **Parameters**

  - `propertyPath` — The path of the property.
  - `value` — The value.

- `addResourceDependency(target: CfnResource, reason?: string): void` — Indicates that this resource depends on another resource and cannot be provisioned unless the other resource has been successfully provisioned.

  This can be used for resources across stacks (or nested stack) boundaries
  and the dependency will automatically be transferred to the relevant scope.

  This method only adds dependencies between L1 resources. If you are
  looking for a generic construct-to-construct dependency mechanism that works
  for all constructs including L2s, use `construct.node.addDependency` instead.

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

  When set, any cross-stack reference to this resource will use the specified
  strength instead of the global default from the consuming stack's context.

  **Parameters**

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

- `applyRemovalPolicy(policy?: RemovalPolicy, options?: RemovalPolicyOptions): void` — Sets the deletion policy of the resource based on the removal policy specified.

  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`). In some
  cases, a snapshot can be taken of the resource prior to deletion
  (`RemovalPolicy.SNAPSHOT`). A list of resources that support this policy
  can be found in the following link:

- `arnForRule(resource: IRuleRef): string` (static)

- `cfnPropertyName(cdkPropertyName: string): string`

- `fromRuleArn(scope: Construct, id: string, arn: string): IRuleRef` (static) — Creates a new IRuleRef from an ARN.

- `getAtt(attributeName: string, typeHint?: ResolutionTypeHint): Reference` — Returns a token for an runtime attribute of this resource.

  Ideally, use generated attribute accessors (e.g. `resource.arn`), but this can be used for future compatibility
  in case there is no generated attribute.

  **Parameters**

  - `attributeName` — The name of the attribute.

- `getMetadata(key: string): any` — Retrieve a value value from the CloudFormation Resource Metadata.

- `inspect(inspector: TreeInspector): void` — Examines the CloudFormation resource and discloses attributes.

  **Parameters**

  - `inspector` — tree inspector to collect and process attributes.

- `isCfnElement(x: any): boolean` (static) — Returns `true` if a construct is a stack element (i.e. part of the synthesized cloudformation template).

  Uses duck-typing instead of `instanceof` to allow stack elements from different
  versions of this library to be included in the same stack.

  **Returns:** The construct as a stack element or undefined if it is not a stack element.

- `isCfnResource(x: any): boolean` (static) — Check whether the given object is a CfnResource.

- `isCfnRule(x: any): boolean` (static) — Checks whether the given object is a CfnRule.

- `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`.

- `obtainDependencies(): Stack | CfnResource[]` — Retrieves an array of resources and stacks this resource depends on.

  For resources depended on directly, returns the `CfnResource` object. For
  dependencies on other stacks, returns the `Stack` object. The order of the
  array is not guaranteed.

- `overrideLogicalId(newLogicalId: string): void` — Overrides the auto-generated logical ID with a specific ID.

  **Parameters**

  - `newLogicalId` — The new logical ID to use for this stack element.

- `removeDependency(target: CfnResource): void` — Use `removeResourceDependency` instead

  This can be used for resources across stacks (including nested stacks)
  and the dependency will automatically be removed from the relevant scope.

- `removeResourceDependency(target: CfnResource): void` — Indicates that this resource no longer depends on another resource.

  This can be used for resources across stacks (including nested stacks)
  and the dependency will automatically be removed from the relevant scope.

- `replaceDependency(target: CfnResource, newTarget: CfnResource): void` — Replaces one dependency with another.

  **Parameters**

  - `target` — The dependency to replace.
  - `newTarget` — The new dependency to add.

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

  **Returns:** a string representation of this resource

- `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.