AWS::Events::Rule - AWS CloudFormation

AWS::Events::Rule

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.

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.

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.

Syntax

To declare this entity in your AWS CloudFormation template, use the following syntax:

JSON

{ "Type" : "AWS::Events::Rule", "Properties" : { "Description" : String, "EventBusName" : String, "EventPattern" : Json, "Name" : String, "RoleArn" : String, "ScheduleExpression" : String, "State" : String, "Targets" : [ Target, ... ] } }

YAML

Type: AWS::Events::Rule Properties: Description: String EventBusName: String EventPattern: Json Name: String RoleArn: String ScheduleExpression: String State: String Targets: - Target

Properties

Description

The description of the rule.

Required: No

Type: String

Maximum: 512

Update requires: No interruption

EventBusName

The name or ARN of the event bus associated with the rule. If you omit this, the default event bus is used.

Required: No

Type: String

Minimum: 1

Maximum: 256

Pattern: [/\.\-_A-Za-z0-9]+

Update requires: Replacement

EventPattern

The event pattern of the rule. For more information, see Events and Event Patterns in the Amazon EventBridge User Guide.

Required: Conditional

Type: Json

Update requires: No interruption

Name

The name of the rule.

Required: No

Type: String

Minimum: 1

Maximum: 64

Pattern: [\.\-_A-Za-z0-9]+

Update requires: Replacement

RoleArn

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.

Required: No

Type: String

Minimum: 1

Maximum: 1600

Update requires: No interruption

ScheduleExpression

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.

Required: Conditional

Type: String

Maximum: 256

Update requires: No interruption

State

The state of the rule.

Required: No

Type: String

Allowed values: DISABLED | ENABLED

Update requires: No interruption

Targets

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.

You can configure the following as targets for Events:

  • API destination

  • Amazon API Gateway REST API endpoints

  • API Gateway

  • AWS Batch job queue

  • CloudWatch Logs group

  • CodeBuild project

  • CodePipeline

  • Amazon EC2 CreateSnapshot API call

  • EC2 Image Builder

  • Amazon EC2 RebootInstances API call

  • Amazon EC2 StopInstances API call

  • Amazon EC2 TerminateInstances API call

  • Amazon ECS tasks

  • Event bus in a different AWS account or Region.

    You can use an event bus in the US East (N. Virginia) us-east-1, US West (Oregon) us-west-2, or Europe (Ireland) eu-west-1 Regions as a target for a rule.

  • Firehose delivery stream (Kinesis Data Firehose)

  • Inspector assessment template (Amazon Inspector)

  • Kinesis stream (Kinesis Data Stream)

  • AWS Lambda function

  • Redshift clusters (Data API statement execution)

  • Amazon SNS topic

  • Amazon SQS queues (includes FIFO queues)

  • SSM Automation

  • SSM OpsItem

  • SSM Run Command

  • Step Functions state machines

Creating rules with built-in targets is supported only in the AWS Management Console. The built-in targets are EC2 CreateSnapshot API call, EC2 RebootInstances API call, EC2 StopInstances API call, and 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 REST APIs, EventBridge relies on IAM roles that you specify in the RoleARN argument in PutTargets. For more information, see Authentication and Access Control 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.

Note

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 in the Amazon EventBridge User Guide.

For more information about enabling cross-account events, see PutPermission.

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.

Required: No

Type: List of Target

Update requires: No interruption

Return values

Ref

When you pass the logical ID of this resource to the intrinsic Ref function, Ref returns event rule ID, such as mystack-ScheduledRule-ABCDEFGHIJK.

For more information about using the Ref function, see Ref.

Fn::GetAtt

Arn

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

Examples

Create a rule that includes a dead-letter queue for a target

The following example demonstrates how to send all EC2 events to an SQS queue, and include a dead-letter queue and retry policy settings for the target of the rule.

JSON

{ "MyNewEventsRule": { "Type": "AWS::Events::Rule", "Properties": { "Description": "Test Events Rule", "Name": "mynewabc", "EventPattern": { "source": [ "aws.ec2" ] }, "State": "ENABLED", "Targets": [ { "Arn": "arn:aws:sqs:us-west-2:081035103721:demoSQS", "Id": "Id1234", "RetryPolicy": { "MaximumRetryAttempts": 4, "MaximumEventAgeInSeconds": 400 }, "DeadLetterConfig": { "Arn": "arn:aws:sqs:us-west-2:081035103721:demoDLQ" } } ] } } }

YAML

MyNewEventsRule: Type: 'AWS::Events::Rule' Properties: Description: Test Events Rule Name: mynewabc EventPattern: source: - aws.ec2 State: ENABLED Targets: - Arn: 'arn:aws:sqs:us-west-2:081035103721:demoSQS' Id: Id1234 RetryPolicy: MaximumRetryAttempts: 4 MaximumEventAgeInSeconds: 400 DeadLetterConfig: Arn: 'arn:aws:sqs:us-west-2:081035103721:demoDLQ'

Regularly invoke Lambda function

The following example creates a rule that invokes the specified Lambda function every 10 minutes. The PermissionForEventsToInvokeLambda resource grants EventBridge permission to invoke the associated function.

JSON

"ScheduledRule": { "Type": "AWS::Events::Rule", "Properties": { "Description": "ScheduledRule", "ScheduleExpression": "rate(10 minutes)", "State": "ENABLED", "Targets": [{ "Arn": { "Fn::GetAtt": ["LambdaFunction", "Arn"] }, "Id": "TargetFunctionV1" }] } }, "PermissionForEventsToInvokeLambda": { "Type": "AWS::Lambda::Permission", "Properties": { "FunctionName": { "Ref": "LambdaFunction" }, "Action": "lambda:InvokeFunction", "Principal": "events.amazonaws.com", "SourceArn": { "Fn::GetAtt": ["ScheduledRule", "Arn"] } } }

YAML

ScheduledRule: Type: AWS::Events::Rule Properties: Description: "ScheduledRule" ScheduleExpression: "rate(10 minutes)" State: "ENABLED" Targets: - Arn: Fn::GetAtt: - "LambdaFunction" - "Arn" Id: "TargetFunctionV1" PermissionForEventsToInvokeLambda: Type: AWS::Lambda::Permission Properties: FunctionName: !Ref "LambdaFunction" Action: "lambda:InvokeFunction" Principal: "events.amazonaws.com" SourceArn: Fn::GetAtt: - "ScheduledRule" - "Arn"

Invoke Lambda Function in Response to an Event

The following example creates a rule that invokes the specified Lambda function when any EC2 instance's state changes to stopping.

JSON

"EventRule": { "Type": "AWS::Events::Rule", "Properties": { "Description": "EventRule", "EventPattern": { "source": [ "aws.ec2" ], "detail-type": [ "EC2 Instance State-change Notification" ], "detail": { "state": [ "stopping" ] } }, "State": "ENABLED", "Targets": [{ "Arn": { "Fn::GetAtt": ["LambdaFunction", "Arn"] }, "Id": "TargetFunctionV1" }] } }, "PermissionForEventsToInvokeLambda": { "Type": "AWS::Lambda::Permission", "Properties": { "FunctionName": { "Ref": "LambdaFunction" }, "Action": "lambda:InvokeFunction", "Principal": "events.amazonaws.com", "SourceArn": { "Fn::GetAtt": ["EventRule", "Arn"] } } }

YAML

EventRule: Type: AWS::Events::Rule Properties: Description: "EventRule" EventPattern: source: - "aws.ec2" detail-type: - "EC2 Instance State-change Notification" detail: state: - "stopping" State: "ENABLED" Targets: - Arn: Fn::GetAtt: - "LambdaFunction" - "Arn" Id: "TargetFunctionV1" PermissionForEventsToInvokeLambda: Type: AWS::Lambda::Permission Properties: FunctionName: Ref: "LambdaFunction" Action: "lambda:InvokeFunction" Principal: "events.amazonaws.com" SourceArn: Fn::GetAtt: - "EventRule" - "Arn"

Notify a Topic in Response to a Log Entry

The following example creates a rule that notifies an Amazon Simple Notification Service topic if an AWS CloudTrail log entry contains a call by the Root user. The EventTopicPolicy resource grants Amazon EventBridge permission to notify the associated Amazon SNS topic.

JSON

"OpsEventRule": { "Type": "AWS::Events::Rule", "Properties": { "Description": "EventRule", "EventPattern": { "detail-type": [ "AWS API Call via CloudTrail" ], "detail": { "userIdentity": { "type": [ "Root" ] } } }, "State": "ENABLED", "Targets": [ { "Arn": { "Ref": "MySNSTopic" }, "Id": "OpsTopic" } ] } } "EventTopicPolicy": { "Type": "AWS::SNS::TopicPolicy", "Properties": { "PolicyDocument": { "Statement": [ { "Effect": "Allow", "Principal": { "Service": "events.amazonaws.com" }, "Action": "sns:Publish", "Resource": "*" } ] }, "Topics": [ { "Ref": "MySNSTopic" } ] } }

YAML

OpsEventRule: Type: AWS::Events::Rule Properties: Description: "EventRule" EventPattern: detail-type: - "AWS API Call via CloudTrail" detail: userIdentity: type: - "Root" State: "ENABLED" Targets: - Arn: Ref: "MySNSTopic" Id: "OpsTopic" EventTopicPolicy: Type: 'AWS::SNS::TopicPolicy' Properties: PolicyDocument: Statement: - Effect: Allow Principal: Service: events.amazonaws.com Action: 'sns:Publish' Resource: '*' Topics: - !Ref MySNSTopic