2.168.0

interface EventPattern

LanguageType name
.NETAmazon.CDK.AWS.Events.EventPattern
Gogithub.com/aws/aws-cdk-go/awscdk/v2/awsevents#EventPattern
Javasoftware.amazon.awscdk.services.events.EventPattern
Pythonaws_cdk.aws_events.EventPattern
TypeScript (source)aws-cdk-lib » aws_events » EventPattern

Events in Amazon CloudWatch Events are represented as JSON objects. For more information about JSON objects, see RFC 7159.

Important: this class can only be used with a Rule class. In particular, do not use it with CfnRule class: your pattern will not be rendered correctly. In a CfnRule class, write the pattern as you normally would when directly writing CloudFormation.

Rules use event patterns to select events and route them to targets. A pattern either matches an event or it doesn't. Event patterns are represented as JSON objects with a structure that is similar to that of events.

It is important to remember the following about event pattern matching:

  • For a pattern to match an event, the event must contain all the field names listed in the pattern. The field names must appear in the event with the same nesting structure.

  • Other fields of the event not mentioned in the pattern are ignored; effectively, there is a "*": "*" wildcard for fields not mentioned.

  • The matching is exact (character-by-character), without case-folding or any other string normalization.

  • The values being matched follow JSON rules: Strings enclosed in quotes, numbers, and the unquoted keywords true, false, and null.

  • Number matching is at the string representation level. For example, 300, 300.0, and 3.0e2 are not considered equal.

For custom events, some optional properties are required. For more information, see Minimum information needed for a valid custom event.

See also: https://docs.aws.amazon.com/AmazonCloudWatch/latest/events/CloudWatchEventsandEventPatterns.html

Example

import * as lambda from 'aws-cdk-lib/aws-lambda';

const fn = new lambda.Function(this, 'MyFunc', {
  runtime: lambda.Runtime.NODEJS_LATEST,
  handler: 'index.handler',
  code: lambda.Code.fromInline(`exports.handler = handler.toString()`),
});

const rule = new events.Rule(this, 'rule', {
  eventPattern: {
    source: ["aws.ec2"],
  },
});

const queue = new sqs.Queue(this, 'Queue');

rule.addTarget(new targets.LambdaFunction(fn, {
  deadLetterQueue: queue, // Optional: add a dead letter queue
  maxEventAge: Duration.hours(2), // Optional: set the maxEventAge retry policy
  retryAttempts: 2, // Optional: set the max number of retry attempts
}));

Properties

NameTypeDescription
account?string[]The 12-digit number identifying an AWS account.
detail?{ [string]: any }A JSON object, whose content is at the discretion of the service originating the event.
detailType?string[]Identifies, in combination with the source field, the fields and values that appear in the detail field.
id?string[]A unique value is generated for every event.
region?string[]Identifies the AWS region where the event originated.
resources?string[]This JSON array contains ARNs that identify resources that are involved in the event.
source?string[]Identifies the service that sourced the event.
time?string[]The event timestamp, which can be specified by the service originating the event.
version?string[]By default, this is set to 0 (zero) in all events.

account?

Type: string[] (optional, default: No filtering on account)

The 12-digit number identifying an AWS account.

detail?

Type: { [string]: any } (optional, default: No filtering on detail)

A JSON object, whose content is at the discretion of the service originating the event.

detailType?

Type: string[] (optional, default: No filtering on detail type)

Identifies, in combination with the source field, the fields and values that appear in the detail field.

Represents the "detail-type" event field.

id?

Type: string[] (optional, default: No filtering on id)

A unique value is generated for every event.

This can be helpful in tracing events as they move through rules to targets, and are processed.

region?

Type: string[] (optional, default: No filtering on region)

Identifies the AWS region where the event originated.

resources?

Type: string[] (optional, default: No filtering on resource)

This JSON array contains ARNs that identify resources that are involved in the event.

Inclusion of these ARNs is at the discretion of the service.

For example, Amazon EC2 instance state-changes include Amazon EC2 instance ARNs, Auto Scaling events include ARNs for both instances and Auto Scaling groups, but API calls with AWS CloudTrail do not include resource ARNs.

source?

Type: string[] (optional, default: No filtering on source)

Identifies the service that sourced the event.

All events sourced from within AWS begin with "aws." Customer-generated events can have any value here, as long as it doesn't begin with "aws." We recommend the use of Java package-name style reverse domain-name strings.

To find the correct value for source for an AWS service, see the table in AWS Service Namespaces. For example, the source value for Amazon CloudFront is aws.cloudfront.

See also: http://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html#genref-aws-service-namespaces

time?

Type: string[] (optional, default: No filtering on time)

The event timestamp, which can be specified by the service originating the event.

If the event spans a time interval, the service might choose to report the start time, so this value can be noticeably before the time the event is actually received.

version?

Type: string[] (optional, default: No filtering on version)

By default, this is set to 0 (zero) in all events.

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