@aws-cdk/aws-sns

Amazon Simple Notification Service Construct Library

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Add an SNS Topic to your stack:

const topic = new sns.Topic(this, 'Topic', {
  displayName: 'Customer subscription topic',
});

Add a FIFO SNS topic with content-based de-duplication to your stack:

const topic = new sns.Topic(this, 'Topic', {
  contentBasedDeduplication: true,
  displayName: 'Customer subscription topic',
  fifo: true,
  topicName: 'customerTopic',
});

Note that FIFO topics require a topic name to be provided. The required .fifo suffix will be automatically added to the topic name if it is not explicitly provided.

Subscriptions

Various subscriptions can be added to the topic by calling the .addSubscription(...) method on the topic. It accepts a subscription object, default implementations of which can be found in the @aws-cdk/aws-sns-subscriptions package:

Add an HTTPS Subscription to your topic:

const myTopic = new sns.Topic(this, 'MyTopic');

myTopic.addSubscription(new subscriptions.UrlSubscription('https://foobar.com/'));

Subscribe a queue to the topic:

declare const queue: sqs.Queue;
const myTopic = new sns.Topic(this, 'MyTopic');

myTopic.addSubscription(new subscriptions.SqsSubscription(queue));

Note that subscriptions of queues in different accounts need to be manually confirmed by reading the initial message from the queue and visiting the link found in it.

Filter policy

A filter policy can be specified when subscribing an endpoint to a topic.

Example with a Lambda subscription:

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

const myTopic = new sns.Topic(this, 'MyTopic');
declare const fn: lambda.Function;

// Lambda should receive only message matching the following conditions on attributes:
// color: 'red' or 'orange' or begins with 'bl'
// size: anything but 'small' or 'medium'
// price: between 100 and 200 or greater than 300
// store: attribute must be present
myTopic.addSubscription(new subscriptions.LambdaSubscription(fn, {
  filterPolicy: {
    color: sns.SubscriptionFilter.stringFilter({
      allowlist: ['red', 'orange'],
      matchPrefixes: ['bl'],
    }),
    size: sns.SubscriptionFilter.stringFilter({
      denylist: ['small', 'medium'],
    }),
    price: sns.SubscriptionFilter.numericFilter({
      between: { start: 100, stop: 200 },
      greaterThan: 300,
    }),
    store: sns.SubscriptionFilter.existsFilter(),
  },
}));

Example of Firehose Subscription

import { DeliveryStream } from '@aws-cdk/aws-kinesisfirehose';

const topic = new sns.Topic(this, 'Topic');
declare const stream: DeliveryStream;

new sns.Subscription(this, 'Subscription', {
  topic,
  endpoint: stream.deliveryStreamArn,
  protocol: sns.SubscriptionProtocol.FIREHOSE,
  subscriptionRoleArn: "SAMPLE_ARN", //role with permissions to send messages to a firehose delivery stream
});

DLQ setup for SNS Subscription

CDK can attach provided Queue as DLQ for your SNS subscription. See the SNS DLQ configuration docs for more information about this feature.

Example of usage with user provided DLQ.

const topic = new sns.Topic(this, 'Topic');
const dlQueue = new sqs.Queue(this, 'DeadLetterQueue', {
  queueName: 'MySubscription_DLQ',
  retentionPeriod: Duration.days(14),
});

new sns.Subscription(this, 'Subscription', {
  endpoint: 'endpoint',
  protocol: sns.SubscriptionProtocol.LAMBDA,
  topic,
  deadLetterQueue: dlQueue,
});

CloudWatch Event Rule Target

SNS topics can be used as targets for CloudWatch event rules.

Use the @aws-cdk/aws-events-targets.SnsTopic:

import * as codecommit from '@aws-cdk/aws-codecommit';
import * as targets from '@aws-cdk/aws-events-targets';

declare const repo: codecommit.Repository;
const myTopic = new sns.Topic(this, 'Topic');

repo.onCommit('OnCommit', {
  target: new targets.SnsTopic(myTopic),
});

This will result in adding a target to the event rule and will also modify the topic resource policy to allow CloudWatch events to publish to the topic.

Topic Policy

A topic policy is automatically created when addToResourcePolicy is called, if one doesn't already exist. Using addToResourcePolicy is the simplest way to add policies, but a TopicPolicy can also be created manually.

const topic = new sns.Topic(this, 'Topic');
const topicPolicy = new sns.TopicPolicy(this, 'TopicPolicy', {
  topics: [topic],
});

topicPolicy.document.addStatements(new iam.PolicyStatement({
  actions: ["sns:Subscribe"],
  principals: [new iam.AnyPrincipal()],
  resources: [topic.topicArn],
}));

A policy document can also be passed on TopicPolicy construction

const topic = new sns.Topic(this, 'Topic');
const policyDocument = new iam.PolicyDocument({
  assignSids: true,
  statements: [
    new iam.PolicyStatement({
      actions: ["sns:Subscribe"],
      principals: [new iam.AnyPrincipal()],
      resources: [topic.topicArn],
    }),
  ],
});

const topicPolicy = new sns.TopicPolicy(this, 'Policy', {
  topics: [topic],
  policyDocument,
});