How Do I Create an AWS SNS Topic Policy?

Introduction

Creating an AWS SNS topic policy is essential for managing permissions and actions related to Simple Notification Service (SNS) topics. By defining a policy, you can specify who is allowed to access the SNS topic and under what conditions. This guide will walk you through the process of creating an SNS topic and attaching a policy to it using TypeScript and Pulumi, ensuring that your SNS topics are secure and accessible as per your requirements.

Step-by-Step Explanation

1. Create an SNS Topic:

   • Begin by defining an SNS topic using the aws_sns_topic resource. This will serve as the foundation for your notification system.

2. Get Current Account ID:

   • Use the aws.getCallerIdentityOutput() function to dynamically fetch the current AWS account ID. This is crucial for setting conditions in your policy.

3. Define the SNS Topic Policy:

   • Construct a policy document using aws.iam.getPolicyDocumentOutput(). This document outlines the actions (sns:Publish and sns:Subscribe) that are permitted and specifies the resources and conditions under which these actions are allowed.

4. Attach the Policy to the SNS Topic:

   • Utilize the aws_sns_topic_policy resource to attach the created policy to your SNS topic. This step ensures that the topic is governed by the defined permissions.

import * as pulumi from "@pulumi/pulumi";
import * as aws from "@pulumi/aws";

// Create an SNS topic
const example = new aws.sns.Topic("example", {name: "example-topic"});
// Data source to get the current account ID
const current = aws.getCallerIdentityOutput({});
// Define the SNS topic policy as a JSON document
const snsTopicPolicy = aws.iam.getPolicyDocumentOutput({
    statements: [{
        actions: [
            "sns:Publish",
            "sns:Subscribe",
        ],
        resources: [example.arn],
        principals: [{
            identifiers: ["*"],
            type: "AWS",
        }],
        conditions: [{
            test: "StringEquals",
            variable: "aws:SourceAccount",
            values: [current.apply(current => current.accountId)],
        }],
    }],
});
// Attach the policy to the SNS topic
const exampleTopicPolicy = new aws.sns.TopicPolicy("example", {
    arn: example.arn,
    policy: snsTopicPolicy.apply(snsTopicPolicy => snsTopicPolicy.json),
});

Key Points:

• The aws_sns_topic resource defines the SNS topic.
• The aws_iam_policy_document data source creates a policy allowing sns:Publish and sns:Subscribe actions.
• The aws_sns_topic_policy resource attaches the created policy to the SNS topic.
• Use the aws_caller_identity data source to dynamically fetch the account ID.

Conclusion

By following these steps, you can effectively create and manage an AWS SNS topic policy. This setup allows you to control access to your SNS topics, ensuring that only authorized actions are permitted. With this approach, you can maintain security and compliance within your AWS environment, while leveraging the powerful features of AWS SNS for your notification needs.