SNS Not Publishing Message to SQS: A Comprehensive Troubleshooting Guide

Are you tired of scratching your head, wondering why SNS (Simple Notification Service) is not publishing messages to SQS (Simple Queue Service)? You’re not alone! This frustrating issue can bring your entire application to a grinding halt. Fear not, dear developer, for we’ve got you covered. In this article, we’ll delve into the possible causes and provide step-by-step solutions to get your SNS-SQS pipeline flowing smoothly.

Understanding the SNS-SQS Architecture

Before we dive into the troubleshooting process, it’s essential to understand how SNS and SQS interact. SNS is a fully managed messaging service that enables asynchronous communication between microservices, distributed systems, and serverless applications. SQS, on the other hand, is a message queuing service that decouples producers and consumers, allowing for fault-tolerant and scalable architectures.

  +---------------+
  |  SNS Topic   |
  +---------------+
           |
           |
           v
  +---------------+
  |  SNS Subscription  |
  |  (SQS Queue ARN)   |
  +---------------+
           |
           |
           v
  +---------------+
  |  SQS Queue    |
  +---------------+

Troubleshooting Steps

Let’s get started with the troubleshooting process. We’ll explore the most common causes of the issue and provide solutions to get your SNS-SQS pipeline up and running.

1. Check SNS Topic and Subscription Configuration

Ensure that your SNS topic and subscription are correctly configured. Verify the following:

• The SNS topic ARN is valid and exists in your AWS account.
• The SQS queue ARN is correctly subscribed to the SNS topic.
• The subscription is confirmed, and the status is set to “Enabled”.

If you find any issues with the configuration, update the relevant settings and try publishing a message again.

2. Verify SQS Queue Permissions

Check that the SQS queue has the necessary permissions to receive messages from SNS. Ensure that the SQS queue policy allows SNS to send messages to the queue.

{
  "Version": "2012-10-17",
  "Id": "arn:aws:sqs:REGION:ACCOUNT_ID:QUEUE_NAME/SQS_QUEUE_POLICY",
  "Statement": [
    {
      "Sid": " Allow-SNS-Publish",
      "Effect": "Allow",
      "Principal": "*",
      "Action": "sqs:SendMessage",
      "Resource": "arn:aws:sqs:REGION:ACCOUNT_ID:QUEUE_NAME",
      "Condition": {
        "ArnEquals": {
          "aws:SourceArn": "arn:aws:sns:REGION:ACCOUNT_ID:SNS_TOPIC_NAME"
        }
      }
    }
  ]
}

If the policy is not correctly configured, update the policy to include the necessary permissions.

3. Check SNS Topic Policy

Verify that the SNS topic policy allows publishing messages to the SQS queue. Ensure that the policy grants the necessary permissions to SNS to publish messages to the SQS queue.

{
  "Version": "2012-10-17",
  "Id": "arn:aws:sns:REGION:ACCOUNT_ID:SNS_TOPIC_NAME/SNS_TOPIC_POLICY",
  "Statement": [
    {
      "Sid": "Allow-Publish-To-SQS",
      "Effect": "Allow",
      "Principal": "*",
      "Action": "sns:Publish",
      "Resource": "arn:aws:sns:REGION:ACCOUNT_ID:SNS_TOPIC_NAME",
      "Condition": {
        "StringEquals": {
          "sns:Endpoint": "arn:aws:sqs:REGION:ACCOUNT_ID:QUEUE_NAME"
        }
      }
    }
  ]
}

If the policy is not correctly configured, update the policy to include the necessary permissions.

4. Investigate SNS Topic and SQS Queue Errors

Check the SNS topic and SQS queue error logs for any signs of issues. You can do this by:

• Enabling SNS topic and SQS queue metrics in CloudWatch.
• Checking the error logs in CloudWatch Logs.

Look for error messages that might indicate the cause of the issue. Common errors include:

• AccessDeniedException: The SQS queue policy doesn’t allow SNS to send messages.
• AuthorizationError: The SNS topic policy doesn’t allow publishing messages to the SQS queue.
• InvalidRequestException: The SNS topic or SQS queue ARN is invalid.

Address any errors you find, and try publishing a message again.

5. Verify IAM Roles and Permissions

Ensure that the IAM roles and permissions are correctly configured. Verify that the IAM role or user has the necessary permissions to publish messages to the SNS topic and SQS queue.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "Allow-SNS-Publish",
      "Effect": "Allow",
      "Action": "sns:Publish",
      "Resource": "arn:aws:sns:REGION:ACCOUNT_ID:SNS_TOPIC_NAME"
    },
    {
      "Sid": "Allow-SQS-ReceiveMessage",
      "Effect": "Allow",
      "Action": "sqs:ReceiveMessage",
      "Resource": "arn:aws:sqs:REGION:ACCOUNT_ID:QUEUE_NAME"
    }
  ]
}

If the IAM role or user lacks the necessary permissions, update the IAM policy to include the required permissions.

6. Check SNS Topic and SQS Queue Status

Verify that the SNS topic and SQS queue are in a healthy state. Check the status of the SNS topic and SQS queue in the AWS Management Console or using the AWS CLI.

aws sns get-topic-attributes --topic-arn arn:aws:sns:REGION:ACCOUNT_ID:SNS_TOPIC_NAME
aws sqs get-queue-attributes --queue-url https://sqs.REGION.amazonaws.com/ACCOUNT_ID/QUEUE_NAME

If the SNS topic or SQS queue is in a faulty state, address the underlying issue and try publishing a message again.

Conclusion

In this article, we’ve covered the most common causes of the “SNS not publishing message to SQS” issue and provided step-by-step solutions to help you troubleshoot and resolve the problem. By following these instructions, you should be able to identify and fix the issue, getting your SNS-SQS pipeline up and running smoothly.

Remember to always double-check your configuration, permissions, and policy settings to ensure that your SNS topic and SQS queue are correctly set up. If you’re still experiencing issues, don’t hesitate to reach out to AWS support or seek help from a qualified AWS expert.

Additional Resources

For more information on SNS and SQS, please refer to the following resources:

• AWS Documentation: Amazon SNS
• AWS Documentation: Amazon SQS
• AWS Blog: SNS and SQS tutorials and best practices

By mastering SNS and SQS, you can build scalable, fault-tolerant, and highly available applications that take advantage of the power of asynchronous messaging. Happy coding!

SNS Topic Status	SQS Queue Status
Enabled	Active
Disabled	Inactive
Deleted	Deleted

Note: The table above illustrates the possible states of an SNS topic and SQS queue.

Frequently Asked Question

Stuck with SNS not publishing messages to SQS? Don’t worry, we’ve got you covered! Here are some frequently asked questions to help you troubleshoot the issue: