# Amazon SNS to Amazon SQS

This CDK template deploys a SNS topic and an SQS queue. The SQS queue is subscribed to the SNS topic. SNS invokes the SQS queue when new messages are available. When messages are sent to the SNS topic, they are delivered as a JSON event payload to the SQS queue.

Learn more about this pattern at Serverless Land Patterns: [serverlessland.com/patterns/sns-sqs-cdk](https://serverlessland.com/patterns/sns-sqs-cdk)

Important: this application uses various AWS services and there are costs associated with these services after the Free Tier usage - please see the [AWS Pricing page](https://aws.amazon.com/pricing/) for details. You are responsible for any AWS costs incurred. No warranty is implied in this example.

## Requirements

* [Create an AWS account](https://portal.aws.amazon.com/gp/aws/developer/registration/index.html) if you do not already have one and log in. The IAM user that you use must have sufficient permissions to make necessary AWS service calls and manage AWS resources.
* [AWS CLI](https://docs.aws.amazon.com/cli/latest/userguide/install-cliv2.html) installed and configured
* [Git Installed](https://git-scm.com/book/en/v2/Getting-Started-Installing-Git)
* [AWS Cloud Development Kit](https://docs.aws.amazon.com/cdk/latest/guide/getting_started.html) (AWS CDK >= 1.124.0) Installed

## Deployment Instructions

1. Create a new directory, navigate to that directory in a terminal and clone the GitHub repository:
    ``` 
    git clone https://github.com/aws-samples/serverless-patterns
    ```
2. Change directory to the pattern directory:
    ```
    cd sns-sqs-cdk
    ```
3. From the command line, use AWS CDK to deploy the AWS resources for the pattern as specified in the template.yml file:
    ```
    cdk deploy
    ```
4. Create a virtual environment for python:
    ```
    python3 -m venv .venv
    ```
5. Activate the virtual environment:
    ```
    source .venv/bin/activate
    ```
6. Install python modules:
    ```
    python3 -m pip install -r requirements.txt
    ```
7. From the command line, use CDK to synthesize the CloudFormation template and check for errors:
    ```
    cdk synth
    ```
8. From the command line, use CDK to deploy the stack:
    ```
    cdk deploy
    ```
9. Note the outputs from the CDK deployment process. This contains the SNS and SQS attributes used to test this deployment.

## Example event payload received by SQS

```
{
    "Messages": [
        {
            "MessageId": "12345678-fef2-4639-b269-123456789012",
            "ReceiptHandle": "123456/g66F9oFe9GjqvCV123456789012qXNQWhEPjaet123456789012P1Najh0B8L4v123456789012tMhDCW8+4HemB123456789012PzU2ZccaD+TRQA6eo123456789012FEz123456789012AeJt4q123456789012xVHh7nEtwEW6/123456789012a9uXzmVl123456789012YRr/slwbLOz3H41234567890129Okiu2rM12345678901231H/5wS123456789012SJsc6juhL5RLLtlJg7GyZcfekyHR7MpVOR123456789012pqh7pJNTa1nFZwfZS2Z123456789012Y0K5d+0xyglCvxfpmg+RzH0ZKIhxN123456789012Nn9PRiTl",
            "MD5OfBody": "12345678901280dcda123456789012",
            "Body": "{\n  \"Type\" : \"Notification\",\n  \"MessageId\" : \"12345678-be92-513a-a017-1234567890\",\n  \"TopicArn\" : \"arn:aws:sns:us-east-1:123456789012:patterns-sns-to-sqs-MySnsTopic-123456789012\",\n  
\"Subject\" : \"testSubject\",\n  \"Message\" : \"testMessage\",\n  \"Timestamp\" : \"2021-02-10T15:51:48.748Z\",\n  \"SignatureVersion\" : \"1\",\n  \"Signature\" : \"FMCq/123456789012+cHuU123456789012uge/123456789012/74VExy8A1234567890120LfxjMZvR123456789012pxk6YasI123456789012S7N/CM+qhHOs94lVfdu8zjauMMvRBfBL22qsU14iPB8DTHTuK766DT2IAh+eNTY123456789012u2c8D4gdzl123456789012rpqyf3j123456789012L+BIYpANf123456789012TjxeXNS+Mxh123456789012sq4cAjIqB7CA123456789012j+YpeK123456789012CMulNP282ME123456789012GjIUG6K65MKpA==\",\n  \"SigningCertURL\" : \"https://sns.us-east-1.amazonaws.com/SimpleNotificationService-12345678901236cd94b123456789012.pem\",\n  \"UnsubscribeURL\" 
: \"https://sns.us-east-1.amazonaws.com/?Action=Unsubscribe&SubscriptionArn=arn:aws:sns:us-east-1:123456789012:patterns-sns-to-sqs-MySnsTopic-123456789012:123456789-1745-440a-94a2-1234567890\"\n}"
        }
    ]
}
```
### Testing

Use the [AWS CLI](https://aws.amazon.com/cli/) to send a message to the SNS topic and observe the event delivered to the Lambda function:

1. Send the SNS message:

```bash
aws sns publish --topic-arn ENTER_SNS_TOPIC_ARN  --subject testSubject --message testMessage
```
2. Retrieve the message from the SQS queue, using the queue URL from the AWS CDK deployment outputs:
```bash
aws sqs receive-message --queue-url ENTER_YOUR_QUEUE_URL
```

## Cleanup
 
1. Delete the stack
    ```bash
    cdk destroy
    ```
----
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