New Serverless Pattern - DLQ - Cloudwatch - SNS

dlq-cloudwatch-sns/Readme.md

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+# SQS Dead Letter Queue with CloudWatch Alarm and SNS Notification
+
+This pattern creates an Amazon SQS Dead Letter Queue (DLQ) that is monitored by CloudWatch. When more than 3 messages accumulate in the DLQ, a CloudWatch Alarm triggers and sends a notification through SNS.
+
+Learn more about this pattern at Serverless Land Patterns: https://serverlessland.com/patterns/sqs-dlq-cloudwatch-sns
+
+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.
+
+## 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)
+
+## 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 sqs-dlq-cloudwatch-sns
+    ```
+3. From the command line, use AWS SAM to deploy the AWS resources for the pattern as specified in the template.yml file:
+    ```
+    sam deploy --guided
+    ```
+4. During the prompts:
+    * Enter a stack name
+    * Enter the desired AWS Region
+    * Allow SAM CLI to create IAM roles with the required permissions.
+
+    Once you have run `sam deploy --guided` mode once and saved arguments to a configuration file (samconfig.toml), you can use `sam deploy` in future to use these defaults.
+
+5. Note the outputs from the SAM deployment process. These contain the resource names and/or ARNs which are used for testing.
+
+## How it works
+
+This pattern deploys an Amazon SQS queue as a Dead Letter Queue (DLQ), a CloudWatch alarm that monitors the number of messages in the DLQ, and an SNS topic that receives notifications when the alarm triggers. When more than 3 messages accumulate in the DLQ, the CloudWatch alarm will trigger and send a notification through SNS.
+
+## Testing
+
+1. Subscribe to the SNS topic created by the stack (you can find the ARN in the stack outputs)
+2. Send more than 3 messages to the DLQ
+3. Wait for approximately 5 minutes (the CloudWatch alarm evaluation period)
+4. You should receive a notification through SNS
+
+## Cleanup
+
+1. Delete the stack
+    ```bash
+    aws cloudformation delete-stack --stack-name STACK_NAME
+    ```
+2. Confirm the stack has been deleted
+    ```bash
+    aws cloudformation list-stacks --query "StackSummaries[?contains(StackName,'STACK_NAME')].StackStatus"
+    ```
+
+## Contributing
+
+We welcome community contributions! Please refer to [CONTRIBUTING.md](./CONTRIBUTING.md) for guidelines.
+
+## Resources
+
+* [AWS SQS Documentation](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/welcome.html)
+* [AWS CloudWatch Documentation](https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/WhatIsCloudWatch.html)
+* [AWS SNS Documentation](https://docs.aws.amazon.com/sns/latest/dg/welcome.html)

dlq-cloudwatch-sns/dlq.yaml

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+AWSTemplateFormatVersion: '2010-09-09'
+Description: 'Template to create SQS DLQ with CloudWatch Alarm and SNS notification'
+
+Resources:
+  # First, create the SNS Topic that will receive the alarm notification
+  AlertSNSTopic:
+    Type: 'AWS::SNS::Topic'
+    Properties:
+      DisplayName: 'DLQ-Alert-Topic'
+      TopicName: 'DLQ-Alert-Topic'
+
+  # Create the Dead Letter Queue
+  DeadLetterQueue:
+    Type: 'AWS::SQS::Queue'
+    Properties:
+      QueueName: 'MyDeadLetterQueue'
+      MessageRetentionPeriod: 1209600  # 14 days in seconds
+
+  # Create the CloudWatch Alarm
+  DLQAlarm:
+    Type: 'AWS::CloudWatch::Alarm'
+    Properties:
+      AlarmName: 'DLQ-Messages-Alarm'
+      AlarmDescription: 'Alarm when there are more than 3 messages in DLQ'
+      MetricName: 'ApproximateNumberOfMessagesVisible'
+      Namespace: 'AWS/SQS'
+      Dimensions:
+        - Name: QueueName
+          Value: !GetAtt DeadLetterQueue.QueueName
+      Statistic: 'Sum'
+      Period: 300  # 5 minutes
+      EvaluationPeriods: 1
+      Threshold: 3
+      ComparisonOperator: 'GreaterThanThreshold'
+      AlarmActions:
+        - !Ref AlertSNSTopic
+
+Outputs:
+  DLQUrl:
+    Description: 'URL of the Dead Letter Queue'
+    Value: !Ref DeadLetterQueue
+  DLQArn:
+    Description: 'ARN of the Dead Letter Queue'
+    Value: !GetAtt DeadLetterQueue.Arn
+  SNSTopicArn:
+    Description: 'ARN of the SNS Topic'
+    Value: !Ref AlertSNSTopic