SNS to SQS fanout pattern

Fanout pattern using SNS and SQS. Subscription filters are used to route SNS topics to the the correct SQS queue.

Three SQS queues subscribe to the SNS topic. The topic routing logic is defined through the subscription filter policy.

The AllMetricsSqsQueue queue receives all the messages. The TemperatureSqsQueue queue receives Temperature messages and the HumiditySqsQueue queue receives Humidity messages.

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: Serverless patterns - SNS to SQS Fanout pattern using SAM (uksb-1tthgi812) (tag:sns-sqs-fanout)


Resources:
  # The SNS topic where all metrics data will be published
  MetricsSnsTopic:
    Type: AWS::SNS::Topic
    Properties:
      DisplayName: MetricsSnsTopic
      TopicName: MetricsSnsTopic    

  # Define the SQS queues
  # AllMetricsSqsQueue will receive all the messages from SNS Topic
  AllMetricsSqsQueue:
    Type: AWS::SQS::Queue
    Properties: 
      QueueName: AllMetricsSqsQueue
      RedrivePolicy: 
        deadLetterTargetArn: !GetAtt MetricsSqsDLQueue.Arn
        maxReceiveCount: 5
  # TemperatureSqsQueue will receive only the temperature metrics data from SNS Topic        
  TemperatureSqsQueue:
    Type: AWS::SQS::Queue
    Properties: 
      QueueName: TemperatureSqsQueue
      RedrivePolicy: 
        deadLetterTargetArn: !GetAtt TemperatureSqsDLQueue.Arn
        maxReceiveCount: 5
  # HumiditySqsQueue will receive only the humidity metrics data from SNS Topic         
  HumiditySqsQueue:
    Type: AWS::SQS::Queue
    Properties: 
      QueueName: HumiditySqsQueue
      RedrivePolicy: 
        deadLetterTargetArn: !GetAtt HumiditySqsDLQueue.Arn
        maxReceiveCount: 5
  # Define the deal letter queues for each of the above three topics
  MetricsSqsDLQueue:
    Type: AWS::SQS::Queue
    Properties: 
      QueueName: MetricsSqsDLQueue
  TemperatureSqsDLQueue:
    Type: AWS::SQS::Queue
    Properties: 
      QueueName: TemperatureSqsDLQueue
  HumiditySqsDLQueue:
    Type: AWS::SQS::Queue
    Properties: 
      QueueName: HumiditySqsDLQueue

  # Define the policy that allows SNS to publish to this SQS queue
  SnsToSqsPolicy:
    Type: AWS::SQS::QueuePolicy
    Properties:
      PolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Sid: "Allow SNS publish to SQS"
            Effect: Allow
            Principal: 
              Service: "sns.amazonaws.com"
            Resource: "*"
            Action: 
              - sqs:SendMessage
            Condition:
              ArnEquals:
                aws:SourceArn: !Ref MetricsSnsTopic
      Queues:
        - !Ref AllMetricsSqsQueue
        - !Ref TemperatureSqsQueue
        - !Ref HumiditySqsQueue        

  # Define the SNS Subscriptions and Filter Policies
  # AllMetricsSqsQueue will receive all messages from the SNS Topic
  MetricsQueueSubscription:
    Type: AWS::SNS::Subscription
    Properties:
      Endpoint: !GetAtt AllMetricsSqsQueue.Arn
      Protocol: sqs
      RawMessageDelivery: True
      TopicArn: !Ref MetricsSnsTopic
  # TemperatureSqsQueue will receive only the messages which has message attribute MetricType = temperature from SNS Topic    
  TemperatureSqsQueueSubscription:
    Type: AWS::SNS::Subscription
    Properties:
      Endpoint: !GetAtt TemperatureSqsQueue.Arn
      Protocol: sqs
      FilterPolicy:
        MetricType:
          - Temperature
      RawMessageDelivery: True
      TopicArn: !Ref MetricsSnsTopic
  # HumiditySqsQueue will receive only the messages which has message attribute MetricType = humidity from SNS Topic  
  HumiditySqsQueueSubscription:
    Type: AWS::SNS::Subscription
    Properties:
      Endpoint: !GetAtt HumiditySqsQueue.Arn
      Protocol: sqs
      FilterPolicy:
        MetricType:
          - Humidity
      RawMessageDelivery: True
      TopicArn: !Ref MetricsSnsTopic

# List all common outputs for usage
Outputs:
  SNStopicName:
    Description: SNS topic name
    Value: !GetAtt MetricsSnsTopic.TopicName

  SNStopicARN:
    Description: SNS topic ARN
    Value: !Ref MetricsSnsTopic

  AllMetricsSqsQueueName:
    Description: SQS queue name
    Value: !GetAtt AllMetricsSqsQueue.QueueName

  AllMetricsSqsQueueArn:
    Description: SQS queue ARN
    Value: !GetAtt AllMetricsSqsQueue.Arn

  AllMetricsSqsQueueURL:
    Description: SQS queue URL
    Value: !Ref AllMetricsSqsQueue

  TemperatureSqsQueueName:
    Description: SQS queue name
    Value: !GetAtt TemperatureSqsQueue.QueueName

  TemperatureSqsQueueArn:
    Description: SQS queue ARN
    Value: !GetAtt TemperatureSqsQueue.Arn

  TemperatureSqsQueueURL:
    Description: SQS queue URL
    Value: !Ref TemperatureSqsQueue

  HumiditySqsQueueName:
    Description: SQS queue name
    Value: !GetAtt HumiditySqsQueue.QueueName

  HumiditySqsQueueArn:
    Description: SQS queue ARN
    Value: !GetAtt HumiditySqsQueue.Arn

  HumiditySqsQueueURL:
    Description: SQS queue URL
    Value: !Ref HumiditySqsQueue