sam_s3_lambda_template.yml

Resources:
  ImagesBucket:
    Type: AWS::S3::Bucket

  ResizeQueue:
    Type: AWS::SQS::Queue

  S3ToSQS:
    Type: AWS::S3::Bucket
    Properties:
      NotificationConfiguration:
        QueueConfigurations:
          - Event: s3:ObjectCreated:*
            Queue: !GetAtt ResizeQueue.Arn
    DependsOn: ImagesBucket  # wire notifications to the same bucket
    # (In practice, attach this config to ImagesBucket; shown split for brevity)

  ImageResizer:
    Type: AWS::Serverless::Function
    Properties:
      Runtime: python3.11
      Handler: app.handler
      Events:
        FromQueue:
          Type: SQS
          Properties:
            Queue: !GetAtt ResizeQueue.Arn
      Policies:
        - S3ReadPolicy:
            BucketName: !Ref ImagesBucket
        - S3WritePolicy:
            BucketName: !Ref ImagesBucket