template.yaml

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: >
  S3 Triggers Demo

  Sample SAM Template for REPS&Co Demo -- S3 Triggers

Parameters:
  BucketNamePrefix:
    Type: String
    Default: reps-demo-triggers-bucket

# More info about Globals: https://github.com/awslabs/serverless-application-model/blob/master/docs/globals.rst
Globals:
  Function:
    Timeout: 3

Resources:
  SourceBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: !Sub "${BucketNamePrefix}-source-bucket"
  DestBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: !Sub "${BucketNamePrefix}-dest-bucket"
  S3TriggersFunction:
    Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
    Properties:
      CodeUri: s3_triggers/
      Handler: app.lambda_handler
      Runtime: python3.7
      Policies:
        - S3ReadPolicy:
            BucketName: !Sub "${BucketNamePrefix}-source-bucket"
        - S3CrudPolicy:
            BucketName: !Sub "${BucketNamePrefix}-dest-bucket"
      Environment:
        Variables:
          DestBucket: !Sub "${BucketNamePrefix}-dest-bucket"
      Events:
        ImageUpload:
          Type: S3
          Properties:
            Bucket: !Ref SourceBucket
            Events: s3:ObjectCreated:Put
  # https://github.com/awslabs/serverless-application-model/issues/300
  # had to add this resource, because without it, the Event Source wasn't displaying in Lambda Console
  LambdaInvokePermission:
    Type: 'AWS::Lambda::Permission'
    Properties:
      FunctionName: !GetAtt S3TriggersFunction.Arn
      Action: 'lambda:InvokeFunction'
      Principal: 's3.amazonaws.com'
      SourceAccount: !Sub ${AWS::AccountId}
      SourceArn: !GetAtt SourceBucket.Arn

Outputs:
  # ServerlessRestApi is an implicit API created out of Events key under Serverless::Function
  # Find out more about other implicit resources you can reference within SAM
  # https://github.com/awslabs/serverless-application-model/blob/master/docs/internals/generated_resources.rst#api
  SourceBucket:
    Description: "S3 Bucket name that will trigger a Lambda function upon new objects insertion"
    Value: !Ref SourceBucket
  DestBucket:
    Description: "S3 Bucket name that will store the modified versions of the images from the source bucket"
    Value: !Ref DestBucket
  S3TriggersFunction:
    Description: "S3 Triggers Lambda Function ARN"
    Value: !GetAtt S3TriggersFunction.Arn
  S3TriggersFunctionIamRole:
    Description: "Implicit IAM Role created for S3 Triggers function"
    Value: !GetAtt S3TriggersFunctionRole.Arn