template.yaml

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: Serverless S3 Uploader - upload files to S3 buckets from your web applications using pre-signed URLs.

# More info about Globals: https://github.com/awslabs/serverless-application-model/blob/master/docs/globals.rst
Globals:
  Api:
    # Allows any site to call these APIs (can restrict by replacing asterisk with site name)
    # Automatically adds AllowMethods with a list of methods for this API
    EndpointConfiguration: EDGE      
    Cors:
      AllowMethods: "'OPTIONS,GET'"
      AllowHeaders: "'Content-Type'"
      AllowOrigin: "'*'" 
  Function:
    Timeout: 5

Resources:
  S3Bucket:
    Type: AWS::S3::Bucket
    Properties:
      CorsConfiguration:
        CorsRules:
        - AllowedHeaders:
            - "*"
          AllowedMethods:
            - GET
            - PUT
            - POST
            - DELETE
            - HEAD
          AllowedOrigins:
            - "*"

  S3UploaderFunction:
    # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
    Type: AWS::Serverless::Function 
    Properties:
      CodeUri: s3UploaderFunction/
      Handler: app.handler
      Runtime: nodejs12.x
      MemorySize: 128
      Environment:
        Variables:
          UploadBucket: !Ref S3Bucket
      Policies:
        - S3CrudPolicy:
            BucketName: !Ref S3Bucket
      Events:
        HttpPost:
          Type: Api
          Properties:
            Path: '/'
            Method: get

Outputs:
  S3UploaderFunction:
    Description: "Lambda Function ARN"
    Value: !GetAtt S3UploaderFunction.Arn
  S3UploaderFunctionIamRole:
    Description: "Implicit IAM Role created for function"
    Value: !GetAtt S3UploaderFunctionRole.Arn
  S3BucketName:
    Description: S3 bucket
    Value: !Ref S3Bucket