Resources: FunctionOne: Type: AWS::Serverless::Function Properties: CodeUri: s3://sam-demo-bucket/thumbnails.zip Handler: index.generate_thumbails Runtime: nodejs12.x Events: ImageBucket: Type: S3 Properties: Bucket: Ref: Images Events: s3:ObjectCreated:* FunctionTwo: Type: AWS::Serverless::Function Properties: CodeUri: s3://sam-demo-bucket/thumbnails.zip Handler: index.generate_thumbails Runtime: nodejs12.x Events: ImageBucket: Type: S3 Properties: Bucket: Ref: Images Events: s3:ObjectCreated:* Images: Type: AWS::S3::Bucket Properties: PublicAccessBlockConfiguration: BlockPublicAcls: true BlockPublicPolicy: true IgnorePublicAcls: true RestrictPublicBuckets: true