Implicit uploads¶

Some resource properties take an S3 location. If the template has a local path in one of these properties, cfnrain uploads the file and replaces the path with the S3 location. You do not need a directive. This is what aws cloudformation package does too.

Illustrative output

Uploads need AWS, so the output on this page is illustrative.

Example¶

Resources:
  Function:
    Type: AWS::Lambda::Function
    Properties:
      Runtime: python3.13
      Handler: index.main
      Role: !GetAtt FunctionRole.Arn
      Code: lambda-src

  Network:
    Type: AWS::CloudFormation::Stack
    Properties:
      TemplateURL: network.yaml

The packaged template:

Resources:
  Function:
    Type: AWS::Lambda::Function
    Properties:
      Runtime: python3.13
      Handler: index.main
      Role: !GetAtt FunctionRole.Arn
      Code:
        S3Bucket: rain-artifacts-123456789012-eu-west-1
        S3Key: 1b4844dacc843f09941c11c94f80981d3be8ae7578952c71e875ef7add37b1a7

  Network:
    Type: AWS::CloudFormation::Stack
    Properties:
      TemplateURL: https://rain-artifacts-123456789012-eu-west-1.s3.eu-west-1.amazonaws.com/d2a84f4b8b650937ec8f73cd8be2c74add5a911ba64df27458ed8229da804a26

Properties¶

Resource type	Property	Output
`AWS::ApiGateway::RestApi`	`BodyS3Location`	Object with `Bucket` and `Key`
`AWS::AppSync::FunctionConfiguration`	`RequestMappingTemplateS3Location`, `ResponseMappingTemplateS3Location`	S3 URI
`AWS::AppSync::GraphQLSchema`	`DefinitionS3Location`	S3 URI
`AWS::AppSync::Resolver`	`RequestMappingTemplateS3Location`, `ResponseMappingTemplateS3Location`	S3 URI
`AWS::CloudFormation::Stack`	`TemplateURL`	HTTPS URL. cfnrain packages the nested template first.
`AWS::ElasticBeanstalk::ApplicationVersion`	`SourceBundle`	Object with `S3Bucket` and `S3Key`
`AWS::Glue::Job`	`Command.ScriptLocation`	S3 URI
`AWS::Lambda::Function`	`Code`	Object with `S3Bucket` and `S3Key`, always zipped
`AWS::Lambda::LayerVersion`	`Content`	Object with `S3Bucket` and `S3Key`, always zipped
`AWS::Serverless::Api`	`DefinitionUri`	S3 URI
`AWS::Serverless::Application`	`Location`	HTTPS URL. cfnrain packages the nested template first.
`AWS::Serverless::Function`	`CodeUri`	S3 URI, always zipped
`AWS::Serverless::LayerVersion`	`ContentUri`	S3 URI, always zipped
`AWS::ServerlessRepo::Application`	`LicenseUrl`, `ReadmeUrl`	S3 URI
`AWS::StepFunctions::StateMachine`	`DefinitionS3Location`	Object with `Bucket` and `Key`

Rules¶

cfnrain only changes a value that is a plain string. A map, such as an existing S3Bucket and S3Key, stays as it is.
An S3 URI (s3://...) stays as it is. For the nested stack properties, an http:// or https:// URL stays as it is.
If the upload fails, for example because the path does not exist, cfnrain leaves the value as it is and shows no error. Run with --debug to see why. The nested stack properties are different: a missing nested template stops packaging.
Nested templates are packaged with all their directives and modules, then uploaded.

The AWS CLI also packages AWS::Include Location, AWS::Serverless::StateMachine DefinitionUri and AWS::CodeCommit::Repository Code.S3. cfnrain does not. Use !Rain::S3 for those.