Failed to publish to SAR with Error: ResultPath being null

[alexcasalboni]

Description: If you deploy a AWS::Serverless::StateMachine with the AWS SAM CLI it works great, but you cannot publish this app/stack to SAR.

Steps to reproduce the issue:

1. Define a simple app with a AWS::Serverless::StateMachine in it
2. Run sam package and sam publish

Observed result:
App publication fails with this error:

Error: SAM template is invalid. It cannot be deployed using AWS CloudFormation due to the following validation error: /Resources/powerTuningStateMachine/Type/Definition/States/Cleaner/ResultPath 'null' values are not allowed in templates

Expected result:
I'd expect to app to be published successfully, or at least I'd expect SAM CLI to provide a meaningful error.

[jfuss]

@alexcasalboni From the error is seems like your template is invalid. SAR supports AWS::Serverless::StateMachine according to their docs: https://docs.aws.amazon.com/serverlessrepo/latest/devguide/list-supported-resources.html.

Can you provide the template (redacted parts if you need to)? It seems like a SAR issue or that your template is not valid.

[alexcasalboni]

@jfuss you can find the whole template here: https://github.com/alexcasalboni/aws-lambda-power-tuning/blob/917d021ce5188e75dee7e4bee0452122ce141769/template.yml

The error I get from SAR is about ResultPath being null, which is well documented and works fine when I deploy it.

[cccassidy]

I was just trying to deploy a stack with the same ResultPath: null setting that @alexcasalboni is using and initially saw that cfn-lint was throwing an error about the null value: E0000 Null value at line X. Came across this issue after searching and I was able to deploy my stack just fine with the null value as well. Maybe SAR is running cfn-lint or something similar and rejects on the error?

[cccassidy]

Found that the cfn-lint folks are tracking the linter issue, in case they are related.
aws-cloudformation/cfn-lint#1657

[nikgibbens]

This is still a problem with CloudFormation YAML templates in the state machine. It's 2022 and this problem has been around for 2 years. When can we expect a fix?

[kddejong]

The CloudFormation service doesn't support null values. cfn-lint would capture that error when parsing a template since its not supported by the CloudFormation service. The issue with cfn-lint is resolved and I don't believe its related.

the serverless transform should be converting this to a string (property) which makes the template valid for CloudFormation because the null is now in a string. You can look into cfn-lint issue above for more details on that conversion.

[xazhao]

Hello! I tried to reproduce this issue and I can publish to SAR with ResultPath: null in a state machine using following template. I believe this issue has been fixed.

AWSTemplateFormatVersion: "2010-09-09"
Transform: AWS::Serverless-2016-10-31
Description: >
  sam-app

  Sample SAM Template for sam-app

Metadata:
  AWS::ServerlessRepo::Application:
    Name: my-app
    Description: hello world
    Author: user1
    SpdxLicenseId: Apache-2.0
    Labels: ['tests']
    HomePageUrl: https://github.com/user1/my-app-project
    SemanticVersion: 0.0.1
    SourceCodeUrl: https://github.com/user1/my-app-project


Resources:
  MySampleStateMachine:
    Type: AWS::Serverless::StateMachine
    Properties:
      Definition:
        StartAt: MyLambdaState
        States:
          MyLambdaState:
            Type: Task
            Resource: ARN of a lambda function
            ResultPath: null
            End: true
      Role: ARN of an IAM Role

Close this issue for now and feel free to reopen if you have other questions