Step Function definition in Terraform (Yaml)

Question

I have already implemented SFn in Terraform (JSON) file:

data "template_file" "sfn-definition" {
  template = file("step-function-definition.json")
}

resource "aws_sfn_state_machine" "sfn_state_machine" {
   name = "integration-step-function"
   role_arn = aws_iam_role.step_function_role.arn
   definition = data.template_file.sfn-definition.rendered
}

It's working fine, but instead of JSON, I would like to use YAML definition. I created the same SFn definition in YAML. I did it in AWS Toolkit (VS Code) and the graph is rendered correctly. I change JSON file to YAML:

template = file("step-function-definition.yaml")

And unfortunately it not works:

08:58:39  Error: Error creating Step Function State Machine: InvalidDefinition: 
Invalid State Machine Definition: 'INVALID_JSON_DESCRIPTION: 
Unrecognized token 'StartAt': was expecting (JSON String, Number, Array, Object or token 'null', 'true' or 'false')

I suppose that definition in aws_sfn_state_machine expect JSON file, but is there any option to define SFn in YAML and use Terraform?

Answer 1

Amazon States Language is JSON-based. So you have to convert your yaml to json first. You can try the following:

template = jsonencode(yamldecode(file("step-function-definition.yaml")))