How do you set up an API Gateway Step Function integration using Terraform and aws_apigatewayv2_integration

Question

I am looking for an example on how to start execution of a step function from API Gateway using Terraform and the aws_apigatewayv2_integration resource. I am using an HTTP API (have only found an older example for REST API's on Stackoverflow).

Currently I have this:

resource "aws_apigatewayv2_integration" "workflow_proxy_integration" {
  api_id                  = aws_apigatewayv2_api.default.id
  credentials_arn         = aws_iam_role.api_gateway_step_functions.arn
  integration_type        = "AWS_PROXY"
  integration_subtype     = "StepFunctions-StartExecution"
  description             = "The integration which will start the Step Functions workflow."
  payload_format_version  = "1.0"

  request_parameters = {
    StateMachineArn = aws_sfn_state_machine.default.arn
  }
}

Right now, my State Machine receives an empty input ("input": {}). When I try to add input to the request_parameters section, I get this error:

Error: error updating API Gateway v2 integration: BadRequestException: Parameter: input does not fit schema for Operation: StepFunctions-StartExecution.

Answer 1

I spent over an hour looking for a solution to a similar problem I was having with request_parameters. AWS's documentation currently uses camelCase for their keys in all of their examples (stateMachineArn, input, etc.) so it made it difficult to research.

You'll want to use PascalCase for your keys, similar to how you already did for StateMachineArn. So instead of input, you'll use Input.