stepfunctions-tasks: StepFunctionsStartExecution should add AWS_STEP_FUNCTIONS_STARTED_BY_EXECUTION_ID

[iOnline247]

It'd be nice to have a property that'll add the AWS_STEP_FUNCTIONS_STARTED_BY_EXECUTION_ID to the input payload.

Use Case

This will make it easy to add the AWS_STEP_FUNCTIONS_STARTED_BY_EXECUTION_ID to the input payload.

Proposed Solution

    const finalTransformExecution = new StepFunctionsStartExecution(
        scope,
        'Final Transform',
        {
            stateMachine: finalTransformSfn,
            integrationPattern: IntegrationPattern.RUN_JOB,
            // Proposed property, but horrible name. ;)
            addStartedById: true,
            outputPath: '$.Output',
        },
    );

Other

This would assist in removing some of the workarounds I've implemented to get this to work. #14777

• 👋 I may be able to implement this feature request
• ⚠️ This feature might incur a breaking change

---

This is a 🚀 Feature Request

[shivlaks]

@iOnline247 thanks for adding this feature request. I agree it would be useful to have native support for it.

[hassanazharkhan]

@shivlaks Can I pick this up?

[BenChaimberg]

@hassanazharkhan yes, please feel free to open a PR for this feature. I think an appropriate name for the property would be associateWithParent and it should default to true

[kaizencc]

I could be way off base here as I'm trying to understand stepfunctions as a whole still, but it seems odd to have both an input property and the proposed associateWithParent property on StepFunctionsStartExecutionProps. It also seems nontrivial to implement, since associateWithParent would then be tasked with modifying the input property (which may or may not exist).

Instead, would it make more sense to add a new static method in JsonPath like what we do for taskToken()?

aws-cdk/packages/@aws-cdk/aws-stepfunctions/lib/fields.ts

Lines 67 to 69 in 3e9f04d

	public static get taskToken(): string {
	return new JsonPathToken('$$.Task.Token').toString();
	}

Something like:

public static get executionId(): string {
  return new JsonPathToken('$$.Execution.Id').toString();
}

Then the interface would look like this:

const task = new StepFunctionsStartExecution(this, 'Task', {
  stateMachine,
  input: sfn.TaskInput.fromObject({
    AWS_STEP_FUNCTIONS_STARTED_BY_EXECUTION_ID: sfn.JsonPath.executionId,
    token: sfn.JsonPath.taskToken, // this is how taskToken is used in the tests
  }),
}

Tasktoken seems to be one of the other keys modeled in the input property so I figure it makes sense to follow the implementation for that. Am I missing anything here? Happy to take on this issue since I've already invested time in researching this. @BenChaimberg can you take a look?

[BenChaimberg]

I agree this is nontrivial, but I still think possible. We have information about whether TaskInput is from a constructed object or directly taken from a JSON path. This means we can decide whether or not to support associateWithParent based on what is passed in for input. Something like:

class StepFunctionsStartExecution {
  constructor(...) {
    // ...
    if (this.props.associateWithParent && this.props.input?.type !== sfn.InputType.OBJECT) {
      throw new Error('Could not associate child execution with parent execution because input is taken directly from a JSON path (or a value for the `input` property was not provided). Use `sfn.TaskInput.fromObject` instead');
    }
  }

  _renderTask(): any {
    let input: any;
    if (this.props.associateWithParent) {
      const associateWithParentEntry = {
        AWS_STEP_FUNCTIONS_STARTED_BY_EXECUTION_ID: sfn.JsonPath.stringAt('$$.Execution.Id'),
      };
      input = { ...this.props.input.value, ...associateWithParentEntry };
    } else {
      input = this.props.input ? this.props.input.value : sfn.TaskInput.fromJsonPathAt('$').value;
    }
    return {
      // ...
      Parameters: {
        Input: input,
        // ...,
     };
  }
}

I think a executionId static property of JsonPath is a great idea too! Just not a good replacement for this feature IMO

[kaizencc]

I can do that too! I was wary about associateWithParent along with a non Object input but throwing an error there makes so much sense.

[github-actions]

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