[aws-stepfunctions-tasks] Unable to use the Wait for task Token: Task Token is missing in payload (pass Context.taskToken somewhere in payload)

❓ How to specify the task token + pass input on the payload with the RunLambdaTask

The Question

How can I specify a task that uses the wait for task token using CDK.

The README does not contain an example using the RunLambdaTask (https://github.com/aws/aws-cdk/tree/master/packages/%40aws-cdk/aws-stepfunctions-tasks#lambda) so I took the existing one and adapted like below

const reserveHotel = new sfn.Task(this, 'doX', {
      task: new tasks.RunLambdaTask(doXLambda, {
        integrationPattern: sfn.ServiceIntegrationPattern.WAIT_FOR_TASK_TOKEN,
        payload: sfn.TaskInput.fromObject({
          taskToken: "$$.Task.Token",
          input: "$"
        })
      }),
      resultPath: '$.Result'
    }).addCatch(otherTask, {
      resultPath: "$.Error"
    });

When trying to use cdk synth it complains “Task Token is missing in payload (pass Context.taskToken somewhere in payload)”. I’ve tried variations using the sfn.Context.taskToken but same result.

I guess it would be beneficial to update the ReadME to indicate the correct way of doing so.

Environment

• CDK CLI Version: 1.54.0 (build c01b9b9)
• Module Version: Not sure
• Node.js Version: 12.18.3
• OS: Ubuntu 20
• Language (Version): Typescript

Other information

[mariobittencourt]

payload: sfn.TaskInput.fromObject({
          token: sfn.JsonPath.taskToken,
          input: sfn.JsonPath.entirePayload
        })

Did the trick. I hope it is the right way.

[shivlaks]

@mariobittencourt great!

I should also mention the default should be the entire payload if you’re using LambdaInvoke. you shouldn’t need to explicitly specify it unless you’re selecting part of the state input.