(aws-stepfunctions): Support dynamic Task timeouts (TimeoutSecondsPath/HeartbeatSecondsPath)

Amazon States Language supports dynamic Task state timeout and heartbeat configurations by the TimeoutSecondsPath and HeartbeatSecondsPath properties respectively. TimeoutSecondsPath has the same effect as TimeoutSeconds but reads the seconds value at runtime from the state input using JSONPath. This is not supported in CDK without a CustomState.

• https://docs.aws.amazon.com/step-functions/latest/dg/amazon-states-language-task-state.html
• https://states-language.net/spec.html#task-state

Use Case

Allows CDK users to specify Task state timeout and heartbeat settings at runtime instead of hardcoding static values in the state machine definition.

Proposed Solution

• Option 1 - Expose explicit timeoutPath and heartbeatPath in TaskBaseProps

const myTask = new EcsRunTask(scope, "MyTask", {
    ...
    timeoutPath: JsonPath.numberAt("$.myTimeoutInSeconds")
    ...
});

// OR

const myTask = new EcsRunTask(scope, "MyTask", {
    ...
    timeoutPath: "$.myTimeoutInSeconds"
    ...
});

• Option 2 - Use the existing timeout and heartbeat properties and append “Path” to the generated ASL if the provided value is JSONPath, similar to how Parameters works in json-path.ts

const myTask = new EcsRunTask(scope, "MyTask", {
    ...
    timeout: JsonPath.numberAt("$.myTimeoutInSeconds")
    ...
});

Both would render the same ASL:

{
  "Type": "Task",
  "Resource": "...",
  ...
  "TimeoutSecondsPath": "$.myTimeoutInSeconds",
  ...
}

Other

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

---

This is a 🚀 Feature Request

[natenez]

+1 on this feature request. I am developing a new step function and need to use the heartbeatPath since a compile time heartbeat isn’t appropriate. I’ll give the work around a try until the feature is available.

[mzyil]

Here is a workaround that does not break the synth

  let renderer: any = LambdaInvoke.prototype["renderTaskBase"];
  LambdaInvoke.prototype["renderTaskBase"] = function () {
    let result = renderer.apply(this);
    let timeoutSecondsPath = (this as any)["timeoutSecondsPath"];
    if (timeoutSecondsPath) {
      result["TimeoutSecondsPath"] = timeoutSecondsPath;
    }
    return result;
  }

later

(theStep as any)["timeoutSecondsPath"] = JsonPath.stringAt("$.somePath")