feature: add ability to use waitForTaskToken for ECS tasks

Author: nicolaei

Diff for: src/stepfunctions/steps/compute.py

@@ -166,11 +166,12 @@ class EcsRunTaskStep(Task):
     Creates a Task State to run Amazon ECS or Fargate Tasks. See `Manage Amazon ECS or Fargate Tasks with Step Functions <https://docs.aws.amazon.com/step-functions/latest/dg/connect-ecs.html>`_ for more details.
     """
 
-    def __init__(self, state_id, wait_for_completion=True, **kwargs):
+    def __init__(self, state_id, wait_for_completion=True, wait_for_callback=False, **kwargs):
         """
         Args:
             state_id (str): State name whose length **must be** less than or equal to 128 unicode characters. State names **must be** unique within the scope of the whole state machine.
             wait_for_completion(bool, optional): Boolean value set to `True` if the Task state should wait for the ecs job to complete before proceeding to the next step in the workflow. Set to `False` if the Task state should submit the ecs job and proceed to the next step. (default: True)
+            wait_for_callback(bool, optional): Boolean value set to `True` if the Task state should wait for callback to resume the operation. (default: False)
             timeout_seconds (int, optional): Positive integer specifying timeout for the state in seconds. If the state runs longer than the specified timeout, then the interpreter fails the state with a `States.Timeout` Error Name. (default: 60)
             timeout_seconds_path (str, optional): Path specifying the state's timeout value in seconds from the state input. When resolved, the path must select a field whose value is a positive integer.
             heartbeat_seconds (int, optional): Positive integer specifying heartbeat timeout for the state in seconds. This value should be lower than the one specified for `timeout_seconds`. If more time than the specified heartbeat elapses between heartbeats from the task, then the interpreter fails the state with a `States.Timeout` Error Name.
@@ -181,7 +182,18 @@ def __init__(self, state_id, wait_for_completion=True, **kwargs):
             result_path (str, optional): Path specifying the raw input’s combination with or replacement by the state’s result. (default: '$')
             output_path (str, optional): Path applied to the state’s output after the application of `result_path`, producing the effective output which serves as the raw input for the next state. (default: '$')
         """
-        if wait_for_completion:
+        if wait_for_completion and wait_for_callback:
+            raise ValueError("Only one of wait_for_completion and wait_for_callback can be true")
+
+        if wait_for_callback:
+            """
+            Example resource arn: arn:aws:states:::ecs:runTask.waitForTaskToken
+            """
+
+            kwargs[Field.Resource.value] = get_service_integration_arn(ECS_SERVICE_NAME,
+                                                                       EcsApi.RunTask,
+                                                                       IntegrationPattern.WaitForTaskToken)
+        elif wait_for_completion:
             """
             Example resource arn: arn:aws:states:::ecs:runTask.sync
             """

Diff for: tests/unit/test_compute_steps.py

@@ -109,6 +109,14 @@ def test_ecs_run_task_step_creation():
         'End': True
     }
 
+    step = EcsRunTaskStep('Ecs Job', wait_for_callback=True)
+
+    assert step.to_dict() == {
+        'Type': 'Task',
+        'Resource': 'arn:aws:states:::ecs:runTask.waitForTaskToken',
+        'End': True
+    }
+
     step = EcsRunTaskStep('Ecs Job', parameters={
         'TaskDefinition': 'Task'
     })
@@ -121,3 +129,8 @@ def test_ecs_run_task_step_creation():
         },
         'End': True
     }
+
+    with pytest.raises(ValueError):
+        step = EcsRunTaskStep('Ecs Job',
+                              wait_for_completion=True,
+                              wait_for_callback=True)