Hi team, this might be more of a python question. I am working on adding the prometheus monitoring for our sensors. I am actually planning to add a new decorator

@sensor_tracker

which can be added to all the sensors on top of the

@sensor

decorator to do metrics tracking. However, I might have to look into the sensor return result after calling the function to check if a sensor tick has yielded a run request or not. Looks like sensor is currently returning a generator which should be iterated in order to check for run request. Is there anyway I can do this safely without affecting the Dagster flow?

I’d recommend to populate the run request / skip reason / etc in order, i.e. keep the return type of

sensor_tracker

as a generator.

Thanks @yuhan. This is how I have implemented it right now, but I am seeing the below error. Any thoughts?

def sensor_tracker(sensor_type: SensorType, sensor_name: str):
    def call_sensor_and_track(func):
        def wrapper(*args, **kwargs):
            start_time = time.time()
            try:
                result = list(func(*args, **kwargs))
                gen, gen_return = tee(result)
                print("track success metric")
                return gen_return
            except Exception as e:
                print("track error metric")

        return wrapper

    return call_sensor_and_track

@sensor_tracker(sensor_type=SensorType.EVENT_SOURCE, sensor_name="name")
    @sensor(
        name="name",
        job=job,
        minimum_interval_seconds=180,
    )
    def check_sensor():
        yield SkipReason("Skipped")

Error:

File "/usr/local/lib/python3.7/site-packages/dagster/grpc/server.py", line 474, in StreamingExternalRepository
  serialized_external_repository_data = self._get_serialized_external_repository_data(request)
File "/usr/local/lib/python3.7/site-packages/dagster/grpc/server.py", line 464, in _get_serialized_external_repository_data
  external_repository_data_from_def(recon_repo.get_definition())
File "/usr/local/lib/python3.7/site-packages/dagster/core/host_representation/external_data.py", line 764, in external_repository_data_from_def
  list(map(external_sensor_data_from_def, repository_def.sensor_defs)),
File "/usr/local/lib/python3.7/site-packages/dagster/core/host_representation/external_data.py", line 976, in external_sensor_data_from_def
  first_target = sensor_def.targets[0] if sensor_def.targets else None
tributeError: 'function' object has no attribute 'targets'