How can I attach a dynamically partitioned asset sensor to an op for processing external assets?

To attach a dynamically partitioned asset sensor to an op for processing external assets, you would typically define a sensor that monitors the external asset and triggers a job or op when a new partition is detected. However, the documentation does not provide a direct example of attaching a dynamically partitioned asset sensor to an op. It does provide information on how to work with external assets and sensors in general. Here's a high-level approach based on the concepts from the documentation: 1. Define the External Asset: You would first declare your external asset using

AssetSpec

and

external_assets_from_specs

if you're dealing with an asset that is not materialized by Dagster but you want to track it within Dagster's asset catalog. 2. Create a Sensor: You would then define a sensor using the

@sensor

decorator. This sensor would be responsible for checking the external system for new partitions of the asset and triggering a run when it detects changes. 3. Trigger a Job or Op: When the sensor detects a new partition, it should trigger a job or op that processes the new partition. This can be done by returning a

RunRequest

from the sensor function, which includes the necessary run configuration for the job or op that processes the asset. 4. Use the Python API: If you need to backfill metadata or report events for the external asset, you can use the

report_runless_asset_event

method on the

DagsterInstance

to insert events directly from Dagster's Python API. Here is a simplified example based on the documentation's guidance:

python
from dagster import sensor, RunRequest, DagsterInstance, AssetMaterialization

# Assume 'my_external_asset_op' is an op that processes the external asset
from my_project import my_external_asset_op

@sensor(job=my_external_asset_op)
def my_external_asset_sensor(context):
    # Logic to check for new partitions in the external system
    new_partitions = check_for_new_partitions()

    if new_partitions:
        for partition in new_partitions:
            # Trigger a run for each new partition
            yield RunRequest(
                run_key=partition,  # Unique identifier for the run
                run_config={
                    # Include necessary run configuration for processing the partition
                },
            )

# Function to check for new partitions in the external system
def check_for_new_partitions():
    # Implement logic to detect new partitions
    pass

# Assuming you have a DagsterInstance
instance = DagsterInstance.get()

# Report an asset event without a run
instance.report_runless_asset_event(
    AssetMaterialization(
        "external_asset_partition", metadata={"partition": "new_partition"}
    )
)

Please note that this is a high-level exa