Source code for airflow.example_dags.example_asset_alias

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"""
Example DAG for demonstrating the behavior of the AssetAlias feature in Airflow, including conditional and
asset expression-based scheduling.

Notes on usage:

Turn on all the DAGs.

Before running any DAG, the schedule of the "asset_alias_example_alias_consumer" DAG will show as "Unresolved AssetAlias".
This is expected because the asset alias has not been resolved into any asset yet.

Once the "asset_s3_bucket_producer" DAG is triggered, the "asset_s3_bucket_consumer" DAG should be triggered upon completion.
This is because the asset alias "example-alias" is used to add an asset event to the asset "s3://bucket/my-task"
during the "produce_asset_events_through_asset_alias" task.
As the DAG "asset-alias-consumer" relies on asset alias "example-alias" which was previously unresolved,
the DAG "asset-alias-consumer" (along with all the DAGs in the same file) will be re-parsed and
thus update its schedule to the asset "s3://bucket/my-task" and will also be triggered.
"""

from __future__ import annotations

import pendulum

from airflow import DAG
from airflow.assets import Asset, AssetAlias
from airflow.decorators import task

with DAG(
    dag_id="asset_s3_bucket_producer",
    start_date=pendulum.datetime(2021, 1, 1, tz="UTC"),
    schedule=None,
    catchup=False,
    tags=["producer", "asset"],
):

    @task(outlets=[Asset("s3://bucket/my-task")])

[docs]    def produce_asset_events():
        pass


    produce_asset_events()

with DAG(
    dag_id="asset_alias_example_alias_producer",
    start_date=pendulum.datetime(2021, 1, 1, tz="UTC"),
    schedule=None,
    catchup=False,
    tags=["producer", "asset-alias"],
):

    @task(outlets=[AssetAlias("example-alias")])

[docs]    def produce_asset_events_through_asset_alias(*, outlet_events=None):
        bucket_name = "bucket"
        object_path = "my-task"
        outlet_events["example-alias"].add(Asset(f"s3://{bucket_name}/{object_path}"))


    produce_asset_events_through_asset_alias()

with DAG(
    dag_id="asset_s3_bucket_consumer",
    start_date=pendulum.datetime(2021, 1, 1, tz="UTC"),
    schedule=[Asset("s3://bucket/my-task")],
    catchup=False,
    tags=["consumer", "asset"],
):

    @task

[docs]    def consume_asset_event():
        pass


    consume_asset_event()

with DAG(
    dag_id="asset_alias_example_alias_consumer",
    start_date=pendulum.datetime(2021, 1, 1, tz="UTC"),
    schedule=[AssetAlias("example-alias")],
    catchup=False,
    tags=["consumer", "asset-alias"],
):

    @task(inlets=[AssetAlias("example-alias")])

[docs]    def consume_asset_event_from_asset_alias(*, inlet_events=None):
        for event in inlet_events[AssetAlias("example-alias")]:
            print(event)


    consume_asset_event_from_asset_alias()

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