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"""
Example Airflow DAG that uses Google PubSub services.
"""
from __future__ import annotations
import os
from datetime import datetime
from airflow.models.dag import DAG
from airflow.providers.google.cloud.operators.pubsub import (
PubSubCreateSubscriptionOperator,
PubSubCreateTopicOperator,
PubSubDeleteSubscriptionOperator,
PubSubDeleteTopicOperator,
PubSubPublishMessageOperator,
PubSubPullOperator,
)
from airflow.providers.google.cloud.sensors.pubsub import PubSubPullSensor
from airflow.providers.standard.operators.bash import BashOperator
try:
from airflow.sdk import TriggerRule
except ImportError:
# Compatibility for Airflow < 3.1
from airflow.utils.trigger_rule import TriggerRule # type: ignore[no-redef,attr-defined]
ENV_ID = os.environ.get("SYSTEM_TESTS_ENV_ID", "default")
PROJECT_ID = os.environ.get("SYSTEM_TESTS_GCP_PROJECT", "default")
DAG_ID = "pubsub"
TOPIC_ID = f"topic-{DAG_ID}-{ENV_ID}"
MESSAGE = {"data": b"Tool", "attributes": {"name": "wrench", "mass": "1.3kg", "count": "3"}}
MESSAGE_TWO = {"data": b"Tool", "attributes": {"name": "wrench", "mass": "1.2kg", "count": "2"}}
# [START howto_operator_gcp_pubsub_pull_messages_result_cmd]
echo_cmd = """
{% for m in task_instance.xcom_pull('pull_messages') %}
echo "AckID: {{ m.get('ackId') }}, Base64-Encoded: {{ m.get('message') }}"
{% endfor %}
"""
# [END howto_operator_gcp_pubsub_pull_messages_result_cmd]
with DAG(
DAG_ID,
schedule="@once", # Override to match your needs
start_date=datetime(2021, 1, 1),
catchup=False,
) as dag:
# [START howto_operator_gcp_pubsub_create_topic]
create_topic = PubSubCreateTopicOperator(
task_id="create_topic", topic=TOPIC_ID, project_id=PROJECT_ID, fail_if_exists=False
)
# [END howto_operator_gcp_pubsub_create_topic]
# [START howto_operator_gcp_pubsub_create_subscription]
subscribe_task = PubSubCreateSubscriptionOperator(
task_id="subscribe_task", project_id=PROJECT_ID, topic=TOPIC_ID
)
# [END howto_operator_gcp_pubsub_create_subscription]
# [START howto_operator_gcp_pubsub_pull_message_with_sensor]
subscription = subscribe_task.output
pull_messages = PubSubPullSensor(
task_id="pull_messages",
ack_messages=True,
project_id=PROJECT_ID,
subscription=subscription,
return_immediately=False,
)
# [END howto_operator_gcp_pubsub_pull_message_with_sensor]
# [START howto_operator_gcp_pubsub_pull_messages_result]
pull_messages_result = BashOperator(task_id="pull_messages_result", bash_command=echo_cmd)
# [END howto_operator_gcp_pubsub_pull_messages_result]
# [START howto_operator_gcp_pubsub_pull_message_with_operator]
# return_immediately=False makes this pull block for a bounded, server-side period, holding the
# worker slot; pass return_immediately=True explicitly if the task should return an empty list
# instead of waiting.
pull_messages_operator = PubSubPullOperator(
task_id="pull_messages_operator",
ack_messages=True,
project_id=PROJECT_ID,
subscription=subscription,
return_immediately=False,
)
# [END howto_operator_gcp_pubsub_pull_message_with_operator]
# [START howto_operator_gcp_pubsub_publish]
publish_task = PubSubPublishMessageOperator(
task_id="publish_task",
project_id=PROJECT_ID,
topic=TOPIC_ID,
messages=[MESSAGE, MESSAGE],
)
# [END howto_operator_gcp_pubsub_publish]
publish_task2 = PubSubPublishMessageOperator(
task_id="publish_task2",
project_id=PROJECT_ID,
topic=TOPIC_ID,
messages=[MESSAGE_TWO, MESSAGE_TWO],
)
# [START howto_operator_gcp_pubsub_unsubscribe]
unsubscribe_task = PubSubDeleteSubscriptionOperator(
task_id="unsubscribe_task",
project_id=PROJECT_ID,
subscription=subscription,
)
# [END howto_operator_gcp_pubsub_unsubscribe]
unsubscribe_task.trigger_rule = TriggerRule.ALL_DONE
# [START howto_operator_gcp_pubsub_delete_topic]
delete_topic = PubSubDeleteTopicOperator(task_id="delete_topic", topic=TOPIC_ID, project_id=PROJECT_ID)
# [END howto_operator_gcp_pubsub_delete_topic]
delete_topic.trigger_rule = TriggerRule.ALL_DONE
(
create_topic
>> subscribe_task
>> publish_task
>> pull_messages
>> pull_messages_result
>> publish_task2
>> pull_messages_operator
>> unsubscribe_task
>> delete_topic
)
# Task dependencies created via `XComArgs`:
# subscribe_task >> pull_messages
# subscribe_task >> pull_messages_operator
# subscribe_task >> unsubscribe_task
# ### Everything below this line is not part of example ###
# ### Just for system tests purpose ###
from tests_common.test_utils.watcher import watcher
# This test needs watcher in order to properly mark success/failure
# when "tearDown" task with trigger rule is part of the DAG
list(dag.tasks) >> watcher()
from tests_common.test_utils.system_tests import get_test_run # noqa: E402
# Needed to run the example DAG with pytest (see: contributing-docs/testing/system_tests.rst)
test_run = get_test_run(dag)