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"""
Example Airflow DAG that uses Google PubSub services.
"""
import os
from datetime import datetime
from airflow import models
from airflow.operators.bash import BashOperator
from airflow.providers.google.cloud.operators.pubsub import (
PubSubCreateSubscriptionOperator,
PubSubCreateTopicOperator,
PubSubDeleteSubscriptionOperator,
PubSubDeleteTopicOperator,
PubSubPublishMessageOperator,
PubSubPullOperator,
)
from airflow.providers.google.cloud.sensors.pubsub import PubSubPullSensor
[docs]START_DATE = datetime(2021, 1, 1)
[docs]GCP_PROJECT_ID = os.environ.get("GCP_PROJECT_ID", "your-project-id")
[docs]TOPIC_FOR_SENSOR_DAG = os.environ.get("GCP_PUBSUB_SENSOR_TOPIC", "PubSubSensorTestTopic")
[docs]TOPIC_FOR_OPERATOR_DAG = os.environ.get("GCP_PUBSUB_OPERATOR_TOPIC", "PubSubOperatorTestTopic")
[docs]MESSAGE = {"data": b"Tool", "attributes": {"name": "wrench", "mass": "1.3kg", "count": "3"}}
# [START howto_operator_gcp_pubsub_pull_messages_result_cmd]
[docs]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 models.DAG(
"example_gcp_pubsub_sensor",
schedule_interval='@once', # Override to match your needs
start_date=START_DATE,
catchup=False,
) as example_sensor_dag:
# [START howto_operator_gcp_pubsub_create_topic]
[docs] create_topic1 = PubSubCreateTopicOperator(
task_id="create_topic", topic=TOPIC_FOR_SENSOR_DAG, project_id=GCP_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=GCP_PROJECT_ID, topic=TOPIC_FOR_SENSOR_DAG
)
# [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=GCP_PROJECT_ID,
subscription=subscription,
)
# [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_publish]
publish_task = PubSubPublishMessageOperator(
task_id="publish_task",
project_id=GCP_PROJECT_ID,
topic=TOPIC_FOR_SENSOR_DAG,
messages=[MESSAGE] * 10,
)
# [END howto_operator_gcp_pubsub_publish]
# [START howto_operator_gcp_pubsub_unsubscribe]
unsubscribe_task = PubSubDeleteSubscriptionOperator(
task_id="unsubscribe_task",
project_id=GCP_PROJECT_ID,
subscription=subscription,
)
# [END howto_operator_gcp_pubsub_unsubscribe]
# [START howto_operator_gcp_pubsub_delete_topic]
delete_topic = PubSubDeleteTopicOperator(
task_id="delete_topic", topic=TOPIC_FOR_SENSOR_DAG, project_id=GCP_PROJECT_ID
)
# [END howto_operator_gcp_pubsub_delete_topic]
create_topic1 >> subscribe_task >> publish_task
pull_messages >> pull_messages_result >> unsubscribe_task >> delete_topic
# Task dependencies created via `XComArgs`:
# subscribe_task >> pull_messages
# subscribe_task >> unsubscribe_task
with models.DAG(
"example_gcp_pubsub_operator",
schedule_interval='@once', # Override to match your needs
start_date=START_DATE,
catchup=False,
) as example_operator_dag:
# [START howto_operator_gcp_pubsub_create_topic]
[docs] create_topic2 = PubSubCreateTopicOperator(
task_id="create_topic", topic=TOPIC_FOR_OPERATOR_DAG, project_id=GCP_PROJECT_ID
)
# [END howto_operator_gcp_pubsub_create_topic]
# [START howto_operator_gcp_pubsub_create_subscription]
subscribe_task = PubSubCreateSubscriptionOperator(
task_id="subscribe_task", project_id=GCP_PROJECT_ID, topic=TOPIC_FOR_OPERATOR_DAG
)
# [END howto_operator_gcp_pubsub_create_subscription]
# [START howto_operator_gcp_pubsub_pull_message_with_operator]
subscription = subscribe_task.output
pull_messages_operator = PubSubPullOperator(
task_id="pull_messages",
ack_messages=True,
project_id=GCP_PROJECT_ID,
subscription=subscription,
)
# [END howto_operator_gcp_pubsub_pull_message_with_operator]
# [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_publish]
publish_task = PubSubPublishMessageOperator(
task_id="publish_task",
project_id=GCP_PROJECT_ID,
topic=TOPIC_FOR_OPERATOR_DAG,
messages=[MESSAGE, MESSAGE, MESSAGE],
)
# [END howto_operator_gcp_pubsub_publish]
# [START howto_operator_gcp_pubsub_unsubscribe]
unsubscribe_task = PubSubDeleteSubscriptionOperator(
task_id="unsubscribe_task",
project_id=GCP_PROJECT_ID,
subscription=subscription,
)
# [END howto_operator_gcp_pubsub_unsubscribe]
# [START howto_operator_gcp_pubsub_delete_topic]
delete_topic = PubSubDeleteTopicOperator(
task_id="delete_topic", topic=TOPIC_FOR_OPERATOR_DAG, project_id=GCP_PROJECT_ID
)
# [END howto_operator_gcp_pubsub_delete_topic]
(
create_topic2
>> subscribe_task
>> publish_task
>> pull_messages_operator
>> pull_messages_result
>> unsubscribe_task
>> delete_topic
)
# Task dependencies created via `XComArgs`:
# subscribe_task >> pull_messages_operator
# subscribe_task >> unsubscribe_task
