Creating a notifier

The BaseNotifier is an abstract class that provides a basic structure for sending notifications in Airflow using the various on_*__callback. It is intended for providers to extend and customize for their specific needs.

To extend the BaseNotifier class, you will need to create a new class that inherits from it. In this new class, you should override the notify method with your own implementation that sends the notification. The notify method takes in a single parameter, the Airflow context, which contains information about the current task and execution.

You can also set the template_fields attribute to specify which attributes should be rendered as templates.

Here’s an example of how you can create a Notifier class:

from airflow.notifications.basenotifier import BaseNotifier
from my_provider import send_message
class MyNotifier(BaseNotifier):
    template_fields = ("message",)
    def __init__(self, message):
        self.message = message
    def notify(self, context):
        # Send notification here, below is an example
        title = f"Task {context['task_instance'].task_id} failed"
        send_message(title, self.message)

Using a notifier

Once you have a notifier implementation, you can use it in your DAG definition by passing it as an argument to the on_*_callbacks. For example, you can use it with on_success_callback or on_failure_callback to send notifications based on the status of a task or a DAG run.

Here’s an example of using the above notifier:

from airflow import DAG
from myprovider.notifier import MyNotifier
from datetime import datetime
with DAG(
    dag_id="example_notifier",
    start_date=datetime(2022, 1, 1),
    schedule_interval=None,
    on_success_callback=MyNotifier(message="Success!"),
    on_failure_callback=MyNotifier(message="Failure!"),
):
    task = BashOperator(
        task_id="example_task",
        bash_command="exit 1",
        on_success_callback=MyNotifier(message="Task Succeeded!"),
    )

For a list of community-managed notifiers, see Notifications.