Source code for airflow.providers.redis.sensors.redis_pub_sub

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from typing import TYPE_CHECKING, List, Sequence, Union

from airflow.providers.redis.hooks.redis import RedisHook
from airflow.sensors.base import BaseSensorOperator

if TYPE_CHECKING:
    from airflow.utils.context import Context


[docs]class RedisPubSubSensor(BaseSensorOperator):
    """
    Redis sensor for reading a message from pub sub channels

    :param channels: The channels to be subscribed to (templated)
    :param redis_conn_id: the redis connection id
    """

[docs]    template_fields: Sequence[str] = ('channels',)
[docs]    ui_color = '#f0eee4'

    def __init__(self, *, channels: Union[List[str], str], redis_conn_id: str, **kwargs) -> None:
        super().__init__(**kwargs)
        self.channels = channels
        self.redis_conn_id = redis_conn_id
        self.pubsub = RedisHook(redis_conn_id=self.redis_conn_id).get_conn().pubsub()
        self.pubsub.subscribe(self.channels)

[docs]    def poke(self, context: 'Context') -> bool:
        """
        Check for message on subscribed channels and write to xcom the message with key ``message``

        An example of message ``{'type': 'message', 'pattern': None, 'channel': b'test', 'data': b'hello'}``

        :param context: the context object
        :return: ``True`` if message (with type 'message') is available or ``False`` if not
        """
        self.log.info('RedisPubSubSensor checking for message on channels: %s', self.channels)

        message = self.pubsub.get_message()
        self.log.info('Message %s from channel %s', message, self.channels)

        # Process only message types
        if message and message['type'] == 'message':

            context['ti'].xcom_push(key='message', value=message)
            self.pubsub.unsubscribe(self.channels)

            return True

        return False