Source code for airflow.providers.common.messaging.triggers.msg_queue

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from __future__ import annotations

from collections.abc import AsyncIterator
from functools import cached_property
from typing import Any

from airflow.exceptions import AirflowException
from airflow.providers.common.messaging.providers import MESSAGE_QUEUE_PROVIDERS
from airflow.triggers.base import BaseEventTrigger, TriggerEvent



[docs]
class MessageQueueTrigger(BaseEventTrigger):
    """
    ``MessageQueueTrigger`` serves as a unified trigger for monitoring message queues from different providers.

    It abstracts away provider-specific details, allowing users to monitor a queue with a single trigger,
    regardless of the underlying provider.

    This makes it easy to switch providers without modifying the trigger.

    :param queue: The queue identifier

    .. seealso::
        For more information on how to use this trigger, take a look at the guide:
        :ref:`howto/trigger:MessageQueueTrigger`
    """

    def __init__(self, *, queue: str, **kwargs: Any) -> None:

[docs]
        self.queue = queue


[docs]
        self.kwargs = kwargs


    @cached_property

[docs]
    def trigger(self) -> BaseEventTrigger:
        providers = [provider for provider in MESSAGE_QUEUE_PROVIDERS if provider.queue_matches(self.queue)]
        if len(providers) == 0:
            raise ValueError(f"The queue '{self.queue}' is not recognized by ``MessageQueueTrigger``.")
        if len(providers) > 1:
            self.log.error(
                "The queue '%s' is recognized by more than one provider. "
                "At least two providers in ``MESSAGE_QUEUE_PROVIDERS`` are colliding with each "
                "other.",
                self.queue,
            )
            raise AirflowException(f"The queue '{self.queue}' is recognized by more than one provider.")
        return providers[0].trigger_class()(
            **providers[0].trigger_kwargs(self.queue, **self.kwargs), **self.kwargs
        )



[docs]
    def serialize(self) -> tuple[str, dict[str, Any]]:
        return self.trigger.serialize()



[docs]
    async def run(self) -> AsyncIterator[TriggerEvent]:
        async for event in self.trigger.run():
            yield event