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"""This module contains Google Cloud Pubsub triggers."""
from __future__ import annotations
import asyncio
from typing import TYPE_CHECKING, Any, AsyncIterator, Callable, Sequence
from airflow.providers.google.cloud.hooks.pubsub import PubSubAsyncHook
from airflow.triggers.base import BaseTrigger, TriggerEvent
if TYPE_CHECKING:
from google.cloud.pubsub_v1.types import ReceivedMessage
from airflow.utils.context import Context
[docs]class PubsubPullTrigger(BaseTrigger):
"""
Initialize the Pubsub Pull Trigger with needed parameters.
:param project_id: the Google Cloud project ID for the subscription (templated)
:param subscription: the Pub/Sub subscription name. Do not include the full subscription path.
:param max_messages: The maximum number of messages to retrieve per
PubSub pull request
:param ack_messages: If True, each message will be acknowledged
immediately rather than by any downstream tasks
:param gcp_conn_id: Reference to google cloud connection id
:param messages_callback: (Optional) Callback to process received messages.
Its return value will be saved to XCom.
If you are pulling large messages, you probably want to provide a custom callback.
If not provided, the default implementation will convert `ReceivedMessage` objects
into JSON-serializable dicts using `google.protobuf.json_format.MessageToDict` function.
:param poke_interval: polling period in seconds to check for the status
:param impersonation_chain: Optional service account to impersonate using short-term
credentials, or chained list of accounts required to get the access_token
of the last account in the list, which will be impersonated in the request.
If set as a string, the account must grant the originating account
the Service Account Token Creator IAM role.
If set as a sequence, the identities from the list must grant
Service Account Token Creator IAM role to the directly preceding identity, with first
account from the list granting this role to the originating account (templated).
"""
def __init__(
self,
project_id: str,
subscription: str,
max_messages: int,
ack_messages: bool,
gcp_conn_id: str,
messages_callback: Callable[[list[ReceivedMessage], Context], Any] | None = None,
poke_interval: float = 10.0,
impersonation_chain: str | Sequence[str] | None = None,
):
super().__init__()
self.project_id = project_id
self.subscription = subscription
self.max_messages = max_messages
self.ack_messages = ack_messages
self.messages_callback = messages_callback
self.poke_interval = poke_interval
self.gcp_conn_id = gcp_conn_id
self.impersonation_chain = impersonation_chain
self.hook = PubSubAsyncHook()
[docs] def serialize(self) -> tuple[str, dict[str, Any]]:
"""Serialize PubsubPullTrigger arguments and classpath."""
return (
"airflow.providers.google.cloud.triggers.pubsub.PubsubPullTrigger",
{
"project_id": self.project_id,
"subscription": self.subscription,
"max_messages": self.max_messages,
"ack_messages": self.ack_messages,
"messages_callback": self.messages_callback,
"poke_interval": self.poke_interval,
"gcp_conn_id": self.gcp_conn_id,
"impersonation_chain": self.impersonation_chain,
},
)
[docs] async def run(self) -> AsyncIterator[TriggerEvent]: # type: ignore[override]
try:
pulled_messages = None
while True:
if pulled_messages:
if self.ack_messages:
await self.message_acknowledgement(pulled_messages)
yield TriggerEvent({"status": "success", "message": pulled_messages})
return
else:
pulled_messages = await self.hook.pull(
project_id=self.project_id,
subscription=self.subscription,
max_messages=self.max_messages,
return_immediately=True,
)
self.log.info("Sleeping for %s seconds.", self.poke_interval)
await asyncio.sleep(self.poke_interval)
except Exception as e:
yield TriggerEvent({"status": "error", "message": str(e)})
return
[docs] async def message_acknowledgement(self, pulled_messages):
await self.hook.acknowledge(
project_id=self.project_id,
subscription=self.subscription,
messages=pulled_messages,
)
self.log.info("Acknowledged ack_ids from subscription %s", self.subscription)