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#
# http://www.apache.org/licenses/LICENSE-2.0
#
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from __future__ import annotations
from abc import abstractmethod
from typing import Any, AsyncIterator
from airflow.providers.amazon.aws.hooks.base_aws import AwsGenericHook
from airflow.providers.amazon.aws.utils.waiter_with_logging import async_wait
from airflow.triggers.base import BaseTrigger, TriggerEvent
[docs]class AwsBaseWaiterTrigger(BaseTrigger):
"""
Base class for all AWS Triggers that follow the "standard" model of just waiting on a waiter.
Subclasses need to implement the hook() method.
:param serialized_fields: Fields that are specific to the subclass trigger and need to be serialized
to be passed to the __init__ method on deserialization.
The conn id, region, and waiter delay & attempts are always serialized.
format: {<parameter_name>: <parameter_value>}
:param waiter_name: The name of the (possibly custom) boto waiter to use.
:param waiter_args: The arguments to pass to the waiter.
:param failure_message: The message to log if a failure state is reached.
:param status_message: The message logged when printing the status of the service.
:param status_queries: A list containing the JMESPath queries to retrieve status information from
the waiter response. See https://jmespath.org/tutorial.html
:param return_key: The key to use for the return_value in the TriggerEvent this emits on success.
Defaults to "value".
:param return_value: A value that'll be returned in the return_key field of the TriggerEvent.
Set to None if there is nothing to return.
:param waiter_delay: The amount of time in seconds to wait between attempts.
:param waiter_max_attempts: The maximum number of attempts to be made.
:param aws_conn_id: The Airflow connection used for AWS credentials. To be used to build the hook.
:param region_name: The AWS region where the resources to watch are. To be used to build the hook.
"""
def __init__(
self,
*,
serialized_fields: dict[str, Any],
waiter_name: str,
waiter_args: dict[str, Any],
failure_message: str,
status_message: str,
status_queries: list[str],
return_key: str = "value",
return_value: Any,
waiter_delay: int,
waiter_max_attempts: int,
aws_conn_id: str | None,
region_name: str | None = None,
):
# parameters that should be hardcoded in the child's implem
self.serialized_fields = serialized_fields
self.waiter_name = waiter_name
self.waiter_args = waiter_args
self.failure_message = failure_message
self.status_message = status_message
self.status_queries = status_queries
self.return_key = return_key
self.return_value = return_value
# parameters that should be passed directly from the child's parameters
self.waiter_delay = waiter_delay
self.attempts = waiter_max_attempts
self.aws_conn_id = aws_conn_id
self.region_name = region_name
[docs] def serialize(self) -> tuple[str, dict[str, Any]]:
# here we put together the "common" params,
# and whatever extras we got from the subclass in serialized_fields
params = dict(
{
"waiter_delay": self.waiter_delay,
"waiter_max_attempts": self.attempts,
"aws_conn_id": self.aws_conn_id,
},
**self.serialized_fields,
)
if self.region_name:
# if we serialize the None value from this, it breaks subclasses that don't have it in their ctor.
params["region_name"] = self.region_name
return (
# remember that self is an instance of the subclass here, not of this class.
self.__class__.__module__ + "." + self.__class__.__qualname__,
params,
)
@abstractmethod
[docs] def hook(self) -> AwsGenericHook:
"""Override in subclasses to return the right hook."""
...
[docs] async def run(self) -> AsyncIterator[TriggerEvent]:
hook = self.hook()
async with hook.async_conn as client:
waiter = hook.get_waiter(self.waiter_name, deferrable=True, client=client)
await async_wait(
waiter,
self.waiter_delay,
self.attempts,
self.waiter_args,
self.failure_message,
self.status_message,
self.status_queries,
)
yield TriggerEvent({"status": "success", self.return_key: self.return_value})
