#
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
"""This module contains SFTP sensor."""
from __future__ import annotations
import os
from datetime import datetime, timedelta
from typing import TYPE_CHECKING, Any, Callable, Sequence
from paramiko.sftp import SFTP_NO_SUCH_FILE
from airflow.configuration import conf
from airflow.exceptions import AirflowException
from airflow.providers.sftp.hooks.sftp import SFTPHook
from airflow.providers.sftp.triggers.sftp import SFTPTrigger
from airflow.sensors.base import BaseSensorOperator, PokeReturnValue
from airflow.utils.timezone import convert_to_utc, parse
if TYPE_CHECKING:
from airflow.utils.context import Context
[docs]class SFTPSensor(BaseSensorOperator):
"""
Waits for a file or directory to be present on SFTP.
:param path: Remote file or directory path
:param file_pattern: The pattern that will be used to match the file (fnmatch format)
:param sftp_conn_id: The connection to run the sensor against
:param newer_than: DateTime for which the file or file path should be newer than, comparison is inclusive
:param deferrable: If waiting for completion, whether to defer the task until done, default is ``False``.
"""
[docs] template_fields: Sequence[str] = (
"path",
"newer_than",
)
def __init__(
self,
*,
path: str,
file_pattern: str = "",
newer_than: datetime | str | None = None,
sftp_conn_id: str = "sftp_default",
python_callable: Callable | None = None,
op_args: list | None = None,
op_kwargs: dict[str, Any] | None = None,
deferrable: bool = conf.getboolean("operators", "default_deferrable", fallback=False),
**kwargs,
) -> None:
super().__init__(**kwargs)
self.path = path
self.file_pattern = file_pattern
self.hook: SFTPHook | None = None
self.sftp_conn_id = sftp_conn_id
self.newer_than: datetime | str | None = newer_than
self.python_callable: Callable | None = python_callable
self.op_args = op_args or []
self.op_kwargs = op_kwargs or {}
self.deferrable = deferrable
[docs] def poke(self, context: Context) -> PokeReturnValue | bool:
self.hook = SFTPHook(self.sftp_conn_id)
self.log.info("Poking for %s, with pattern %s", self.path, self.file_pattern)
files_found = []
if self.file_pattern:
files_from_pattern = self.hook.get_files_by_pattern(self.path, self.file_pattern)
if files_from_pattern:
actual_files_to_check = [
os.path.join(self.path, file_from_pattern) for file_from_pattern in files_from_pattern
]
else:
return False
else:
actual_files_to_check = [self.path]
for actual_file_to_check in actual_files_to_check:
try:
mod_time = self.hook.get_mod_time(actual_file_to_check)
self.log.info("Found File %s last modified: %s", actual_file_to_check, mod_time)
except OSError as e:
if e.errno != SFTP_NO_SUCH_FILE:
raise AirflowException from e
continue
if self.newer_than:
if isinstance(self.newer_than, str):
self.newer_than = parse(self.newer_than)
_mod_time = convert_to_utc(datetime.strptime(mod_time, "%Y%m%d%H%M%S"))
_newer_than = convert_to_utc(self.newer_than)
if _newer_than <= _mod_time:
files_found.append(actual_file_to_check)
self.log.info(
"File %s has modification time: '%s', which is newer than: '%s'",
actual_file_to_check,
str(_mod_time),
str(_newer_than),
)
else:
self.log.info(
"File %s has modification time: '%s', which is older than: '%s'",
actual_file_to_check,
str(_mod_time),
str(_newer_than),
)
else:
files_found.append(actual_file_to_check)
self.hook.close_conn()
if not len(files_found):
return False
if self.python_callable is not None:
if self.op_kwargs:
self.op_kwargs["files_found"] = files_found
callable_return = self.python_callable(*self.op_args, **self.op_kwargs)
return PokeReturnValue(
is_done=True,
xcom_value={"files_found": files_found, "decorator_return_value": callable_return},
)
return True
[docs] def execute(self, context: Context) -> Any:
# Unlike other async sensors, we do not follow the pattern of calling the synchronous self.poke()
# method before deferring here. This is due to the current limitations we have in the synchronous
# SFTPHook methods. They are as follows:
#
# For file_pattern sensing, the hook implements list_directory() method which returns a list of
# filenames only without the attributes like modified time which is required for the file_pattern
# sensing when newer_than is supplied. This leads to intermittent failures potentially due to
# throttling by the SFTP server as the hook makes multiple calls to the server to get the
# attributes for each of the files in the directory.This limitation is resolved here by instead
# calling the read_directory() method which returns a list of files along with their attributes
# in a single call. We can add back the call to self.poke() before deferring once the above
# limitations are resolved in the sync sensor.
if self.deferrable:
self.defer(
timeout=timedelta(seconds=self.timeout),
trigger=SFTPTrigger(
path=self.path,
file_pattern=self.file_pattern,
sftp_conn_id=self.sftp_conn_id,
poke_interval=self.poke_interval,
newer_than=self.newer_than,
),
method_name="execute_complete",
)
else:
return super().execute(context=context)
[docs] def execute_complete(self, context: dict[str, Any], event: Any = None) -> None:
"""
Execute callback when the trigger fires; returns immediately.
Relies on trigger to throw an exception, otherwise it assumes execution was
successful.
"""
if event is not None:
if "status" in event and event["status"] == "error":
raise AirflowException(event["message"])
if "status" in event and event["status"] == "success":
self.log.info("%s completed successfully.", self.task_id)
self.log.info(event["message"])
return None
raise AirflowException("No event received in trigger callback")