#
# Licensed to the Apache Software Foundation (ASF) under one
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# 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.
import os
import pathlib
from typing import Optional
from airflow.compat.functools import cached_property
from airflow.configuration import conf
from airflow.utils.log.file_task_handler import FileTaskHandler
from airflow.utils.log.logging_mixin import LoggingMixin
[docs]class S3TaskHandler(FileTaskHandler, LoggingMixin):
"""
S3TaskHandler is a python log handler that handles and reads
task instance logs. It extends airflow FileTaskHandler and
uploads to and reads from S3 remote storage.
"""
def __init__(self, base_log_folder: str, s3_log_folder: str, filename_template: Optional[str] = None):
super().__init__(base_log_folder, filename_template)
self.remote_base = s3_log_folder
self.log_relative_path = ''
self._hook = None
self.closed = False
self.upload_on_close = True
@cached_property
[docs] def hook(self):
"""Returns S3Hook."""
remote_conn_id = conf.get('logging', 'REMOTE_LOG_CONN_ID')
try:
from airflow.providers.amazon.aws.hooks.s3 import S3Hook
return S3Hook(remote_conn_id, transfer_config_args={"use_threads": False})
except Exception as e:
self.log.exception(
'Could not create an S3Hook with connection id "%s". '
'Please make sure that apache-airflow[aws] is installed and '
'the S3 connection exists. Exception : "%s"',
remote_conn_id,
e,
)
return None
[docs] def set_context(self, ti):
super().set_context(ti)
# Local location and remote location is needed to open and
# upload local log file to S3 remote storage.
self.log_relative_path = self._render_filename(ti, ti.try_number)
self.upload_on_close = not ti.raw
# Clear the file first so that duplicate data is not uploaded
# when re-using the same path (e.g. with rescheduled sensors)
if self.upload_on_close:
with open(self.handler.baseFilename, 'w'):
pass
[docs] def close(self):
"""Close and upload local log file to remote storage S3."""
# When application exit, system shuts down all handlers by
# calling close method. Here we check if logger is already
# closed to prevent uploading the log to remote storage multiple
# times when `logging.shutdown` is called.
if self.closed:
return
super().close()
if not self.upload_on_close:
return
local_loc = os.path.join(self.local_base, self.log_relative_path)
remote_loc = os.path.join(self.remote_base, self.log_relative_path)
if os.path.exists(local_loc):
# read log and remove old logs to get just the latest additions
log = pathlib.Path(local_loc).read_text()
self.s3_write(log, remote_loc)
# Mark closed so we don't double write if close is called twice
self.closed = True
def _read(self, ti, try_number, metadata=None):
"""
Read logs of given task instance and try_number from S3 remote storage.
If failed, read the log from task instance host machine.
:param ti: task instance object
:param try_number: task instance try_number to read logs from
:param metadata: log metadata,
can be used for steaming log reading and auto-tailing.
"""
# Explicitly getting log relative path is necessary as the given
# task instance might be different than task instance passed in
# in set_context method.
log_relative_path = self._render_filename(ti, try_number)
remote_loc = os.path.join(self.remote_base, log_relative_path)
log_exists = False
log = ""
try:
log_exists = self.s3_log_exists(remote_loc)
except Exception as error:
self.log.exception("Failed to verify remote log exists %s.", remote_loc)
log = f'*** Failed to verify remote log exists {remote_loc}.\n{error}\n'
if log_exists:
# If S3 remote file exists, we do not fetch logs from task instance
# local machine even if there are errors reading remote logs, as
# returned remote_log will contain error messages.
remote_log = self.s3_read(remote_loc, return_error=True)
log = f'*** Reading remote log from {remote_loc}.\n{remote_log}\n'
return log, {'end_of_log': True}
else:
log += '*** Falling back to local log\n'
local_log, metadata = super()._read(ti, try_number)
return log + local_log, metadata
[docs] def s3_log_exists(self, remote_log_location: str) -> bool:
"""
Check if remote_log_location exists in remote storage
:param remote_log_location: log's location in remote storage
:return: True if location exists else False
"""
return self.hook.check_for_key(remote_log_location)
[docs] def s3_read(self, remote_log_location: str, return_error: bool = False) -> str:
"""
Returns the log found at the remote_log_location. Returns '' if no
logs are found or there is an error.
:param remote_log_location: the log's location in remote storage
:param return_error: if True, returns a string error message if an
error occurs. Otherwise returns '' when an error occurs.
:return: the log found at the remote_log_location
"""
try:
return self.hook.read_key(remote_log_location)
except Exception as error:
msg = f'Could not read logs from {remote_log_location} with error: {error}'
self.log.exception(msg)
# return error if needed
if return_error:
return msg
return ''
[docs] def s3_write(self, log: str, remote_log_location: str, append: bool = True, max_retry: int = 1):
"""
Writes the log to the remote_log_location. Fails silently if no hook
was created.
:param log: the log to write to the remote_log_location
:param remote_log_location: the log's location in remote storage
:param append: if False, any existing log file is overwritten. If True,
the new log is appended to any existing logs.
:param max_retry: Maximum number of times to retry on upload failure
"""
try:
if append and self.s3_log_exists(remote_log_location):
old_log = self.s3_read(remote_log_location)
log = '\n'.join([old_log, log]) if old_log else log
except Exception:
self.log.exception('Could not verify previous log to append')
# Default to a single retry attempt because s3 upload failures are
# rare but occasionally occur. Multiple retry attempts are unlikely
# to help as they usually indicate non-empheral errors.
for try_num in range(1 + max_retry):
try:
self.hook.load_string(
log,
key=remote_log_location,
replace=True,
encrypt=conf.getboolean('logging', 'ENCRYPT_S3_LOGS'),
)
break
except Exception:
if try_num < max_retry:
self.log.warning('Failed attempt to write logs to %s, will retry', remote_log_location)
else:
self.log.exception('Could not write logs to %s', remote_log_location)
