Source code for

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import os
import pathlib
import sys
from typing import Optional

if sys.version_info >= (3, 8):
    from functools import cached_property
    from cached_property 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 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)

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