Source code for airflow.providers.amazon.aws.hooks.logs
#
# 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 a hook (AwsLogsHook) with some very basic
functionality for interacting with AWS CloudWatch.
"""
from __future__ import annotations
from typing import Generator
from airflow.providers.amazon.aws.hooks.base_aws import AwsBaseHook
# Guidance received from the AWS team regarding the correct way to check for the end of a stream is that the
# value of the nextForwardToken is the same in subsequent calls.
# The issue with this approach is, it can take a huge amount of time (e.g. 20 seconds) to retrieve logs using
# this approach. As an intermediate solution, we decided to stop fetching logs if 3 consecutive responses
# are empty.
# See PR https://github.com/apache/airflow/pull/20814
[docs]NUM_CONSECUTIVE_EMPTY_RESPONSE_EXIT_THRESHOLD = 3
[docs]class AwsLogsHook(AwsBaseHook):
"""
Interact with Amazon CloudWatch Logs.
Provide thin wrapper around :external+boto3:py:class:`boto3.client("logs") <CloudWatchLogs.Client>`.
Additional arguments (such as ``aws_conn_id``) may be specified and
are passed down to the underlying AwsBaseHook.
.. seealso::
- :class:`airflow.providers.amazon.aws.hooks.base_aws.AwsBaseHook`
"""
def __init__(self, *args, **kwargs) -> None:
kwargs["client_type"] = "logs"
super().__init__(*args, **kwargs)
[docs] def get_log_events(
self,
log_group: str,
log_stream_name: str,
start_time: int = 0,
skip: int = 0,
start_from_head: bool = True,
) -> Generator:
"""
A generator for log items in a single stream. This will yield all the
items that are available at the current moment.
.. seealso::
- :external+boto3:py:meth:`CloudWatchLogs.Client.get_log_events`
:param log_group: The name of the log group.
:param log_stream_name: The name of the specific stream.
:param start_time: The time stamp value to start reading the logs from (default: 0).
:param skip: The number of log entries to skip at the start (default: 0).
This is for when there are multiple entries at the same timestamp.
:param start_from_head: whether to start from the beginning (True) of the log or
at the end of the log (False).
:return: | A CloudWatch log event with the following key-value pairs:
| 'timestamp' (int): The time in milliseconds of the event.
| 'message' (str): The log event data.
| 'ingestionTime' (int): The time in milliseconds the event was ingested.
"""
num_consecutive_empty_response = 0
next_token = None
while True:
if next_token is not None:
token_arg: dict[str, str] = {"nextToken": next_token}
else:
token_arg = {}
response = self.conn.get_log_events(
logGroupName=log_group,
logStreamName=log_stream_name,
startTime=start_time,
startFromHead=start_from_head,
**token_arg,
)
events = response["events"]
event_count = len(events)
if event_count > skip:
events = events[skip:]
skip = 0
else:
skip -= event_count
events = []
yield from events
if not event_count:
num_consecutive_empty_response += 1
if num_consecutive_empty_response >= NUM_CONSECUTIVE_EMPTY_RESPONSE_EXIT_THRESHOLD:
# Exit if there are more than NUM_CONSECUTIVE_EMPTY_RESPONSE_EXIT_THRESHOLD consecutive
# empty responses
return
elif next_token != response["nextForwardToken"]:
num_consecutive_empty_response = 0
else:
# Exit if the value of nextForwardToken is same in subsequent calls
return
next_token = response["nextForwardToken"]
