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"""
This module contains a hook (AwsLogsHook) with some very basic
functionality for interacting with AWS CloudWatch.
"""
from airflow.contrib.hooks.aws_hook import AwsHook
[docs]class AwsLogsHook(AwsHook):
"""
Interact with AWS CloudWatch Logs
:param region_name: AWS Region Name (example: us-west-2)
:type region_name: str
"""
def __init__(self, region_name=None, *args, **kwargs):
self.region_name = region_name
super(AwsLogsHook, self).__init__(*args, **kwargs)
[docs] def get_conn(self):
"""
Establish an AWS connection for retrieving logs.
:rtype: CloudWatchLogs.Client
"""
return self.get_client_type('logs', region_name=self.region_name)
[docs] def get_log_events(self, log_group, log_stream_name, start_time=0, skip=0, start_from_head=True):
"""
A generator for log items in a single stream. This will yield all the
items that are available at the current moment.
:param log_group: The name of the log group.
:type log_group: str
:param log_stream_name: The name of the specific stream.
:type log_stream_name: str
:param start_time: The time stamp value to start reading the logs from (default: 0).
:type start_time: int
: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.
:type skip: int
:param start_from_head: whether to start from the beginning (True) of the log or
at the end of the log (False).
:type start_from_head: bool
:rtype: dict
: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.
"""
next_token = None
event_count = 1
while event_count > 0:
if next_token is not None:
token_arg = {'nextToken': next_token}
else:
token_arg = {}
response = self.get_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 = skip - event_count
events = []
for ev in events:
yield ev
if 'nextForwardToken' in response:
next_token = response['nextForwardToken']
else:
return