baseimage-tutorial-framework/tfw/components/process_management/process_log_handler.py

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import logging
from .log_inotify_observer import LogInotifyObserver
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LOG = logging.getLogger(__name__)
class ProcessLogHandler:
keys = ['logmonitor']
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"""
Monitors the output of a supervisor process (stdout, stderr) and
sends the results to the frontend.
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Accepts messages that have a data['command'] key specifying
a command to be executed.
The API of each command is documented in their respective handler.
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"""
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def __init__(self, *, process_name, supervisor_uri, log_tail=0):
self.server_connector = None
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self.process_name = process_name
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self._supervisor_uri = supervisor_uri
self._initial_log_tail = log_tail
self._monitor = None
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self.command_handlers = {
'process_name': self.handle_process_name,
'log_tail': self.handle_log_tail
}
def start(self):
self._monitor = LogInotifyObserver(
server_connector=self.server_connector,
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supervisor_uri=self._supervisor_uri,
process_name=self.process_name,
log_tail=self._initial_log_tail
)
self._monitor.start()
def handle_event(self, message, _):
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try:
data = message['data']
self.command_handlers[data['command']](data)
except KeyError:
LOG.error('IGNORING MESSAGE: Invalid message received: %s', message)
def handle_process_name(self, data):
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"""
Changes the monitored process.
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:param data: TFW message data containing 'value'
(name of the process to monitor)
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"""
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self._monitor.process_name = data['value']
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def handle_log_tail(self, data):
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"""
Sets tail length of the log the monitor will send
to the frontend (the monitor will send back the last
'value' characters of the log).
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:param data: TFW message data containing 'value'
(new tail length)
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"""
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self._monitor.log_tail = data['value']
def cleanup(self):
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self._monitor.stop()