baseimage-tutorial-framework/lib/tfw/builtins/log_monitoring_event_handler.py

67 lines
2.0 KiB
Python

import logging
from tfw.config import TFWENV
from tfw.networking import Scope
from tfw.components import LogInotifyObserver
from .event_handler import EventHandler
LOG = logging.getLogger(__name__)
class LogMonitoringEventHandler(EventHandler):
"""
Monitors the output of a supervisor process (stdout, stderr) and
sends the results to the frontend.
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.
"""
def __init__(self, key, process_name, log_tail=0):
super().__init__(key, scope=Scope.WEBSOCKET)
self.process_name = process_name
self._monitor = LogInotifyObserver(
server_connector=self.server_connector,
supervisor_uri=TFWENV.SUPERVISOR_HTTP_URI,
process_name=process_name,
log_tail=log_tail
)
self._monitor.start()
self.command_handlers = {
'process_name': self.handle_process_name,
'log_tail': self.handle_log_tail
}
def handle_event(self, message):
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):
"""
Changes the monitored process.
:param data: TFW message data containing 'value'
(name of the process to monitor)
"""
self._monitor.process_name = data['value']
def handle_log_tail(self, data):
"""
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).
:param data: TFW message data containing 'value'
(new tail length)
"""
self._monitor.log_tail = data['value']
def cleanup(self):
self._monitor.stop()