pvc/node-daemon/pvcnoded/VMConsoleWatcherInstance.py

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#!/usr/bin/env python3
# VMConsoleWatcherInstance.py - Class implementing a console log watcher for PVC domains
# Part of the Parallel Virtual Cluster (PVC) system
#
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# Copyright (C) 2018-2020 Joshua M. Boniface <joshua@boniface.me>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>.
#
###############################################################################
import os
import time
from threading import Thread, Event
from collections import deque
import pvcnoded.zkhandler as zkhandler
class VMConsoleWatcherInstance(object):
# Initialization function
def __init__(self, domuuid, domname, zk_conn, config, logger, this_node):
self.domuuid = domuuid
self.domname = domname
self.zk_conn = zk_conn
self.config = config
self.logfile = '{}/{}.log'.format(config['console_log_directory'], self.domname)
self.console_log_lines = config['console_log_lines']
self.logger = logger
self.this_node = this_node
# Try to append (create) the logfile and set its permissions
open(self.logfile, 'a').close()
os.chmod(self.logfile, 0o600)
self.logdeque = deque(open(self.logfile), self.console_log_lines)
self.stamp = None
self.cached_stamp = None
# Set up the deque with the current contents of the log
self.last_loglines = None
self.loglines = None
# Thread options
self.thread = None
self.thread_stopper = Event()
# Start execution thread
def start(self):
self.thread_stopper.clear()
self.thread = Thread(target=self.run, args=(), kwargs={})
self.logger.out('Starting VM log parser', state='i', prefix='Domain {}:'.format(self.domuuid))
self.thread.start()
# Stop execution thread
def stop(self):
if self.thread and self.thread.isAlive():
self.logger.out('Stopping VM log parser', state='i', prefix='Domain {}:'.format(self.domuuid))
self.thread_stopper.set()
# Do one final flush
self.update()
# Main entrypoint
def run(self):
# Main loop
while not self.thread_stopper.is_set():
self.update()
time.sleep(0.5)
def update(self):
self.stamp = os.stat(self.logfile).st_mtime
if self.stamp != self.cached_stamp:
self.cached_stamp = self.stamp
self.fetch_lines()
# Update Zookeeper with the new loglines if they changed
if self.loglines != self.last_loglines:
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zkhandler.writedata(self.zk_conn, {'/domains/{}/consolelog'.format(self.domuuid): self.loglines})
self.last_loglines = self.loglines
def fetch_lines(self):
self.logdeque = deque(open(self.logfile), self.console_log_lines)
self.loglines = ''.join(self.logdeque)