Touch reload event listner for Supervisor

touch_reload_event_listener.py

#!/usr/bin/env python2
# -*- coding: utf-8 -*-

from __future__ import (print_function, unicode_literals,
                        absolute_import, generators, division)

# The MIT License (MIT)
# Copyright (c) 2016 ymt2 (Tatsuya Yamamoto)
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the "Software"),
# to deal in the Software without restriction, including without limitation
# the rights to use, copy, modify, merge, publish, distribute, sublicense,
# and/or sell copies of the Software, and to permit persons to whom the Software
# is furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
# INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
# PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
# FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT
# OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
# OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

# A supervisor config snippet that tells supervisor to use this script
# as a listener is below.
#
# [eventlistener:touch_reload]
# command=python touch_reload_event_listener.py -p proc -f /home/user/reload.trigger
# events=PROCESS_STATE

doc = """\
python2 {} [-p processname] [-f trigger_file_name]
"""
doc = doc.format(__file__)

import os
import sys
import time

from watchdog.events import FileSystemEventHandler
from watchdog.observers import Observer

from supervisor import childutils
from superlance.compat import xmlrpclib


class TouchReload():
    def __init__(self, process, trigger_file_path, rpc=None):
        self.process = process
        self.trigger_file_path = trigger_file_path
        self.rpc = rpc

    def runforever(self):
        monitor_path = os.path.abspath(os.path.dirname(self.trigger_file_path))

        event_handler = ModifyHandler(self.process,
                                      self.trigger_file_path,
                                      self.restart)
        observer = Observer()
        observer.schedule(event_handler, monitor_path, recursive=False)
        observer.start()

        try:
            while True:
                time.sleep(1)
        except KeyboardInterrupt:
            observer.stop()
            observer.join()

    def restart(self, name):
        try:
            self.rpc.supervisor.stopProcess(name)
        except xmlrpclib.Fault as e:
            self.stderr.write(e)

            raise

        try:
            self.rpc.supervisor.startProcess(name)
        except xmlrpclib.Fault as e:
            self.stderr.write(e)

            raise


class ModifyHandler(FileSystemEventHandler):
    def __init__(self, process, trigger_file_path, callback):
        self.process = process
        self.trigger_file_path = trigger_file_path
        self.callback = callback

    def on_modified(self, event):
        if event.is_directory:
            return

        if event.src_path == self.trigger_file_path:
            self.callback(self.process)


def usage():
    print(doc)
    sys.exit(255)


def touch_reload_from_args(arguments):
    import getopt

    short_args = "p:f:"

    if not arguments:
        return None

    try:
        opts, args = getopt.getopt(arguments, short_args)
    except:
        return None

    process = None
    trigger_file = None

    for option, value in opts:
        if option in ('-p'):
            process = value

        if option in ('-f'):
            trigger_file = value

    if process is None or trigger_file is None:
        return None

    touch_reload = TouchReload(process, trigger_file)

    return touch_reload


def main():
    touch_reload = touch_reload_from_args(sys.argv[1:])

    if touch_reload is None:
        usage()

    touch_reload.rpc = childutils.getRPCInterface(os.environ)
    touch_reload.runforever()


if __name__ == '__main__':
    main()