Script for programmatically checking weather a daemonocle daemon is up or down

daemonocle_status_check.py

# Script for programmatically checking weather a daemonocle daemon is up or down
# -> see: https://github.com/jnrbsn/daemonocle
# -> works around the following issue: https://github.com/jnrbsn/daemonocle/issues/18
# -> requires knowledge of the location of the daemon's pid file
# -> tested with CPython 3.6
# Licenced under the MIT License (MIT)
# Copyright (c) 2017 @s-m-e


import os
import psutil # non-standard-library dependency: pip install psutil


class no_pid_error(Exception):
	pass


def is_daemon_up(pid_file_path):
	
	try:
		_ = __get_daemon_pid__(pid_file_path)
		return True
	except no_pid_error:
		return False


def __get_daemon_pid__(pid_file_path):
	
	try:
		f = open(pid_file_path, 'r')
		pid_data = f.read()
		f.close()
	except FileNotFoundError:
		raise no_pid_error()
		
	try:
		pid = int(pid_data)
	except ValueError:
		raise no_pid_error()
		
	if pid is not None and psutil.pid_exists(pid):
		return pid
	else:
		os.remove(pid_file_path) # daemonocle does that but you might as well want to skip it
		raise no_pid_error()