gdata.py

#!/usr/bin/env python3
import sys
import os
import json
import time
import argparse
import psutil

def is_running(pid_file):
	'''
	determine if the daemon is running.
	check for an exisiting pid file, check the pid. 
	if the pid is running return true, otherwise false.
	'''
	debug("Checking for running process")
	if os.path.exists(pid_file):
		debug("pid_file exists")
		with open(pid_file) as f:
			old_pid = int(f.read().strip())
		try:
			debug(f"Checking for pid {old_pid}")
			p = psutil.Process(old_pid)
			return True
		except psutil.NoSuchProcess:
			pass
	return False

def startup(pid_file):
	'''
	Check if daemon is running if not gork and exit else just exit
	'''
	if not get_debug():
		if is_running(pid_file):
			log(f'daemon already running')
			sys.exit(0)

		pid = os.fork()
		if pid > 0:
			sys.exit(0)

		with open(pid_file,"w") as f:
			print(os.getpid(),file=f)

		log(f'Daemon started, pid: {os.getpid()}')
	else:
		debug("Debug mode no daemon")

def log(*args):
	'''
	Write to logfile also debug if debug is enabled
	'''
	tfmt = '%m-%d-%Y %H:%M'
	with open("/tmp/get-data.log","a") as f:
		now = time.time()
		lt = time.localtime(now)
		tstr = time.strftime(tfmt,lt)
		print(f'{tstr}:',*args,file=f)
		debug(*args)

def get_config():
	'''
	read common config file 
	'''
	try:
		with open('sensors.json') as f:
			return  json.load(f)
	except:
		return None
def main(base_dir,pid_file):
	'''
	loop through defined sensors and write data to {base_dir}/{host}-{sensor}.json
	sleep for poll interval miliseconds
	'''
	config = None
	while not config:
		config = get_config()
		if not config:
			time.sleep(1)
	poll_interval = config['poll_interval']/1000
	while True:
		time.sleep(poll_interval)
		config = get_config()
		if not config:
			continue
		poll_interval = config['poll_interval']/1000
		for name,sensor in config['sensors'].items():
			if '::' in name:
				continue
			#if not sensor['active']:
			#	continue
			host = sensor['host']
			sen = sensor['sensor']
			server = config['server']
			debug(server,host,sensor)
			data_file = f'{base_dir}/{host}-{sen}.json'
			client = rest.RestClient(
				server=server,
				host=host,
				sensor=sen)
			try:
				sensor_data = client.read()
				if not 'error' in sensor_data:
					with open(data_file,'w') as f:
						debug("Writing",data_file)
						json.dump(sensor_data,f,indent=2)
			except Exception as e:
				with open('/tmp/get-data.log','a') as f:
					log(f'Exception getting data for {host}-{sen}: {e}')

if __name__ == "__main__":
	parser = argparse.ArgumentParser(
			prog=f"get-data",
			description="daemon to collect data via sensorfs",
			epilog="A SensorFS RestAPI Example. See https://github.com/nicciniamh/sensorfs"
		)
	parser.add_argument('-d','--debug',action='store_true',default=False,help='turn on copious debugging messages')
	parser.add_argument('-rp','--run-path',type=str,default=None,help='run program in path',metavar="path")
	args = parser.parse_args()
	prog_dir = os.path.dirname(os.path.realpath(sys.argv[0]))
	if args.run_path:
		prog_dir = args.run_path
	os.chdir(prog_dir)
	sys.path.append(os.path.expanduser('~/lib'))
	sys.path.append(prog_dir)

	from dflib import rest
	from dflib.debug import *
	
	pid_file = '/tmp/get-data.pid'
	data_path = '/Volumes/RamDisk/sensordata'

	set_debug(args.debug)
	try:
		startup(pid_file)
		main(data_path,pid_file)
	except KeyboardInterrupt:
		pass
	except Exception as e:
		log(f'Exception: {e}')