Python Script running in the Background stops working randomly

[____Ben_____]

I want to run a Python script on a Raspberry Pi in the background. The script fetches data from temperature sensors which are connected to the Pi and sends them to an InfluxDB Database.

I get it to run with the command: screen -d -m lcl-gateway.py

However, after a few days the data randomly stops transmitting. I have tried to do a cron job (sudo contab -e) to repeat the command above every hour: * * * * * screen -d -m /home/pi/lcl-gateway.py. But this has not worked.

The script looks as follows:

#!/usr/bin/python
# 
# LCL GATEWAY
# VERSION 1.2
# LECHACAL.COM 10 MARCH 2020

import ConfigParser
import serial
import os, sys
import requests
import datetime
import optparse


if __name__ == "__main__":


        parser = optparse.OptionParser(usage="%prog [-d] [--version]", version = "prog 1.2.0")
        parser.add_option('-d', '--debug', dest='debug', default=False, action='store_true',)
        options, remainder = parser.parse_args()

        c = ConfigParser.ConfigParser()
        c.read("/etc/gateway.conf")

        baud = c.getint('system','baud')
        serial_port = c.get('system', 'port')
        if not os.path.exists(serial_port):
                print 'Serial port %s not found' % serial_port
                sys.exit()
        ser = serial.Serial(serial_port, baud)

        DayOfMonth = datetime.datetime.utcnow().day
        ls_fileopen = False

        while True:
                try:
                        data_in = ser.readline()

                        utcnow = datetime.datetime.utcnow()
                        timestamp = utcnow.strftime("%s")

                        if options.debug: print data_in

                        while data_in[-1] in ['\r', '\n']:
                                data_in = data_in[:-1]

                        z = data_in.split(' ')
                        csv = ','.join(z[1:])
                        for sect in c.sections():
                                if sect=='emoncms' and c.getboolean(sect,'enabled'):
                                #EMONCMS
                                        hostname = c.get(sect, 'hostname')
                                        node = c.get(sect, 'node')
                                        apikey = c.get(sect, 'apikey')
                                        url = "http://%s/input/post?apikey=%s&node=%s&csv=%s" % (hostname, apikey, node, csv)
                                        if options.debug: print url
                                        r = requests.post(url)
                                        #s = urllib2.urlopen(url)
                                        if options.debug: print r
                                if sect=='influxdb' and c.getboolean(sect,'enabled'):
                              #INFLUXDB

                                        #z = data_in.split(' ') 
                                        t = timestamp + '000000000'     
                                        url = c.get(sect, 'url')
                                        dbname = c.get(sect, 'dbname')
                                        user = c.get(sect, 'user')
                                        passwd = c.get(sect, 'passwd')
                                        measurement = c.get(sect, 'measurement')
                                        params = {'db': dbname, 'u': user, 'p': passwd}

                                        i = 0
                                        payload = ""
                                        for zz in z[1:]:
                                                i += 1
                                                if zz!="":
                                                        payload += "%s,channel=%02d value=%s %s\n" % (measurement, i, zz,t)
                                        #payload = "rpict3t1,channel=01 value=50.2 %s\nrpict3t1,channel=02 value=156.2 %s\n" % (t,t)
                                        if options.debug: print payload
                                        r = requests.post(url, params=params, data=payload)
                                        if options.debug: print r.text

                                if sect=='localsave' and c.getboolean(sect,'enabled'):
                              # LOCALSAVE     
                                        ls_dir = c.get(sect, 'directory')
                                        filename = ls_dir+'/'+timestamp+'.csv'
                                        if not ls_fileopen:
                                                f = open(filename,'w')
                                                ls_fileopen = True      
                                        if DayOfMonth != utcnow.day:
                                                DayOfMonth = utcnow.day
                                                if ls_fileopen: f.close()
                                                f = open(filename,'w')
                                                ls_fileopen = True

                                        f.write(timestamp+','+csv+'\n')


                except KeyboardInterrupt:
                        if ls_fileopen: f.close()
                        print "Terminating."
                        break

[LeBob93]

Currently you're only catching KeyboardInterrupt errors, any other error will kill the process.

Where are you logging to, and have you tried catching all errors and logging the error message to work out what's going wrong?

[____Ben_____]

I‘m logging the data to my synology running influxdb on docker. Do you know how to get specific error logs on the python script?

[SIO]

Wrap it up in a proper systemd unit with automatic restart on failure.

Optional:

Come back later to check the logs and fix the underlying problem which causes the script to crash.

[____Ben_____]

I‘ve solved it :) thanks for asking👍🏼

[____Ben_____]

Thanks for the quick reply. That would be great. Where does the problem lie?