How to start a command on bash in the screen by python

Question

I use python 2.7 and Django 1.11.5.

I want to check that my process manage.py, running in screen. If check is false I want to start process manage.py.

I use three files: check.py, start_screen.sh, start_server.sh.

I check the process in the first file(check.py):

import subprocess
from settings import BASE_DIR, SERVER

process_list = subprocess.check_output(['/bin/ps', 'ax'])
my_server = re.search('SCREEN .* server', process_list)
if my_server is None:
    s = subprocess.check_output(['/bin/bash', BASE_DIR + '/start_screen.sh'])

I start the screen in the second file(start_screen.sh) :

#!/usr/bin/env bash
screen -dmS server /bin/bash /home/user/Desktop/python_server/start_server.sh

I start the server in the third file(start_server.sh):

#!/bin/bash
cd /home/user/Desktop/python_server/
/usr/bin/python manage.py server 0.0.0.0:8000

I want to reduce the number of files to one python file.

Also I want to pass parameters like SERVER.PORT, SERVER.ADDRESS and BASE_DIR to the request.

Can anybody help with this?

Can you please explain what you want to obtain? From what I see I suspect that this is a script to start / stop Django but it doesn't seem something that you would like using for production. — Pitto
– Pitto, Commented Aug 13, 2019 at 12:49
I want to restart process in screen when(if) it falls. If you know other way to do this, it may be interesting for me. I want to make current code better and more pythonic. — Dmitrii Sidenko
– Dmitrii Sidenko, Commented Aug 13, 2019 at 13:38
@ДмитрийСиденко can't you use something like if ! pgrep -f "screen.*start_server.sh"; then screen -dmS server /bin/bash /home/user/Desktop/python_shome/user/Desktop/python_server/start_server.sh; fi? This way you don't have to invoke python script. — JUSHJUSH
– JUSHJUSH, Commented Aug 13, 2019 at 14:14
I have a variables like SERVER.PORT, SERVER.ADDRESS and BASE_DIR. I can get it only from my python script, so the best way is to call it from python as far as I see. In addition, I need to run multiple server instances and I need to change this variables in this script. But I am open to the opinions of others. — Dmitrii Sidenko
– Dmitrii Sidenko, Commented Aug 13, 2019 at 14:24
Sure thing... There are countless tutorials on the topic, I just link one here, I'd go - personal preference - with the Gunicorn part: developer.mozilla.org/en-US/docs/Learn/Server-side/Django/… — Pitto
– Pitto, Commented Aug 13, 2019 at 14:31

Dmitrii Sidenko · Accepted Answer · 2019-08-14 09:25:59Z

1

I thank the participant Pitto for help in improving the server.

I find the next way to solve the current problem.

import subprocess
from settings import BASE_DIR, PYTHON_DIR, SERVER_PORT

process_list = subprocess.check_output(['/bin/ps', 'ax'])
my_server = re.search('SCREEN .* server', process_list)
if my_server is None:
    s = subprocess.check_output([
        "screen -dmS server && "
        "screen -S server -X -p 0 stuff 'cd {0}/\n' && "
        "screen -S server -X -p 0 stuff '{1} manage.py runserver 0.0.0.0:{2}\n'"
        .format(BASE_DIR, PYTHON_DIR, SERVER_PORT)], shell=True)

If you want to start this screen from root you need to start python from root or make crontab with root. To configure crontab use:

crontab -e

answered Aug 14, 2019 at 9:25

Dmitrii Sidenko

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