I am trying to define a program to receive an HTML request to trigger a process in my server and leave it running there, as a daemon, until another HTML call tells the server to kill it. My problem is leaving the daemon running after a proper HTML response.
I am using a Flask-based python web server. I have tried python's multiprocessing and subprocess modules to no success, typically the main process would finish and kill the subprocess before it could do any good.
In my latest iteration I've tried to combine both, using a multripocessing thread as daemon to start a subprocess but in this case the server never returns a response - although the thread is daemonised, it is waiting for the subprocess to finish (which it never will) and holding the main program from returning...
I am out of ideas... help please?
This is the code:
from flask import Flask, request, abort
app = Flask(__name__)
import sys, time
def f():
import subprocess as sub
p = sub.Popen(['/path/to/file.py'])
print "process created " + str(p.pid) # prints to log
@app.route("/", methods = ['POST', 'GET'])
def home():
if request.method == "GET":
# return an HTML form with a 'Login' button
return """
<!DOCTYPE html>
<html>
<head>
</head>
<body>
Testing Login
<form action = "/" method = "post">
<input type="submit" value="Login">
</form>
</body>
</html>
"""
elif request.method == "POST":
import sys
import multiprocessing as mp
try:
m = mp.Process(name = 'sub', target = f)
m.daemon = True
m.start()
time.sleep(1) # artifically wait 1 sec for m to trigger subprocess
return "Logged in!"
except:
return "error! <br> " + str(sys.exc_info())
else:
abort(401)
