How to make Python script run as service?

Question

I want to run a python script in a CENTOS server:

#!/usr/bin/env python import socket try:         import thread  except ImportError:     import _thread as thread #Py3K changed it. class Polserv(object):     def __init__(self):         self.numthreads = 0         self.tidcount   = 0         self.port       = 843         self.sock       = socket.socket(socket.AF_INET, socket.SOCK_STREAM)         self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)         self.sock.bind(('100.100.100.100', self.port))         self.sock.listen(5)     def run(self):         while True:             thread.start_new_thread(self.handle, self.sock.accept())      def handle(self,conn,addr):         self.numthreads += 1         self.tidcount   += 1         tid=self.tidcount         while True:             data=conn.recv(2048)             if not data:                 conn.close()                 self.numthreads-=1                 break             #if "<policy-file-request/>\0" in data:             conn.sendall(b"<?xml version='1.0'?><cross-domain-policy><allow-access-from domain='*' to-ports='*'/></cross-domain-policy>")             conn.close()             self.numthreads-=1             break         #conn.sendall(b"[#%d (%d running)] %s" % (tid,self.numthreads,data) ) Polserv().run() 

Im using $ python flashpolicyd.py and it works fine... The question is: How to keep this script running even after I close the terminal(console)?

Answer 1

I use this code to daemonize my applications. It allows you start/stop/restart the script using the following commands.

python myscript.py start python myscript.py stop python myscript.py restart 

In addition to this I also have an init.d script for controlling my service. This allows you to automatically start the service when your operating system boots-up.

Here is a simple example to get your going. Simply move your code inside a class, and call it from the run function inside MyDeamon.

import sys import time  from daemon import Daemon   class YourCode(object):     def run(self):         while True:             time.sleep(1)   class MyDaemon(Daemon):     def run(self):         # Or simply merge your code with MyDaemon.         your_code = YourCode()         your_code.run()   if __name__ == "__main__":     daemon = MyDaemon('/tmp/daemon-example.pid')     if len(sys.argv) == 2:         if 'start' == sys.argv[1]:             daemon.start()         elif 'stop' == sys.argv[1]:             daemon.stop()         elif 'restart' == sys.argv[1]:             daemon.restart()         else:             print "Unknown command"             sys.exit(2)         sys.exit(0)     else:         print "usage: %s start|stop|restart" % sys.argv[0]         sys.exit(2) 

Upstart

If you are running an operating system that is using Upstart (e.g. CentOS 6) - you can also use Upstart to manage the service. If you use Upstart you can keep your script as is, and simply add something like this under /etc/init/my-service.conf

start on started sshd stop on runlevel [!2345]  exec /usr/bin/python /opt/my_service.py respawn 

You can then use start/stop/restart to manage your service.

e.g.

start my-service stop my-service restart my-service 

A more detailed example of working with upstart is available here.

Systemd

If you are running an operating system that uses Systemd (e.g. CentOS 7) you can take a look at the following Stackoverflow answer.

Answer 2

I offer two recommendations:

supervisord

1) Install the supervisor package (more verbose instructions here):

sudo apt-get install supervisor 

2) Create a config file for your daemon at /etc/supervisor/conf.d/flashpolicyd.conf:

[program:flashpolicyd] directory=/path/to/project/root environment=ENV_VARIABLE=example,OTHER_ENV_VARIABLE=example2 command=python flashpolicyd.py autostart=true autorestart=true 

3) Restart supervisor to load your new .conf

supervisorctl update supervisorctl restart flashpolicyd 

---

systemd (if currently used by your Linux distro)

[Unit] Description=My Python daemon  [Service] Type=simple ExecStart=/usr/bin/python3 /opt/project/main.py WorkingDirectory=/opt/project/ Environment=API_KEY=123456789 Environment=API_PASS=password Restart=always RestartSec=2  [Install] WantedBy=sysinit.target 

Place this file into /etc/systemd/system/my_daemon.service and enable it using systemctl daemon-reload && systemctl enable my_daemon && systemctl start my_daemon --no-block.

To view logs:

systemctl status my_daemon