Upstart code to daemonize quickly a set of instructions (place them on /etc/init/filename.conf where filename will be the name of the service to be executed, like "service filename start")

filename.conf

#!upstart

description "Place a description here"
author "John Doe"

start on (net-device-up
            and local-filesystems
            and runlevel [2345])
stop on runlevel [06]

respawn

script
    # place here all instructions below this line, like "python -m file.py" (without the quotes)
end script