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I have a web-server that is based on flask+tornado combination. It works inside of a virtual environment (set up with python virtualenv).

I want the server to launch automatically on start up, from a regular user. What i have done to achieve this:

1) i have written a startup script with following contents:

cd /home/ubuntu/myserver
# enter virtualenv
source venv/bin/activate
# launch
python app.py > serverlog.log 2&>1 &

2) i have set up a crontab with crontab -e as:

SHELL=/bin/bash
@reboot /home/ubuntu/start_service.sh

When i execute startup script from the command line, everything is correctly launched. But after reboot in serverlog.log i see a stacktrace that tells of failure to bind to port 5000. what can i do to fix it?

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Crontab is not smart enough to keep your server up. When it goes down, it has to wait till crontab runs again; your clients will get a 404 error from your faulty server.

I advise you to use something like Supervisor. You can install it using easy_install like

   easy_install supervisor

You will need to deal with Supervisord and Supervisorctl. The first is a demon process manager that will run and make sure the PID from your

python app.py > serverlog.log 2&>1 &

keep running no matter what. You will be able to do such thing by creating a so called program on the supervisord.conf like

[program:flasktornado]
command=python app.py > serverlog.log 2&>1 &

Supervisorctl is how you control [ start | stop | restart ] the program you have just created on the supervisord configuration file. This might help you.

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