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Running uWSGI via Upstart

Upstart is the init system of Ubuntu-like distributions.

It is based on declarative configuration files -- not shell scripts of yore -- that are put in the :file:`/etc/init` directory.

A simple script (/etc/init/uwsgi.conf)

# simple uWSGI script

description "uwsgi tiny instance"
start on runlevel [2345]
stop on runlevel [06]

respawn

exec uwsgi --master --processes 4 --die-on-term --socket :3031 --wsgi-file /var/www/myapp.wsgi

Using the Emperor

A better approach than init files for each app would be to only start an Emperor via Upstart and let it deal with the rest.

# Emperor uWSGI script

description "uWSGI Emperor"
start on runlevel [2345]
stop on runlevel [06]

respawn

exec uwsgi --emperor /etc/uwsgi

If you want to run the Emperor under the master process (for accessing advanced features) remember to add --die-on-term

# Emperor uWSGI script

description "uWSGI Emperor"
start on runlevel [2345]
stop on runlevel [06]

respawn

exec uwsgi --master --die-on-term --emperor /etc/uwsgi

What is --die-on-term?

By default uWSGI maps the SIGTERM signal to "a brutal reload procedure".

However, Upstart uses SIGTERM to completely shutdown processes. die-on-term inverts the meanings of SIGTERM and SIGQUIT to uWSGI.

The first will shutdown the whole stack, the second one will brutally reload it.

Socket activation (from Ubuntu 12.04)

Newer Upstart releases have an Inetd-like feature that lets processes start when connections are made to specific sockets.

You can use this feature to start uWSGI only when a client (or the webserver) first connects to it.

The 'start on socket' directive will trigger the behaviour.

You do not need to specify the socket in uWSGI as it will be passed to it by Upstart itself.

# simple uWSGI script

description "uwsgi tiny instance"
start on socket PROTO=inet PORT=3031
stop on runlevel [06]

respawn

exec uwsgi --master --processes 4 --die-on-term --wsgi-file /var/www/myapp.wsgi