Create a Debian package for your Django application

This post is about building a Debian package to deploy a Django application on a Debian server.

The package will take care of the following:

• Install application
• Web server configuration (in our case: Lighttpd with fastcgi)
• Init.d script to start/stop Django server

We will also use a debconf template to ask 1 question to the user to make our package more dynamic.

Let’s assume you have a Django application located in /usr/share/djangoapp . This is where you have settings.py, manage.py, views.py etc…

First thing, we need to create a folder debian and copy the Django app folder into it:

mkdir ./debian
mkdir -p ./debian/usr/share/
cp -r /usr/share/djangoapp ./debian/usr/share/

We also need to create a folder names DEBIAN in debian/

mkdir ./debian/DEBIAN

DEBIAN files

This folder needs to contain the following files:

• control
• config
• conffiles
• templates
• postinst
• postrm
• preinst
• prerm

control

This is the most important file in a Debian package. It gives information on the package itself along with some dependencies. In our case, it looks like this:

Package: djangoapp
Version: 0.1-1
Section: devel
Priority: optional
Architecture: all
Depends: python, python-django, python-flup, debconf, lighttpd
Maintainer: Laurent Luce <laurent@tomnica.com>
Description: short description
 long description

Depends consists of a list of packages required for our package to run properly.

config

config is a script responsible for asking questions to the user before the package gets installed. In our case, we will ask one simple question: what is your full name?

#!/bin/sh -e

# Source debconf library.
. /usr/share/debconf/confmodule

# server type?
db_input critical djangoapp/username || true
db_go

As you can see, you need to include debconf confmodule to add configuration support. Our question is critical.

Wait a minute, where is the question definition? It is defined in the templates file

templates

This is where we define our question: string type.

Template: djangoapp/username
Type: string
Description: Username:
This package requires your full name.

conffiles
This file contains the configuration files generally located under /etc . We add our Django start script and the lighttpd configuration file.

/etc/init.d/django
/etc/lighttpd/lighttpd.conf

preinst
This script is run before the package gets installed.

#!/bin/bash
set -e

# stop django server
if [ -f /etc/init.d/django ]
then
  invoke-rc.d django stop
fi

postinst
This script is run after the package is unpacked.

#!/bin/sh
set -e

# Source debconf library.
. /usr/share/debconf/confmodule

db_get djangoapp/username
username="$RET"
# do what you want with this username

# register django
update-rc.d django defaults 90 >/dev/null
# start django
invoke-rc.d django start

db_stop

postrm
This script is run after the package is removed.

#!/bin/bash
set -e

if [ "$1" = "purge" -a -e /usr/share/debconf/confmodule ]; then
    # Source debconf library.
    . /usr/share/debconf/confmodule
    # Remove my changes to the db.
    db_purge
fi

if [ "$1" = "remove" ]; then

# Source debconf library.
. /usr/share/debconf/confmodule

# remove Django start script
update-rc.d -f django remove

# Remove my changes to the db.
db_purge
fi

prerm
This script is run before the package is removed.

#!/bin/bash
set -e

# stop django server
invoke-rc.d django stop

Web server configuration

Here is what needs to be modified in the web server configuration (in our case, lighttpd.conf):

mod_fastcgi needs to be added to the server modules.

The Django server will be running on port 3033 so we need to specify the connection here:

fastcgi.server = (
  "/djangoapp.fcgi" => (
    "main" => (
      # Use host / port instead of socket for TCP fastcgi
      "host" => "127.0.0.1",
      "port" => 3033,
      "check-local" => "disable",
  ))
)

Django init.d script

Now is time to add our Django start/stop script:

#! /bin/sh
### BEGIN INIT INFO
# Provides:          FastCGI servers for Django
# Required-Start:    networking
# Required-Stop:     networking
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Django FastCGI
#

DJANGO_SITE="djangoapp"
SITE_PATH=/var/www
RUNFILES_PATH=$SITES_PATH/tmp
HOST=127.0.0.1
PORT_START=3033
RUN_AS=www-data

set -e

PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
DESC="Django FastCGI"
NAME=$0
SCRIPTNAME=/etc/init.d/$NAME

#
#       Function that starts the daemon/service.
#
d_start()
{
    # Starting all Django FastCGI processes
    echo -n ", $DJANGO_SITE"
    if [ -f $RUNFILES_PATH/$DJANGO_SITE.pid ]; then
        echo -n " already running"
    else
       start-stop-daemon --start --quiet \
                       --pidfile $RUNFILES_PATH/$DJANGO_SITE.pid \
                       --chuid $RUN_AS --exec /usr/bin/env -- python \
                       $SITE_PATH/$DJANGO_SITE/manage.py runfcgi \
                       host=$HOST port=$PORT \
                       pidfile=$RUNFILES_PATH/$DJANGO_SITE.pid
    fi
}

#
#       Function that stops the daemon/service.
#
d_stop() {
    # Killing all Django FastCGI processes running
    echo -n ", $DJANGO_SITE"
    start-stop-daemon --stop --quiet --pidfile $RUNFILES_PATH/$SITE.pid \
                          || echo -n " not running"
    if [ -f $RUNFILES_PATH/$DJANGO_SITE.pid ]; then
        rm $RUNFILES_PATH/$DJANGO_SITE.pid
    fi
}

ACTION="$1"
case "$ACTION" in
    start)
        echo -n "Starting $DESC: $NAME"
        d_start
        echo "."
        ;;

    stop)
        echo -n "Stopping $DESC: $NAME"
        d_stop
        echo "."
        ;;

    restart|force-reload)
        echo -n "Restarting $DESC: $NAME"
        d_stop
        sleep 1
        d_start
        echo "."
        ;;

    *)
        echo "Usage: $NAME {start|stop|restart|force-reload}" >&2
        exit 3
        ;;
esac

exit 0

This script needs to be placed in ./debian/etc/init.d/

You will also need to create a link from /var/www/djangoapp to /usr/share/djangoapp

changelog, changelog.Debian and copyright

Those are required for Debian packages:

changelog

djangoapp (0.1-1) unstable; urgency=low

  * Initial release.
    + Initial package

 -- Laurent Luce <laurent@tomnica.com>  Fri, 01 Jan 2010 00:00:00 +0000

In our case, changelog.Debian is identical to changelog.

copyright

DjangoApp

Copyright: bla bla

2010-01-01

The home page of xxx is at: 
http://www.xxx.com

Copyright xxx 2010

We need to place those files properly:

mkdir -p ./debian/usr/share/doc/djangoapp
cp changelog changelog.Debian copyright ./debian/usr/share/doc/djangoapp/
gzip --best ./debian/usr/share/doc/djangoapp/changelog
gzip --best ./debian/usr/share/doc/djangoapp/changelog.Debian

Build package

We need to fix the permission of our package files:

find ./debian -type d | xargs chmod 755

We build the package and verify it:

fakeroot dpkg-deb --build debian
mv debian.deb DjangoApp_0.1-1_all.deb
lintian DjangoApp_0.1-1_all.deb

Our package is now ready to be deployed.

If you enjoyed this article, check out my web app Gourmious and discover and share your favorite restaurant dishes.