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The Python-based Django framework has been chosen at UC Berkeley to provide additional functionality within deployed instances of CollectionSpace. Uses include reporting and other collection administration tasks, as well as outward facing, public web-sites for presentation of the data stored in a CollectionSpace instance.This document describes

Normally, you may assume that this environment already exists and is operating on UC Berkeley VMs used for CollectionSpace. Indeed, if you have a choice, you should choose a VM that already has the required packages installed.

But if you are unlucky enough to have to do it yourself, here are the steps we have used at UC Berkeley to feather the bed for CSpace-Django webapps.

Below are the steps necessary for installing and running a Django web application, using the Apache Webserver and WSGI as the front-end. Much of the configuration of a Django application will be project-specific, so this is not intended as a one-size-fits-all approach.

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Contents

Installation

Install Python

Django requires any Python version from 2.6.5 to 2.7,x. To ensure Python is installed and is the required version, type into the shell:

python -V
Python 2.7.1

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Be sure that httpd-tools are installed, as well:

httpd.x86_64                       2.2.15-29.el6_4
httpd-tools.x86_64                 2.2.15-29.el6_4

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If not installed, on Yum systems, it can be installed with the command:

yum install httpd
yum install httpd-tools

And on Aptitude systems:

apt-get install apache2
apt-get install apache2-utils

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If no appropriate binary version of mod_wsgi is available, download the source code and unpack it in a convenient place:

tar -zxf mod_wsgi-3.4.tar.gz
cd mod_wsgi-3.4
./configure
make

This will probably not be good enough, since you will probably be wanting to compile against a different version of python (why else would you be compiling from source?), so the configure command might look more like:

./configure --with-python=/usr/local/bin/python2.7

If you get a compiler error about not finding the apache apxs file then add yet another option:

./configure --with-python=/usr/local/bin/python2.7  --with-apxs=/usr/local/apache/bin/apxs

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When the mod_wsgi source code has been configured and compiled successfully, run

make install

which will copy the compiled mod_wsgi.so file into the apache2 or httpd modules directory.

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Pip is a tool for installing and managing Python packages.

• Begin by checking whether Pip is installed, and if so, which version:

  Code Block
  lang bash
  sudo yum list installed | grep -i pip

  or

  Code Block
  lang bash
  which pip

• If Pip is not installed, install it.
  • On RedHat systems, this is a slightly roundabout process:
    

    1. Install the python-devel package:

       Code Block
       lang bash
       sudo yum install python-devel

    2. Install python-setuptools:

       Code Block
       lang bash
       sudo yum install python-setuptools

       Info
       python-distribute might work, too: http://docs.python-guide.org/en/latest/starting/install/linux/

    3. Install Pip:

       Code Block
       lang bash
       sudo easy_install pip

    4. Update setuptools using Pip:

       Code Block
       lang bash
       sudo pip install setuptools --upgrade

  • For apt-based systems, the process is straight-forward:

    Code Block
    lang bash
    sudo apt-get install python-pip python-dev build-essential

    Note
    The python-dev and build-essential packages are recommended to install along, because it isn't possible to install any Python module that ships with a C extension without them later on.

• Upgrade Pip (same process for apt- and yum-compatible systems)

  Code Block
  lang bash
  sudo pip install --upgrade pip

  Tip
  Please install any Python libraries that you might need.

Install Virtualenv

• Check that virtualenv is installed

  Code Block
  lang bash
  which virtualenv

• If it isn't already present, install virtualenv:

  Code Block
  lang bash
  sudo pip install virtualenv

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• Check that virtualenvwrapper is installed

  Code Block
  lang bash
  which virtualenvwrapper.sh

• If it isn't already present, install Virtualenvwrapper (same for apt- and yum-compatible systems

  Code Block
  lang bash
  sudo pip install virtualenvwrapper

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Make a Django directory

• Make a Django directory. This directory will contain all of your virtualenvs and Django projects:

  Code Block
  cd /usr/local/share sudo mkdir django

• Give read/write access to the users who will need to create and edit Django webapps. The following instructions assume that you have previously created a Unix group called developers that includes these users.

  Code Block
  sudo chgrp developers django

• The entire directory tree leading to a Django app must be readable by whatever account is running the http server, typically apache or, on Ubuntu, www-data. To facilitate this, make the Django directory readable and executable by everyone. This will ensure that Apache can read the entire directory path down to the level of each of your Django projects. (By default, the parent /usr/local/share directory already is readable and executable by everyone.)

  Code Block
  sudo chmod 775 django

  Warning
  Ed. note - this makes the django directory writable by group. Explain why we do this?

Create a virtual environment

• Create a virtual environment in a subdirectory within the Django directory. (The virtual environment in this example happens to be named "venv26", referring to the use of a Python 2.6.x version within that environment.)

  Code Block
  cd django sudo virtualenv --no-site-packages venv26 sudo chgrp developers venv26/ sudo chmod g+w venv26/

• Make the virtual environment active:

  Code Block
  cd venv26 source bin/activate

  Note
  You should see the virtual machine name (venv26) displayed in your shell prompt once you've activated the vm.

Install Django

• Install Django within the virtual environment:

  Code Block
  sudo sh -c "source ../venv26/bin/activate; pip install django"

  Note
  A note about the syntax used above: Running the sequence of commands as root installs Django within the activated virtual environment. If run as two separate steps, the command sudo pip install django would exit virtualenv and install Django in a system directory.

(Optional) Install Python module to support Postgres bindings:

• Install psycopg2

  Code Block
  export PATH=$PATH:/usr/pgsql-9.2/bin pip install psycopg2

  Warning
  Ed.note: not yet tested.

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It's a good idea at this point to create a 'hello world' Django project, to verify that Apache and Django are configured correctly to talk to one another. To create a "hello world" project, change to your Django directory and enter the Django startproject command:

cd /usr/local/share/django
django-admin.py startproject hello_world

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At some place inside each of your Django project directories, Apache Web Server will need to be able to write files, so make another directory inside of the hello_world directory named, for instance, apache. (There's nothing special about the name, and you call it anything that seems appropriate.)

cd hello_world
mkdir apache

Make whatever account is running the http server, such as apache or (on Ubuntu) www-data, the owner of that directory with full access rights; e.g.

sudo chown apache:apache apache
sudo chmod u+rwx

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Change to Apache's directory for user-created configuration files, conf.d. Depending on your system, this directory might be located at /etc/httpd/conf.d or /etc/apache2/conf.d; e.g.

cd /etc/httpd/conf.d

Configure Apache directives

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• WSGISocketPrefix

WSGISocketPrefix run/wsgi

• Directory

  Warning
  Ed. note: Is it necessary to grant Apache permissions beyond the django/ directory?

  Code Block
  <Directory "/usr/local/share/django/hello_world"> Order allow,deny Allow from all </Directory>

• WSGIScriptAlias

  Code Block
  WSGIScriptAlias /hello_world /usr/local/share/django/hello_world/hello_world/wsgi.py

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WSGIDaemonProcess hello_world_wsgi
<Location /hello_world
   WSGIProcessGroup hello_world_wsgi
</Location>

A further change required to the above configuration, if you use daemon mode, is that you can’t use WSGIPythonPath; instead you should use the python-path option to WSGIDaemonProcess, for example:

WSGIDaemonProcess hello_world_wsgi python-path=/path/to/hello_world project:/path/to/venv/lib/python2.7/site-packages

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The following is a sample configuration for two Django projects, pahma_project and cspace_django_project, running in parallel in Daemon mode:

<!-- We're using the same virtual environment for both projects, since their dependencies do not conflict, located at /usr/local/share/django/vir274 -->
WSGIDaemonProcess pahma_project_wsgi python-path=/usr/local/share/django/pahma_project:/usr/local/share/django/vir274/lib/python2.7/site-packages user=apache group=apache
WSGIDaemonProcess cspace_django_project_wsgi python-path=/usr/local/share/django/cspace_django_project:/usr/local/share/django/vir274/lib/python2.7/site-packages user=apache group=apache

<!-- Each project has a wsgi.py file in it -->
WSGIScriptAlias /pahma_project /usr/local/share/django/pahma_project/cspace_django_site/wsgi.py
WSGIScriptAlias /cspace_django_project /usr/local/share/django/cspace_django_project/cspace_django_site/wsgi.py

WSGISocketPrefix run/wsgi

<!-- the location for each webapp should be unique, and should match the value of WSGI_BASE in the project's wsgi.py file -->
<Location /pahma_project>
   WSGIProcessGroup  pahma_project_wsgi
</Location>
<Location /cspace_django_project>
   WSGIProcessGroup  cspace_django_project_wsgi
</Location>

<!-- for running two cspace django projects alongside each other, you will have to give the static root a unique name here, and change the STATIC_URL in that project's settings.py file to match -->
Alias /static  /usr/local/share/django/pahma_project/static_root
Alias /cspace_django_project_static  /usr/local/share/django/cspace_django_project/static_root

<Directory "/usr/local/share/django/pahma_project/static_root">
   Order deny,allow
   Deny from all
   Allow from all
</Directory>
<Directory "/usr/local/share/django/cspace_django_project/static_root">
   Order deny,allow
   Deny from all
   Allow from all
</Directory>

WSGIDaemonProcess ... user=apache group=apache

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