Setting up Django and Python 2.7 on Red Hat Enterprise 6 the easy way

Recently, I needed to get Django installed with Python 2.7 on Red Hat Enterprise Linux 6. As this is not a directly supported activity, I wanted to document how I went about it. As you might imagine, the generally expected method for install would be to grab the Python 2.7 source tree and then build it. Obviously, that can be a lot of work; is not particularly repeatable; and, potentially, exposes you to more security flaws. As a result, I decided to try to leverage a "new'ish" technology developed (in the open) by Red Hat called Software Collections. An in depth discussion of Software Collections is for another post, for now we just need to know that Software Collections are rpms that contain all (or most) of their supporting libraries, install under /opt, are updatable through yum, and, the core software collections code (scl-utils) is supported by Red Hat. A number of collections have been created and released by the community at http://bit.ly/fedora-scl.

OK, getting started. I created a new VM using a RHEL 6.3 image on an instance of RHOS (Red Hat Open Stack),

which is still in preview status (and available to anyone who signs up here) but works well to try this out. First weirdness I ran into was that there was a sudoers file (/etc/sudoers) but sudo (the binary) wasn't actually installed. So:

su
yum install sudo
exit

and, back in action. Now we can add a repo for the Python 2.7 scl (short for "Software Collection") by creating/editing a file in /etc/yum.repos.d. For the software collections, I prefer having one file, scl.repo, and adding all the repos I use to it (YMMV).

sudo vi /etc/yum.repos.d/scl.repo
c/p from http://people.redhat.com/bkabrda/scl_python27.repo (or follow the link from the Fedora SCL page) into the file
:wq

If you want to be all slick and one-liney...

sudo sh -c 'wget -qO- http://people.redhat.com/bkabrda/scl_python27.repo >> /etc/yum.repos.d/scl.repo'

I don't want to actually include the repo file here as it may change over time. You could also just wget the file and put that in repos.d but I like having all the scl info in one place and so I create one repo file with all the repos in it.

Now we install very easily using:

sudo yum install python27

then we get:

scl -l
python27
[me@localhost ~]$ scl enable python27 bash
[me@localhost ~]$ python -V
Python 2.7.3

Now, even though there is a software collection for mysql 5.5, Django works with any version of mysql after 5.0.3. As a result, we are going to stick with the one in RHEL 6 default.

sudo yum install mysql-server mysql

OK.. looks like everything should be installed correctly, now we can install Django
To install Django I want to use pip as that is what the Django folks recommend. You may need to pass the LD_LIBRARY_PATH to sudo because, depending on your configuration, sudo may be configured to strip any LD paths out of your sudo environment by default.

Easy way to check for this is to:

sudo sudo -V (as root, run sudo, with "version" as an option)

If you see "LD_*" or something similar under "Environment variables to remove" then you know you need to pass it. The error you will get is basically python being unable to find its linked libraries. You could also avoid all of this by backing up a bit, su'ing as root directly, and then running scl enable as root.

sudo LD_LIBRARY_PATH=$LD_LIBRARY_PATH easy_install pip
sudo LD_LIBRARY_PATH=$LD_LIBRARY_PATH pip install django

Django also requires a library called MySQLdb which is available as an rpm on RHEL 6. However, the normal installation method of this library is not sufficient for our needs. As a result, we need to install using pip. However, this is a binary install and requires not only gcc but also the mysql header files to build. The next two lines should get it installed for you.

sudo yum install gcc mysql-devel
sudo LD_LIBRARY_PATH=$LD_LIBRARY_PATH pip install MySQL-python

Now you are ready to proceed with Django. We won't be covering how to use or run Django in this post as it is not really any different than it would be normally. You can find a number of docs that cover this subject. However, be sure that you have "scl enabled" python 2.7 before running any of these operations.
For example:

scl enable python27 bash
django-admin.py startproject mytest_django
(modify settings.py to point at your database, enable admin, etc)
python manage.py runserver {insert your IP here}:8000

In a future post, we will cover running Django with Apache's httpd.