Getting started with pip/virtualenv

If you find yourself in a situation where you have to work with multiple Django projects on the same system, where each one requires a specific version of Django(and some other libraries), or even specific version of Python(2.5/2.6..), the combination of virtualenv and pip will make your life easier.

virtualenv is tool to create isolated Python environments.

pip is a Python package installer, much like easy_install. It’s complementary with virtualenv; you’ll use pip to install, upgrade, or uninstall packages in isolated virtualenvs.

In this post, I’ll show a simple workflow that will give you the basics on how to use these tools to manage multiple Django projects.

Installation

First, get these tools installed on your machine. If you have easy_install set up, you can install pip by just issuing the following command

sudo easy_intsall pip

Now install virtualenv, using pip itself

sudo pip install virtualenv

Creating virtualenvs

Now that you have them installed, let’s try creating some virtualenvs. It’s good to have a specific location on your machine where you would have all the virtualenvs. I personally like to have them under ~/.virtualenvs directory.

Create the directory

mkdir -p ~/.virtualenvs

Navigate into it

cd ~/.virtualenvs

Create a virtualenv

virtualenv -p python2.5 --no-site-packages projectA

The ‘-p’ option specifies which version of the Python interpreter you want to use for the virtualenv(In case you have multiple in your system). If not specified, the default interpreter will be used.

The ‘–no-site-packages’ option means do NOT inherit any packages from /usr/lib/python2.5/site-packages (or wherever your global site-packages directory is). Use this if you don’t want depend on the global packages and want more isolation.

Finally ‘projectA’ is the name of the virtualenv, named after the project itself(not a rule, just a good convention).

You’ll see the directory projectA created once the command prompt returns. This is the virtualenv, feel free to explore it.

Activating/Deactivating the virtualenv

Once pip have finished downloading and installing the packages, hopefully without any glitches, activate the virtualenv

source ~/virtualenvs/projectA/bin/activate

You should see “(projectA)” in your command prompt.

To deactivate it type ‘deactivate’ in your prompt and hit enter. The “(projectA)” should disappear.

So now you have an isolated and functional environment for your Django project. You should go ahead and create a new virtualenv with more recent versions of Python/Django as your homework.

I hope you’ve got the basics properly. Check out the online docs to learn more advanced usages of these tools.

In the next post, I’ll talk about virtualenvwrapper, a tool that makes managing multiple virtualenvs a little easier.

Advertisements

5 thoughts on “Getting started with pip/virtualenv

  1. I would actually suggest not to create virtenv folder hidden. The point of virtualenv is mainly isolating projects with it’s own python environment. So it makes sense to create the project inside a virtualenv folder structure. Therefore it is better to create a visible folder (let’s say, projects) and inside there create envs (say, env1, env2, etc.). And create src folder where you put your main project.

    I like it this way because it keeps everything in a single folder tree. Also it makes the cdvirtualenv command from virtualenvwrapper more useful.

  2. @Nasim I actually keep the virtualenv in the project directory when I’m deploying the app on a server. But on a local machine, I take the ‘all virtualenvs in one location’ approach, because it makes managing them with the virtualenvwrapper easier.

  3. note you have a typo
    source ~/virtualenvs/projectA/bin/activate
    should be
    source ~/.virtualenvs/projectA/bin/activate

    Thank you for the tutorial !

  4. Pingback: Web Technology Operational Transformation | William Maio

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s