Persistent IPython notebooks in Windows

I’ve been using IPython for about six months, and I’ve grown to love the web-based notebook interface. It’s became my go-to environment when I want to do simple calculations, or test a new idea in Python. It’s also a lovely environment for literate programming, and I wish I’d had it for my university coursework.¹

On my Mac, I’ve been using some scripts by Nathan Grigg to keep my IPython notebook server running continuously, and to give it a nicer hostname. Over the weekend, I realised that 1) IPython would be really useful at work, and 2) since my work computer is a PC, I need to adapt his scripts to work with Windows.

This post explains how to get a persistent IPython notebook on Windows. The ideas are based on Nathan’s post, but the implementation is a little different.

Install IPython

I installed Python 3.4², then set up a virtualenv and installed IPython:

C:\Users\AWLC> C:\Python34\Scripts\virtualenv.exe ipython
C:\Users\AWLC> ipython\Scripts\activate.bat
(ipython) C:\Users\AWLC> pip install ipython

For some reason, this didn’t install all the notebook dependencies. I needed to install a few more modules:

(ipython) C:\Users\AWLC> pip install pyzmq jinja2 tornado jsonschema

Then I could start an IPython notebook server with ipython notebook, but I had to run that command myself, every time I logged in. Time to automate that step.

Always running server with Task Scheduler

First I created a Batch script that started my IPython server:

C:\Users\AWLC\ipython\Scripts\ipython.exe notebook^
 --no-browser^
 --port=80^
 --ip=127.0.0.13^
 --notebook-dir=C:\Users\AWLC\Drive\Notebooks
PAUSE

Most of those options are fairly self-explanatory. The only line worth discussing is --ip, where I’ve used 127.0.0.13 instead of the conventional 127.0.0.1. In IPv4, the entire 127.0.0.0/8 address block is available for loopback. That means any 127.x.x.x address can act like a localhost address (at least on Windows; a little extra work is required to set this up on OS X).

Like Nathan, I have lots of processes serving to localhost, but I use different loopback addresses – rather than different ports – to keep them separate. I find this simpler than setting up Apache and configuring port forwarding.

Having created this script, now it needs to run whenever I log in. I created a new item in Task Scheduler with a “Start a program” action, and the following program:

cmd /c start "IPython notebook" /min "C:\Users\AWLC\bin\start_ipython.bat"

Here start_ipython.bat is the Batch script I wrote above. I also supply the /min flag, which auto-minimises the command window. I haven’t found a way to hide it entirely (at least not without giving the script admin permissions), but it’s better than nothing.

I also tweaked the task settings so that it auto-runs at login and tries to resume if the task fails.

So now I have an always-running IPython server at http://127.0.0.13. Finally, let’s give it a nicer hostname.

Setting a virtual host

The hosts file in Windows lives at C:\Windows\System32\drivers\etc\hosts. After opening that (as an administrator), I added the following line:

127.0.0.13 py

The change took effect immediately: now py resolves to 127.0.0.13, and I can access my IPython server by going to py in my browser.