I’ve had a mysterious broken page on this site for a while - but been too busy to look into it. My Comprehensive Linux Backups with etckeeper & backupninja article has been refusing to load, and returning a weird HTTP 418 Unused status code instead. I finally made the time to figure out the cause.

It turned out that this was being caused by the Apache/PHP mod_security module. This is a static website - there’s no PHP anywhere - so why would that be a problem? Well, so far I’ve been very happily hosting the site on my old DreamHost shared hosting account - which comes with Apache & PHP installed whether you want it or not. At some point …

This site has been generated using Pelican 3.3 for over two years - and I finally found some time to upgrade to the current version of Pelican, 3.6.3. This is how I did the upgrade.

I decided to be lazy and do the upgrade in-place, instead of creating a new virtualenv and copying the content & settings over. Luckily, this worked out OK, after a bit of fiddling around.

I also decided, rather cavalierly, to upgrade all the packages in the virtualenv to their latest versions while I was at it. To do this, I upgraded pip, then used pip-review. To upgrade pip & install pip-review system wide, run this on the command line:

$ sudo -H pip install --upgrade pip
$ sudo -H pip install pip-review

Then upgrade eveything in the sites virtualenv:

$ sudo apt-get install libjpeg-dev
$ workon duncanlock.net
$ pip-review …

We use CentOS VMs at work to emulate our production environment - and it took me a while to figure out how to get the VirtualBox Guest Additions to build reliably on CentOS 6.4/5. This is what I’ve currently settled on as a reliable method.

First, make sure that you’ve got the kernel headers and tools installed that you need to build stuff:

$ sudo yum update -y
$ sudo yum install gcc kernel-devel kernel-headers dkms make bzip2 perl

Make sure that you’ve only got the current set of kernel headers installed - the one for the kernel you’re actually running. Having more than one set installed prevents this working properly. Running this should show you one version of each kernel package:

$ rpm -qa | grep kernel | sort

It should look something like this:

dracut-kernel-004-336.el6_5.2.noarch …

The weather was great this week - crisp and autumnal, with beautiful sunshine all week. It snowed a little on the local mountains and Cypress Mountain has opened for (limited) Skiing already, using the lower temperatures to make lots of extra snow. Whistler also opened this week, along with Grouse.

In other, even better news, I’m starting a fantastic new job with PHEMI Health Systems on Monday - allowing me to afford to actually go skiing. I’ll be working as a front-end web developer, helping to build their healthcare information system, directly helping to improve clinical productivity, patient outcomes and medical research. Very excited to be using my …

To create image thumbnails from a PDF document, run this in a terminal window:

$ convert -thumbnail x300 -background white -alpha remove input_file.pdf[0] output_thumbnail.png

The parameters to convert do the following things:

If you want larger thumbnails, just change the x300 parameter to match. If you want to output .jpg’s (or anything else, like .gif), just change the file …

I had a feature request for automatic figure numbering, like latex. I was revamping this plugin for Pelican 3.3 anyway - and this didn’t seem too hard - so I decided to add it.

So, the Better Figures & Images plugin now supports automatic figure numbering. To enable this for all posts, just add this to your config file:

FIGURE_NUMBERS = True

If you want to enable this per post, just add this to the metadata at the top of the post:

for restructuredText add this:

:figure_numbers: true

and for Markdown add this:

figure_numbers: true

There are quite a few changes in Pelican 3.3 - most of them minor, but a few which might mean making some changes to your site in order to upgrade. This is what I did to move my site from Pelican 3.2 to 3.3.

The change that had the biggest impact and took the most work was around image linking - caused by a combination of things. I think I was doing it wrong before and things changed in a way that meant this no longer worked. I also had to update my Better Figures & Images plugin to take this into account.

Previously, I’d been linking to my images like this, both in my theme:

/* Theme CSS Image Link */
background: #2C71B8 url(/static/images/blueprint-background.png) repeat;

{# Theme HTML/Jinja image link #}
<meta name="twitter:image" content …