Tech Stuff

Here's a recipe for adding (and formatting) captions to images in Drupal using Entity View Modes, File Entity, and Media 2.0. A word of warning first. All of the required modules are either unstable or dev releases and so for those not willing to deploy these modules to a production Drupal install - this article should at the least give you an idea of what's possible and what's coming.

Design Goals

The objective is to allow a user to upload or select an image using the Media module, as well as choose a layout for the image. The media embed tags (non-HTML) placed into the body of the node/post will then be filtered by the media module, resulting in markup containing an image, surrounded by div elements with appropriate class attributes for position and styling. jQuery, or client-side JavaScript will not be required, and there will be a dedicated caption field. No other specialised 'captioning' or image modules will be required.

Requirements

You'll need all three of the above modules at the following releases: File Entity 7.x-2.0-unstable7 Entity View Modes 7.x-1.0-beta3 Media 7.x-2.x-dev

I recently suffered a UDP flood attack on my little virtual private server (VPS), and thought I'd describe the steps I went through to discover and fix the problem.

Symptoms

Periodically, my server would stall and become unresponsive. It was effectively dead, although not down. These 'stalling' events would last from 5-20 minutes, and then the server would come back up. Looking at my Munin charts told me that my public ethernet interface (eth0) was being flooded. Here's a particularly bad day:

And this was after I had rate limited eth0 to 2mbits/sec using tc (more on tc in a bit). CPU usage and interrupts for eth0 also spiked. So something was flooding eth0, and stalling the server.

Here's a solution to a problem I was trying to solve in Ruby. I wanted to create a 23 bit data structure, that would hold three values. A 14 bit year, a 4 bit month and a 5 bit day. Each of these bit sizes are the minimum number of bits required to support a maximum value of 9999 for years, 12 for months and 31 for days (with months and days optional - hence the custom data structure). Using the bitwise & operator, you can either mask (protect) or zero out bit values. And then using the bitwise | operator - you can turn bits back on. In Ruby you can create and manipulate binary literals directly using the 0b prefix.