Antoine Kalmbach's blog

The Joy of AsciiDoc

I have always used Jekyll on Github Pages to host this site. It’s always been very pleasant to use, since Github Pages builds your site automatically. On the other hand, you can only use a limited set of plugins, so if you want a Jekyll extension, you might be out of luck, as I was recently.

I don’t mind Markdown as an input format, but it’s a very limited format. So there are several extensions to Markdown like CommonMark and kramdown addressing the deficiencies of Markdown. Even those extensions have limits.

My solution was to convert to AsciiDoc — a much richer text markup language. It contains every feature Markdown extensions have and more. Tables of contents, admonitions, and diagrams! Yes, that includes Graphviz, PlantUML and even Ditaa. I use those tools a lot, but so far haven’t used them that much here.

So the elephant in the room is that AsciiDoc doesn’t work on the default Github Pages installation since it’s not in the plugin whitelist. I had several choices:

  1. Switch to another static site generator, manually upload the published HTML to github

  2. Do the above but use another hosting system, my own VPS, whatever

  3. Stick with Github pages but build yourself and upload manually — ugh!

I didn’t want to switch site generators as I like Jekyll. Support is easy to get from the web and it’s fairly mature and popular.

I couldn’t be bothered to switch hosting systems, so I was to find another way around it. I instantly realized that option C can be solved by automating the build process. All you’re doing is running bundle exec jekyll build anyway, and uploading _site somewhere! This has got to be easy to automate on Travis.

Turned out Travis did have a Githug Pages deployment plugin, so that was easy. Hooray, my automation problems were solved!

Well, not so fast.

I wanted the Asciidoctor diagram plugin but that required the presence of the diagramming binaries, so in order for it to work I had to have the graphviz, plantuml and ditaa executables installed on the machine. And here is where I ran into problems. Travis (as of 2018) runs Ubuntu Trusty (14.04) on the default container platform, and this version of Ubuntu doesn’t have plantuml as a package.

That package is available in the unstable Debian source list, but that doesn’t work on Ubuntu anymore given Debian unstable switched over to using .tar.xz and the apt packager of Ubuntu doesn’t understand that.

Unstable builds are unstable. Who knew?

So, the fix was to add sudo: required to the .travis.yml file, and add a PPA that contains plantuml. This worked, but because I’m using sudo, my builds run on a virtual machine. Without sudo I could run on a container which build really fast. So building the site takes now about two minutes. That’s not too bad, but with a container-based build that could be less than 30 seconds.

Update (July 2021): I don’t use Jenkins CI for building the site, I use now.

Anyway, after banging my head against the beast that is dependency management, I am now happily running my own custom Jekyll build that is fully automated: I don’t have to do anything except push new content via Git, and there it is.

And I’m using AsciiDoc! Here’s a pretty ditaa picture:

Figure 1. A diagram

Here’s the source I used:

                                          |cEEE              |
                                     +--->|      Nice!       |
                                     |    |                  |
     +-------------------+           |    +------------------+
     |  Art with text?   +-----------+
               ^                             /--------------\
               |                             |cPNK          |
               +---------------------------->|   colors!    |
                                             |              |

Neat, huh? It’s a beautiful day!

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