Pelican and GitHub Pages workflow

This blog is powered by Pelican and hosted through GitHub using GitHub Pages.
In this post I’ll describe the workflow I use when deploying new posts.

For those of you not familiar with these technologies, Pelican is a static site generator – meaning you can write your content in a format such
as Markdown, and Pelican will automatically generate the HTML files for you; and GitHub Pages is
a service provided by GitHub for hosting a website under the <your-username>.github.io URL.

Using Pelican and GitHub Pages is quite easy. There’s one annoying little thing though… GitHub Pages assumes
the master branch contains the root folder to be served to the world. If you’re using Pelican’s default settings, the output
folder is the folder you want to serve. output contains the generated website’s files.
A natural choice of how to organize the files inside the repository
would be to define pelican’s root folder – the parent of output – as the root of the repository. But GitHub Pages needs
output to be the root. Bummer…

There are those
who solve it using two separate repositories: one for the website “source” files, and
one for the output which will be served using GitHub Pages.

I personally don’t like breaking my blog into two repositories. I want to keep everything in one place, so I chose to solve the problem
using branches and git hooks.

The first step is to create two branches:

• source will contain the blog’s “source” files, namely – all the files such as the content folder which contains the actual posts, and pelicanconf.py file.
• master will contain only the contents of output.

These branches will obviously live in my GitHub Pages repo
(https://github.com/yoel-zeldes/yoel-zeldes.github.io),
and since the master branch contains output‘s contents, a user navigating to yoel-zeldes.github.io
will be presented with the goodness of my blog.

Unfortunately, manually maintaining these two branches is cumbersome. Git hooks to the rescue!

Git has a mechanism to execute custom scripts when certain important actions occur. In my case, whenever I push a commit to the source branch,
I’d like the master branch to get updated with the new contents of output. This can be done using the pre-push hook, which is executed –
you guessed it – just before a push occurs.

All you have to do is create a file named .git/hooks/pre-push with the following content:

#!/bin/sh
while read local_ref local_sha remote_ref remote_sha
do
        if [ "$remote_ref" = "refs/heads/source" ]
        then
                echo 'pushing output folder (production version) to master...'
                pelican content -o output -s publishconf.py
                echo anotherdatum.com > output/CNAME
                ghp-import output
                git push --no-verify git@github.com:yoel-zeldes/yoel-zeldes.github.io.git gh-pages:master
                pelican content -o output
        fi
done

exit 0

1. The first thing the script does is iterating over the commits that are about to be pushed. Specifically, only commits that are pushed to the
   source branch are of interest to us.
2. If commits are pushed to source, it executes pelican command using publishconf.py. This will generate the production version of the blog into output.
3. It then creates a CNAME file, which is needed since I use a custom domain (http://anotherdatum.com).
4. The GitHub Pages Import tool is used for copying the contents of output to a branch named gh-pages.
5. gh-pages is pushed to the remote master branch. --no-verify skips the pre-push hook so this script won’t run again.
6. pelican is executed again to generate the development version of my blog, so I’ll be able to write the next post.

Now, whenever I push to source, and only to source, master gets updated with the new contents. Cool!

One last small detail: I added output to the .gitignore file. This way, the source branch won’t include this folder.
We don’t really want to put it under version control – it would be like putting other types of generated files such as
.pyc or .o under version control.