Jekyll themes with GitHub

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Jordan Trbuhovic
10 July 2019 • 4 mins

Recently we covered turning a Jekyll theme into a Gem and hosting it privately on GemFury. In this post we’re demonstrating how you can host your theme on GitHub . GitHub allow both public and private repository/theme hosting.

Create a theme repository

First, create a repository on GitHub. Anyone can use your theme if the repository is public.

Clone the repository to your local machine and open it from the command line. The Jekyll new-theme command builds a basic theme structure that includes the _layouts, _includes and _sass directories. Start building a theme by entering the following into your command line:

$ jekyll new-theme mytheme

This generates a basic Jekyll site which other sites can inherit from. The Jekyll new-theme command also creates a gemspec file (mytheme.gemspec). This holds the version, and other relevant theme details.

It is good practice to add all relevant details to the .gemspec file, and the file. You will receive build errors if the .gemspec and files contain “FIXME” and “TODO” entries.

Push these changes to your theme’s repository on GitHub to ensure everything is up to date.

Using Themes

To build a themed site the Gemfile should specify where to download the theme from. Open your site’s Gemfile and add the following line:

gem 'mytheme', '>= 0.1.0', :git => ''

Jekyll also needs to know that the site is using a theme. Specify the theme you are using within the site’s _config.yml file.

theme: mytheme

Using Different Versions

It is also possible to specify a particular theme ref/commit, branch, or tag to use.

gem 'mytheme', '>= 1.2.4', :git => ''
:git => '', :ref => '6afec'
:git => '', :branch => '1-2-beta'
:git => '', :tag => 'v1.2.4'

Private Themes

Private repositories can be accessed using OAuth Tokens instead of personal credentials. To create an OAuth Token follow these steps:

  1. Open your GitHub account settings
  2. Select Developer Settings from the left-hand menu
  3. Select Personal Access Tokens from the left-hand menu
  4. Select the Generate New Token button

Set the relevant permissions which the token will have access to. Once the token has generated, note it and keep it private. Keys are not recoverable once they’re lost.

To use a private theme the repository URL specified in the site’s Gemfile needs to include the token:

gem 'mytheme', '>= 0.1.0', :git => ''

If you include the TOKEN string in your Gemfile directly, you can start to receive a lot of warnings from the GitGuardian. In this case, you can keep your secret key in CloudCannon environment variables. In CloudCannon navigate to Settings > Configuration > Environment Variables.

Add the key GIT_SECRET and add your token as the value. Then inside of your Gemfile import this environment variable and replace the TOKEN string with variable.

auth = ENV['GIT_SECRET']
gem 'mytheme', '>= 0.1.0', :git => 'https://#{auth}'

Be sure to specify the theme you are using within the site’s _config.yml file.

Updating Themes

The Gemfile.lock will always lock to a specific commit/version. Run the bundle update theme_name command to pull new theme changes/versions.


Using themes with GitHub can be more convenient while you’re developing. With GitHub repositories, you don’t need to release a gem for every change or update. Once a theme is stable it may be more beneficial to use a Gem. Using Gems help to keep consistency with versioning across your sites.

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