GitHub Actions

When building a Jekyll site with GitHub Pages, Jekyll runs in an environment restricted for security reasons, yet containing numerous whitelisted plugins and themes to make it simpler to get a site set up.

The only workaround to have control over the build environment and gemset yet use GitHub Pages to host the site was previously by building elsewhere and pushing the built directory contents to the gh-pages branch on your repository.

However, GitHub now provides you with the option to use their in-house CI/CD product named GitHub Actions to build and deploy (host) your Jekyll site with complete control over the build environment and gemset.

Advantages of using Actions

Control over gemset

• Jekyll version --- Instead of using the classic GitHub Pages-provided version specified in the Dependency versions list, you can use any version of Jekyll you want. For example {{ site.version }}, or point directly to the repository via the Gemfile.
• Plugins --- You can use any Jekyll plugins irrespective of them being whitelisted by GitHub, including any *.rb files placed in the _plugins directory of your site.
• Themes --- While using a custom theme is possible without Actions, it is now possible to use themes depending on features introduced in newer versions of Jekyll.

{: .note .info} If you are migrating from the classic flow but want to keep using a GitHub-hosted theme, you may use the jekyll-remote-theme plugin, add any required dependencies of your theme (previously bundled by default) into your _config.yml and Gemfile and set the remote_theme: <owner>/<repo_name> theme repository slug correctly in your _config.yml.

Workflow Management

• Customization --- By creating a workflow file to run Actions, you can specify custom build steps, use environment variables.
• Logging --- The build log is visible and can be tweaked to be verbose, so it is much easier to debug errors using Actions.
• Caching --- The ruby/setup-ruby action makes it possible to cache installed gems automatically instead of having to download the bundle on each build.

Workspace setup

The first and foremost requirement is a Jekyll project hosted at GitHub. Choose an existing Jekyll project or follow the [quickstart]({{ '/docs/' | relative_url }}) and push the repository to GitHub if it is not hosted there already.

The Jekyll site we'll be using for the rest of this page, initially consists of just a _config.yml, an index.md page and a Gemfile. The contents are respectively:

# _config.yml

title: "Jekyll Actions Demo"

{% raw %}

---
---

Welcome to My Home Page

{% assign date = '2020-04-13T10:20:00Z' %}

- Original date - {{ date }}
- With timeago filter - {{ date | timeago }}

{% endraw %}

# Gemfile

source 'https://rubygems.org'

gem "jekyll", "~> 4.2"

group :jekyll_plugins do
  gem "jekyll-timeago", "~> 0.13.1"
end

{: .note .info} The demo site uses Jekyll 4 and a third-party plugin, both of which are currently not whitelisted for use on GitHub pages. The plugin will allow us to describe how far back a date was from today. e.g. If we give a date as 2016-03-23T10:20:00Z and the current date is 2020-04-13T10:20:00Z, then the output would be 4 years and 3 weeks ago.

{: .note .info} The action we're using takes care of installing the Ruby gems and dependencies. While that keeps the setup simple for the user, one may encounter issues if they also check-in Gemfile.lock if it was generated with an old version of Bundler.

Setting up the Action

1. Go to the Settings tab on your repository.
   1. Click Pages under Code and automation.
   2. Change Source under Build and deployment from Deploy from a branch to GitHub Actions.
2. Go to the Actions tab on your repository.
   1. Start a New workflow and search for Jekyll.
   2. Click Configure under the Jekyll workflow (not GitHub Pages Jekyll workflow).
   3. Review the change and click Commit changes.

Build and deploy

On pushing any local changes onto the default branch, the action will be triggered and the build will start.

To watch the progress and see any build errors, check on the build status using one of the following approaches:

• View by commit
  • Go to the repository level view in GitHub. Under the most recent commit (near the top) you’ll see a status symbol next to the commit message as a tick or X. Hover over it and click the details link.
• Actions tab
  • Go to the repository's Actions tab. Click on the jekyll workflow tab.

If all goes well, all steps will be green and the built assets will be uploaded to GitHub Pages.

To see the live site, go to the Deployments tab on your repository, and click on the deployed site URL.

When you need to make further changes to the site, commit to the default branch and push. The workflow will build and deploy your site again.

External links

• starter-workflows is the official repository providing the workflow template used in this guide.