By default, GitHub Pages uses Jekyll (a ruby based static site generator), but you can also publish any generated files provided you have an index.html file in the root of a branch called gh-pages or master. In addition you can publish from a docs directory in your repository. That branch name can also be manually changed in the settings of a repository. However, this only applies to publishing in a custom domain, i.e., if you want to publish to a GitHub-provided web service under the github.io domain, you can only use the master branch of your repository, as explained here, so we will focus on the method that will work regardless of the domain.

We can use any continuous integration (CI) server to build and deploy our site. For example:

• Github Actions
• Travis CI

Travis CI

We are going to use Travis CI to automatically publish the site. If you are not using Travis already, you will need to login with the GitHub OAuth and activate Travis for the repository. Don't forget to also check if your repository allows GitHub Pages in its settings.

Ensure that Travis can access your theme

Depending on how you added your theme, Travis may not know how to access it. The best way to ensure that it will have full access to the theme is to use git submodules. When doing this, ensure that you are using the https version of the URL.

$ git submodule add {THEME_URL} themes/{THEME_NAME}

Allowing Travis to push to GitHub

Before pushing anything, Travis needs a Github private access key to make changes to your repository. If you're already logged in to your account, just click here to go to your tokens page. Otherwise, navigate to Settings > Developer Settings > Personal Access Tokens. Generate a new token and give it any description you'd like. Under the "Select Scopes" section, give it repo permissions. Click "Generate token" to finish up.

Your token will now be visible. Copy it into your clipboard and head back to Travis. Once on Travis, click on your project, and navigate to "Settings". Scroll down to "Environment Variables" and input a name of GH_TOKEN with a value of your access token. Make sure that "Display value in build log" is off, and then click add. Now Travis has access to your repository.

Setting up Travis

We're almost done. We just need some scripts in a .travis.yml file to tell Travis what to do.

NOTE: The script below assumes that we're taking the code from the code branch and will generate the HTML to be published in the master branch of the same repository. You're free to use any other branch for the Markdown files but if you want to use <username>.github.io or <org>.github.io, the destination branch MUST be master.

language: minimal

before_script:
  # Download and unzip the zola executable
  # Replace the version numbers in the URL by the version you want to use
  - curl -s -L https://github.com/getzola/zola/releases/download/v0.9.0/zola-v0.9.0-x86_64-unknown-linux-gnu.tar.gz | sudo tar xvzf - -C /usr/local/bin

script:
  - zola build

# If you are using a different folder than `public` for the output directory, you will
# need to change the `zola` command and the `ghp-import` path
after_success: |
  [ $TRAVIS_BRANCH = code ] &&
  [ $TRAVIS_PULL_REQUEST = false ] &&
  zola build &&
  sudo pip install ghp-import &&
  ghp-import -n public -b master &&
  git push -fq https://${GH_TOKEN}@github.com/${TRAVIS_REPO_SLUG}.git master

If your site is using a custom domain, you will need to mention it in the ghp-import command: ghp-import -c vaporsoft.net -n public for example.

Credits: this page is based on the article https://vaporsoft.net/publishing-gutenberg-to-github/