diff --git a/.github/workflows/gitlab.yml b/.github/workflows/gitlab.yml
new file mode 100644
index 00000000..62b020af
--- /dev/null
+++ b/.github/workflows/gitlab.yml
@@ -0,0 +1,144 @@
+name: GitLab Test template
+on:
+  push:
+    branches: gh-pages
+  pull_request:
+jobs:
+  check-template:
+    name: ${{ matrix.lesson-name }} (${{ matrix.os-name }})
+    if: github.repository == 'carpentries/styles'
+    runs-on: ${{ matrix.os }}
+    continue-on-error: ${{ matrix.experimental }}
+    strategy:
+      fail-fast: false
+      matrix:
+        lesson: [carpentries/lesson-example]
+        os: [ubuntu-20.04]
+        experimental: [false]
+        include:
+          - os: ubuntu-20.04
+            os-name: Linux
+          - lesson: carpentries/lesson-example
+            lesson-name: (CP) Lesson Example
+            experimental: false
+            os: ubuntu-20.04
+            os-name: Linux
+    defaults:
+      run:
+        shell: bash  # forces 'Git for Windows' on Windows
+    env:
+      RSPM: 'https://packagemanager.rstudio.com/cran/__linux__/focal/latest'
+    steps:
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: '2.7'
+          bundler-cache: true
+
+      - name: Set up Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: '3.x'
+
+      - name: Install GitHub Pages, Bundler, and kramdown gems
+        run: |
+          gem install github-pages bundler kramdown kramdown-parser-gfm
+
+      - name: Install Python modules
+        run: |
+          python3 -m pip install --upgrade pip setuptools wheel pyyaml==5.3.1 requests
+
+      - name: Checkout the ${{ matrix.lesson }} lesson
+        uses: actions/checkout@master
+        with:
+          repository: ${{ matrix.lesson }}
+          path: lesson
+          fetch-depth: 0
+
+      - name: Sync lesson with carpentries/styles
+        working-directory: lesson
+        run: |
+          echo "::group::Fetch Styles"
+          if [[ -n "${{ github.event.pull_request.number }}" ]]
+          then
+            ref="refs/pull/${{ github.event.pull_request.number }}/head"
+          else
+            ref="gh-pages"
+          fi
+
+          git config --global user.email "team@carpentries.org"
+          git config --global user.name "The Carpentries Bot"
+
+          git remote add styles https://github.com/carpentries/styles.git
+          git fetch styles $ref:styles-ref
+          echo "::endgroup::"
+          echo "::group::Synchronize Styles"
+          # Sync up only if necessary
+          if [[ $(git rev-list --count HEAD..styles-ref) != 0 ]]
+          then
+
+            # The merge command below might fail for lessons that use remote theme
+            # https://github.com/carpentries/carpentries-theme
+            echo "Testing merge using recursive strategy, accepting upstream changes without committing"
+            if ! git merge -s recursive -Xtheirs --no-commit styles-ref
+            then
+
+              # Remove "deleted by us, unmerged" files from the staging area.
+              # these are the files that were removed from the lesson
+              # but are still present in the carpentries/styles repo
+              echo "Removing previously deleted files"
+              git rm $(git diff --name-only --diff-filter=DU)
+
+              # If there are still "unmerged" files,
+              # let's raise an error and look into this more closely
+              if [[ -n $(git diff --name-only --diff-filter=U) ]]
+              then
+                echo "There were unmerged files in ${{ matrix.lesson-name }}:"
+                echo "$(git diff --compact-summary --diff-filter=U)"
+                exit 1
+              fi
+            fi
+
+            echo "Committing changes"
+            git commit -m "Sync lesson with carpentries/styles"
+          fi
+          echo "::endgroup::"
+
+      - name: Download gitlab-runner
+        working-directory: lesson
+        run: |
+          wget -O gitlab-runner https://gitlab-runner-downloads.s3.amazonaws.com/latest/binaries/gitlab-runner-linux-amd64
+          chmod +x gitlab-runner
+
+      - name: Build carpentries example lesson using gitlab-runner
+        working-directory: lesson
+        run: |
+          # GitLab expects the final folder to be "public"
+          # gitlab-runner runs a docker container on which we
+          # mount _site as the expected output directory
+          # Chown is necessary only to ensure the files are owned by
+          # the user outside the container
+          # NOTE when using gitlab-runner CI_REPOSITORY_URL is set
+          # to /path/to/repo regardless of --env passed below.
+          # When running in GitLab CI it will be set to the repo URL
+          ./gitlab-runner exec docker pages \
+            --docker-volumes "$(pwd)/_site:/public" \
+            --env "GITLAB_CI=true" \
+            --env "CI_PROJECT_NAME=lesson-example" \
+            --env "CI_DEFAULT_BRANCH=my-custom-branch" \
+            --env "CI_REPOSITORY_URL=https://github.com/${{ matrix.lesson }}" \
+            --env "CI_PAGES_URL=https://pages.github.com" \
+            --env "CI_PROJECT_TITLE=${{ matrix.lesson-name }}" \
+            --env "CI_MERGE_REQUEST_SOURCE_BRANCH_NAME=patch-1" \
+            --post-build-script "rm -rf /public/* && cp -R public/* /public && chown -R $(id -u):$(id -g) /public"
+
+      - name: List generated files
+        run: ls -l _site
+        working-directory: lesson
+
+      - name: Check that CI_DEFAULT_BRANCH propagated correctly
+        run: grep '/edit/my-custom-branch/index\.md' _site/index.html
+        working-directory: lesson
+
+      - run: make lesson-check-all
+        working-directory: lesson
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
new file mode 100644
index 00000000..86decc77
--- /dev/null
+++ b/.gitlab-ci.yml
@@ -0,0 +1,22 @@
+---
+image:
+  name: carpentries/lesson-docker:latest
+  entrypoint: [""]
+
+variables:
+  LC_ALL: "C.UTF-8"
+  MAKEFLAGS: "-j 8"
+  # Override the Gemfile used in the lesson-docker image
+  # with the one included in the current repository
+  BUNDLE_GEMFILE: Gemfile
+
+pages:
+  stage: deploy
+  script:
+    - make site
+    - mv _site public
+  artifacts:
+    paths:
+      - public
+  only:
+    - gh-pages
diff --git a/Gemfile b/Gemfile
index 8d69492b..3d6ae3b2 100644
--- a/Gemfile
+++ b/Gemfile
@@ -7,8 +7,52 @@ git_source(:github) { |repo_name| "https://github.com/#{repo_name}" }
 # Synchronize with https://pages.github.com/versions
 ruby '>=2.7.1'
 
-gem 'github-pages', group: :jekyll_plugins
+group :jekyll_plugins do
+  if ENV["GITHUB_ACTIONS"]
+    # When building GitHub Pages via GitHub Actions
+    gem 'github-pages'
+  else
+    # Or elsewhere and if additional gems are necessary.
+    # Note that the 'github-pages' plugin disables any
+    # non-whitelisted plugin.
+    # See PR #521 for additional context
+
+    # Dependency list from 'github-pages'
+    # See: https://github.com/github/pages-gem/blob/75fd58be0f294a6bf55a1990643838d5984a1f62/lib/github-pages/dependencies.rb#L8
+    gem 'jekyll', '>= 3.9.0'
+    gem 'jekyll-sass-converter', '>= 1.5.2'
+    # Converters
+    gem 'kramdown', '>= 2.3.1'
+    gem 'kramdown-parser-gfm', '>= 1.1.0'
+    gem 'jekyll-commonmark-ghpages', '>= 0.1.6'
+    # Misc
+    gem 'liquid', '>= 4.0.3'
+    gem 'rouge', '>= 3.26.0'
+    # gem 'github-pages-health-check', '>= 1.17.1'  # Not necessary outside GitHub
+    # Plugins
+    gem 'jekyll-redirect-from', '>= 0.16.0'
+    gem 'jekyll-sitemap', '>= 1.4.0'
+    gem 'jekyll-feed', '>= 0.15.1'
+    gem 'jekyll-gist', '>= 1.5.0'
+    gem 'jekyll-paginate', '>= 1.1.0'
+    gem 'jekyll-coffeescript', '>= 1.1.1'
+    gem 'jekyll-seo-tag', '>= 2.7.1'
+    # gem 'jekyll-github-metadata', '>= 2.13.0'  # Not necessary outside GitHub
+    gem 'jekyll-avatar', '>= 0.7.0'
+    gem 'jekyll-remote-theme', '>= 0.4.3'
+    # Plugins to match GitHub.com Markdown
+    gem 'jemoji', '>= 0.12.0'
+    gem 'jekyll-mentions', '>= 1.6.0'
+    gem 'jekyll-relative-links', '>= 0.6.1'
+    gem 'jekyll-optional-front-matter', '>= 0.3.2'
+    gem 'jekyll-readme-index', '>= 0.3.0'
+    gem 'jekyll-default-layout', '>= 0.1.4'
+    gem 'jekyll-titles-from-headings', '>= 0.5.3'
+    # Extra dependency that allows accessing ENV variables in other CI environments
+    gem 'jekyll-environment-variables', '>= 1.0.1'
+  end
+end
 
 if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('3.0.0')
     gem 'webrick', '>= 1.6.1'
-end
\ No newline at end of file
+end
diff --git a/_includes/gh_variables.html b/_includes/gh_variables.html
index 3fdae4ac..5966cec8 100644
--- a/_includes/gh_variables.html
+++ b/_includes/gh_variables.html
@@ -1,4 +1,12 @@
 {% comment %}
+This file was initially used to provide access to GitHub variables
+available when rendering websites through GitHub Pages.
+It has since then been expanded to also work with GitLab Pages,
+although with some limitations due to platform differences.
+Particularly, the variable "repo_info" is set to false when rendering
+through GitLab Pages. The value false is the same set by github-pages
+plugin when GitHub's API cannot be reached.
+
 When rendering websites locally, `site.github.url` doesn't get resolved properly
 unless a GitHub Personal Access Token is set up and available in the
 environment. This leads to warnings and errors when trying to serve the site
@@ -7,7 +15,23 @@
 GitHub where `site.github.url` is defined.
 {% endcomment %}
 
-{% if jekyll.environment == "production" %}
+{% if site.env.GITLAB_CI %}
+
+{% comment %}
+This block applies when running in a GitLab CI environment
+See https://docs.gitlab.com/ee/ci/variables/predefined_variables.html
+for GitLab CI specific variables.
+{% endcomment %}
+
+{% assign repo_name = site.env.CI_PROJECT_NAME %}
+{% assign repo_info = false %}
+{% assign default_branch = site.env.CI_DEFAULT_BRANCH %}
+{% assign repo_url = site.env.CI_REPOSITORY_URL %}
+{% assign search_domain_url = site.env.CI_PAGES_URL %}
+{% assign project_title = site.env.CI_PROJECT_TITLE %}
+{% assign source_branch = site.env.CI_MERGE_REQUEST_SOURCE_BRANCH_NAME %}
+
+{% elsif jekyll.environment == "production" and site.github %}
 
 {% comment %}
 First, get the name of the repository