Docs: Deploy Jekyll site with GitHub Actions (#8119)

Merge pull request 8119

docs/_docs/continuous-integration/github-actions.md

@@ -0,0 +1,213 @@
+---
+title: GitHub Actions
+---
+
+When building a Jekyll site with GitHub Pages, the standard flow is restricted for security reasons
+and to make it simpler to get a site setup. For more control over the build and still host the site
+with GitHub Pages you can use GitHub Actions.
+
+
+## Advantages of using Actions
+
+### Control over gemset
+
+- **Jekyll version** --- Instead of using the currently enabled version at `3.8.5`, you can use any
+  version of Jekyll you want. For example `4.0.0`, or point directly to the repository.
+- **Plugins** --- You can use any Jekyll plugins irrespective of them being on the
+  [supported versions][ghp-whitelist] list, even `*.rb` files placed in the `_plugins` directory
+  of your site.
+- **Themes** --- While using a custom theme is possible without Actions, it is now simpler.
+
+### 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.
+
+
+## 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.
+
+We're only going to cover builds from the `master` branch in this page. Therefore, ensure that you
+are working on the `master` branch. If necessary, you may create it based on your default branch.
+When the Action builds your site, the contents of the *destination* directory will be automatically
+pushed to the `gh-pages` branch with a commit, ready to be used for serving.
+
+{: .note .warning}
+The Action we're using here will create (or reset an existing) `gh-pages` branch on every successful
+deploy.<br/> So, if you have an existing `gh-pages` branch that is used to deploy your production
+build, ensure to make a backup of the contents into a different branch so that you can rollback
+easily if necessary.
+
+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:
+
+```yaml
+# _config.yml
+
+title: "Jekyll Actions Demo"
+```
+
+{% raw %}
+```liquid
+---
+---
+
+Welcome to My Home Page
+
+{% assign date = '2020-04-13T10:20:00Z' %}
+
+- Original date - {{ date }}
+- With timeago filter - {{ date | timeago }}
+```
+{% endraw %}
+
+
+```ruby
+# Gemfile
+
+source 'https://rubygems.org'
+
+gem 'jekyll', '~> 4.0'
+
+group :jekyll_plugins do
+  gem 'jekyll-timeago', '~> 0.13.1'
+end
+```
+
+{: .note .info}
+The demo site uses Jekyll 4 and a [third-party plugin][timeago-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
+
+GitHub Actions are registered for a repository by using a YAML file inside the directory path
+`.github/worksflows` (note the dot at the start). Here we shall employ
+[Jekyll Actions][jekyll-actions] from the Marketplace for its simplicity.
+
+Create a **workflow file**, say `github-pages.yml`, using either the GitHub interface or by pushing
+a YAML file to the workflow directory path manually. The base contents are:
+
+{% raw %}
+```yaml
+name: Build and deploy Jekyll site to GitHub Pages
+
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  github-pages:
+    runs-on: ubuntu-16.04
+    steps:
+      - uses: actions/checkout@v2
+      - uses: helaili/jekyll-action@2.0.1
+        env:
+          JEKYLL_PAT: ${{ secrets.JEKYLL_PAT }}
+```
+{% endraw %}
+
+The above workflow can be explained as the following:
+
+- We trigger the build using **on.push** condition for `master` branch only --- this prevents
+  the Action from overwriting the `gh-pages` branch on any feature branch pushes.
+- The **name** of the job matches our YAML filename: `github-pages`.
+- The **checkout** action takes care of cloning your repository.
+- We specify our selected **action** and **version number** using `helaili/jekyll-action@2.0.0`.
+  This handles the build and deploy.
+- We set a reference to a secret **environment variable** for the action to use. The `JEKYLL_PAT`
+  is a *Personal Access Token* and is detailed in the next section.
+
+Instead of using the **on.push** condition, you could trigger your build on a **schedule** by 
+using the [on.schedule] parameter. For example, here we build daily at midnight by specifying
+**cron** syntax, which can be tested at the [crontab guru] site.
+
+```yaml
+on:
+  schedule:
+    - cron:  '0 0 * * *'
+```
+
+Note that this string must be quoted to prevent the asterisks from being evaluated incorrectly.
+
+[on.schedule]: https://help.github.com/en/actions/reference/workflow-syntax-for-github-actions#onschedule
+[crontab guru]: https://crontab.guru/
+
+
+### Providing permissions
+
+The action needs permissions to push to your `gh-pages` branch. So you need to create a GitHub
+**authentication token** on your GitHub profile, then set it as an environment variable in your
+build using _Secrets_:
+
+1. On your GitHub profile, under **Developer Settings**, go to the [Personal Access Tokens][tokens]
+   section.
+2. **Create** a token. Give it a name like "GitHub Actions" and ensure it has permissions to
+   `public_repos` (or the entire `repo` scope for private repository) --- necessary for the action
+   to commit to the `gh-pages` branch.
+3. **Copy** the token value.
+4. Go to your repository's **Settings** and then the **Secrets** tab.
+5. **Create** a token named `JEKYLL_PAT` (*important*). Give it a value using the value copied
+   above.
+
+### Build and deploy
+
+On pushing any local changes onto `master`, 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 now exist on the `gh-pages`
+branch.
+
+On a successful build, GitHub Pages will **publish** the site stored on the repository `gh-pages`
+branches. Note that you do not need to setup a `gh-pages` branch or enable GitHub Pages, as the
+action will take care of this for you.
+(For private repositories, you'll have to upgrade to a paid plan).
+
+To see the **live site**:
+
+1. Go to the **environment** tab on your repository.
+2. Click **View Deployment** to see the deployed site URL.
+3. View your site at the **URL**. Make sure the `timeago` filter works as expected.
+4. Optionally **add** this URL to your repository's main page and to your `README.md`, to make it
+   easy for people to find.
+
+When you need to make further **changes** to the site, commit to `master` and push. The workflow
+will build and deploy your site again.
+
+Be sure **not to edit** the `gh-pages` branch directly, as any changes will be lost on the next
+successful deploy from the Action.
+
+## External links
+
+- [jekyll-actions] is an action available on the GitHub Marketplace and was used in this guide.
+- [jekyll-actions-quickstart] is an unofficial repository that includes a live demo of the
+  `jekyll-actions` action. That project can be used as a template for making a new site.
+
+
+[ghp-whitelist]: https://pages.github.com/versions/
+[timeago-plugin]: https://rubygems.org/gems/jekyll-timeago
+[tokens]: https://github.com/settings/tokens
+[jekyll-actions]: https://github.com/marketplace/actions/jekyll-actions
+[jekyll-actions-quickstart]: https://github.com/MichaelCurrin/jekyll-actions-quickstart

docs/_docs/deployment/automated.md

@@ -15,6 +15,7 @@ service of your choice.
 
 We have guides for the following providers:
 
+* [GitHub Actions]({{ '/docs/continuous-integration/github-actions/' | relative_url }})
 * [Travis CI]({{ '/docs/continuous-integration/travis-ci/' | relative_url }})
 * [CircleCI]({{ '/docs/continuous-integration/circleci/' | relative_url }})
 * [Buddy]({{ '/docs/continuous-integration/buddyworks/' | relative_url }})