Advance Jekyll

This is part two in a three part series on static site generators.

  1. Why Static Site Generators
  2. Getting Starting With Jekyll
  3. Advance Jekyll (You are here)

In the previous post I talked about Jekyll, a popular static site generator written in Ruby. In fact, it’s what this site has been using for a while. During that time, I’ve picked up some tips and tricks that I want to share with you today.

The things you find in here are not best practices, absolute truths, or even the best way to do things. With development, there’s a thousand different ways to do something, these just happen to be what I found works.

In This Post

Deploy To S3

GitHub Pages offers a free solution for hosting a Jekyll site on a platform you probably already use. This works wonderfully for the majority of sites out there. However, because it is a hosted solution, there’s limitations to it. You can’t run custom plugins and the build process has to be completely done through Jekyll. The power of Jekyll is really unlocked when you deploy to another platform that you have control over.

Because Jekyll outputs static files, the options for where you can deploy your site are endless. You could manually upload the files to a web server you own or even automate that process with a tool like rsync.

This site is hosted on Amazon S3. It was a product I was already using and I don’t have to worry about security, updates, or any of the other things you have to with a normal web server. They have static website hosting built in, but it can be a bit confusing to get setup. Instead, I recommend using a tool called s3_website. Not only does it manage S3 static hosting configuration, it can upload your site for you (and only the files that changed), use AWS CloudFront to distribute your website, manage HTTP cache control and gzipping, and much more. Obviously you don’t want to commit your AWS access or secret keys, so either keep the file local, or commit an example copy of it without those values.

Manage Your Dependencies

As you dive deeper into customizing and streamlining your Jekyll site, you’ll find yourself using lots of different tools. Using a dependency management tool like Bundler can help easy that and provide consistency between any different environments you may be using.

To get you started, here is a starting Gemfile for Jekyll.

source 'https://rubygems.org'

gem 'jekyll'

You can also target a specific version of Jekyll.

source 'https://rubygems.org'

gem 'jekyll', '~> 3.3'

Make sure you also commit your Gemfile.lock file to manage specific versions of dependencies.

Stop Excluding Files

We’ve added two more files to our directory that we probably don’t want to be a part of our final site. If we add more tools like Gulp or Yarn, we would need to add more files to exclude from our site. Jekyll allows you to define the source of your site. By default this is the current directory (.), we can change that with the source option. Either on the command line or even better, our _config.yml file.

source: site

This directory can contain only files that Jekyll uses to generate the site and you won’t have to worry about extra files getting into your build.

Plugins

Now that we have all the boring stuff out of the way, we can start getting to the cool parts. Arguably one of the most powerful features of Jekyll is it’s plugin system. There are plugins out there to generate sitemaps, RSS feeds, add SEO tags, and more. There’s even support for some plugins on GitHub Pages.

There are a couple different ways to install plugins in Jekyll. The first is to list it in your _config.yml.

gems:
  - jekyll-sitemap

If you’re using Bundler, you can use the jekyll_plugins group and those will automatically be registered with Jekyll.

# Gemfile

group :jekyll_plugins do
  gem 'jekyll-sitemap'
end

You can find out all about Jekyll plugins at their documentation.

Custom Liquid Tags

Liquid is a pretty powerful templating language. With Jekyll we can build on top of that and add custom tags. This is done by as a Jekyll plugin, all we need is a little Ruby.

As an example, I want a tag that strips out all extra whitespace. To do this, I create a file called _plugins/spaceless.rb.

module Jekyll
  class Spaceless < Liquid::Block

    def initialize(tag_name, text, tokens)
      super
    end

    def render(context)
      text = super.to_s
      lines = text.split("\n").map { |line| line.strip }.reject! { |line| line.empty? }
      lines.join("\n") if lines
    end

  end
end

Liquid::Template.register_tag('spaceless', Jekyll::Spaceless)

Now we have access to a spaceless tag in our site.

{% spaceless %}
     This won't have whitespace before it
{% endspaceless %}

Custom Filters

You can also add Liquid filters. Filters are Ruby modules that export all their methods to Liquid.

module Jekyll
  module MyFilters
    def asset_url(input)
      "http://my-cdn.example.com/assets/#{input}"
    end
  end
end

Liquid::Template.register_filter(Jekyll::MyFilters)

Filters are applied via pipe ({{ profile.jpg | asset_url }}).

Assets

I remember when Jekyll didn’t support Sass or CoffeeScript out of the box, luckily that’s all changed and adding Sass to your site is easy. Concatenating CSS/JS, optimizing images, and adding in third-party assets aren’t as easy. If Jekyll out of the box works for you, that’s great. If you need something a little bit more advance, read on. I’m going to go over two different options. Gulp or Jekyll Assets.

Gulp

Gulp is a build system for JavaScript. I’ve personally used it for other projects and I love it. I’m not a front-end developer by any means, but it’s really easy to use. Unfortunately, there’s a million different ways to configure your build. If you’re looking for a place to start, I would check out generator-jekyllized.

I was never able to get a build pipeline that I liked in Gulp, so I don’t have much insight here, but there are tons of sites out there that have done this.

Jekyll Assets

I was never able to get a build pipeline in Gulp that I liked, so I decided to go with a pure Ruby option of Jekyll 3 Assets. If you’re not comfortable with NodeJS or Gulp, but need something better than what Jekyll provides out of the box, this might be a good solution for you. Jekyll Assets is an asset pipeline for Jekyll 3 using Sprockets, the same system Rails uses. With the support for Sprockets, I was able to switch over to Jekyll Assets from my old Gulp build in about 10 minutes.

Testing

We have this badass site. It builds all our assets for us, we’ve customized it with some third-party plugins and even a few of our own. It’s perfect, how do we make sure it stays that way? We can test it!

What can we test? First we can test that everything with Jekyll is ok. Let’s run the doctor command.

$ jekyll doctor

We should also test that all the links in our site are going to resolve to a working page. To do this, we use the [html-proofer][html-proofer] gem. This will scan all links in HTML pages and make sure they return a real page. I’ve had this catch links that were broken on old posts.

$ jekyll build
$ htmlproof [site-dest]

For most sites, this is probably sufficient. Let’s say you have a site that uses a lot of custom plugins or logic in your templates that you want to test. We could use a tool like Selenium or a lighter tool like PhantomJS. I used CasperJS for this site. It offers some really useful tools specific for testing. Here is an example test:

casper.test.begin('Homepage', 7, function suite(test) {
  casper.start('http://localhost:4000/', function() {
    test.assertTitle("Matthew Loberg · Software Engineer");
    test.assertNotVisible('#sidebar', 'Sidebar is not visible');
    test.assertElementCount('.post', 5, 'There should be 5 posts on the first page.');
    this.click('.older');
  }).then(function() {
    test.assertUrlMatch(/page2/, "We are on the second page of posts.");
    test.assertElementCount('.post', 5, 'There should be 5 posts on the second page.');
    this.click('.sidebar-toggle');
  }).then(function() {
    test.assertVisible('#sidebar', 'Sidebar should be visible after clicking hamburger.');
    test.assertElementCount('#sidebar .social ul li', 2);
  }).run(function() {
    test.done();
  });
});

You can check out the full test for this site on GitHub.

Additionally you could do some CSS regression testing using a tool like BackstopJS, Wraith, or PhantomCSS.

Automated Deployments

One of the things I really missed about GitHub Pages was the ability to push a change to my site and have it automatically built. With s3_website, I need to remember to build and deploy my site. If I’m away from home, I can’t make a change with GitHub’s interface and have it automatically build.

Or can I?

With a tool such as TravisCI it is possible to have automatic deploys on push. First let’s create a .travis.yml that just builds and tests our site.

language: ruby
sudo: false
rvm:
  - 2.1

cache:
  directories:
    - vendor

env:
  global:
    - TZ=America/Chicago # Makes sure posts are generated with the right timestamp
    - NOKOGIRI_USE_SYSTEM_LIBRARIES=true # speeds up installation of html-proofer
    - JEKYLL_ENV=production

install: bundle install --jobs=3 --retry=3 --path vendor --standalone --deployment

script:
  - bundle exec jekyll build
  - bundle exec htmlproof build

Here we’re using a Ruby 2.1 Travis container to build our site. I’ve set a custom install script that installs gems to vendor and then caches that directory to speed up the installation process. For our test script, we build the site and then run [html-proofer][html-proofer] against the build.

Travis has an after_script option that will run after a successful build. We don’t want to expose our AWS access and secret key, so we need to add them as encrypted variables. Then change our s3_website.yml to load those from the environment instead.

s3_id: <%= ENV['S3_ID'] %>
s3_secret: <%= ENV['S3_SECRET'] %>
s3_bucket: <%= ENV['S3_BUCKET'] %>
cloudfront_distribution_id: <%= ENV['CF_ID'] %>

Finally, we only want to run this on the master branch. Travis gives an option to only run on certain branches.

language: ruby
sudo: false
rvm:
  - 2.1

cache:
  directories:
    - vendor

env:
  global:
    - TZ=America/Chicago # Makes sure posts are generated with the right timestamp
    - NOKOGIRI_USE_SYSTEM_LIBRARIES=true # speeds up installation of html-proofer
    - JEKYLL_ENV=production
    - secure: xxx
    - secure: xxx
    - secure: xxx
    - secure: xxx

install: bundle install --jobs=3 --retry=3 --path vendor --standalone --deployment

script:
  - bundle exec jekyll build
  - bundle exec htmlproof build

after_success: bundle exec s3_website push

branches:
  only:
    - master

If we make a change to our site using GitHub’s interface, it should automatically build and push our site. Huzzah!

Wrapping Up

This is only scratching the surface of what Jekyll and static site builders are capable of. If you have any useful tips or tricks you’ve learned with Jekyll, please share them in the comments.