Jekyll::Zopfli

Generate gzipped assets and files for your Jekyll site at build time using Zopfli compression.

API docs | GitHub repo

Performance in web applications is important. You know that, which is why you have created a static site using Jekyll. But you want a bit more performance. You're serving your assets and files gzipped, but you're making your webserver do it?

Why not just generate those gzip files at build time? And with Google's Zopfli algorithm, which generates files that are 3-8% smaller than Zlib's maximum compression?

Jekyll::Zopfli does just that. Add the gem to your Jekyll application and when you build your site it will generate gzip files for all text based files (HTML, CSS, JavaScript, etc).

Zopfli is a much slower algorithm than Zlib, so this will likely significantly slow down your site build. If you still want to generate gzip files at build time with a faster build time and Zlib's compression level, check out Jekyll::Gzip.

Zopfli is about the best compression we can get out of the gzip format, but there's more! Brotli is a relatively new compression format that is now supported by many browsers and can produce even smaller files. You can use brotli compression alongside gzip in your Sinatra app with Jekyll::Brotli.

Add this line to your application's Gemfile:

group :jekyll_plugins do
  gem 'jekyll-zopfli'
end

And then execute:

bundle install

Then add the plugin to the plugins key in your _config.yml

plugins:
  - jekyll-zopfli

Once you have the gem installed, build your Jekyll site in production mode. On Mac/Linux you can run

JEKYLL_ENV=production bundle exec jekyll build

On Windows, set the JEKYLL_ENV environment variable to "production". Check out this blog post on setting environment variables on Windows. Then run:

bundle exec jekyll build

In your destination directory (_site by default) you will find gzipped versions of all your text files.

Jekyll::Zopfli only runs when the environment variable JEKYLL_ENV is set to production as dealing with gzipping files is unnecessary in development mode and just slows down the site build.

By default, Jekyll::Zopfli will compress all files with the following extensions:

• '.html'
• '.css'
• '.js'
• '.json'
• '.txt'
• '.ttf'
• '.atom'
• '.stl'
• '.xml'
• '.svg'
• '.eot'

You can supply your own extensions by adding a zopfli key to your site's _config.yml listing the extensions that you want to compress. For example to only compress HTML, CSS and JavaScript files, add the following to _config.yml:

zopfli:
  extensions:
    - '.html'
    - '.css'
    - '.js

If you host your Jekyll site on AWS S3 you can take advantage of Jekyll::Zopfli for compressing the whole site. The only difference is that you need to replace the uncompressed file with the gzipped file (that is, without a .gz extension). To enable this in Jekyll::Zopfli turn the replace_files setting to true.

zopfli:
  replace_files: true

You will likely need to adjust your web server config to serve these precomputed gzip files. See below for common server configurations:

For nginx, you need to turn on the gzip_static module. Add the following in the relevant http, server or location block:

gzip_static on;

The ngx_http_gzip_static_module module is not built by default, so you may need to enable using the --with-http_gzip_static_module configuration parameter.

In either a <Directory> section in your Apache config or in an .htaccess file, add the following:

AddEncoding gzip .gz
RewriteCond %{HTTP:Accept-encoding} gzip
RewriteCond %{REQUEST_FILENAME}.gz -f
RewriteRule ^(.*)$ $1.gz [QSA,L]

TODO: instructions for other web servers like HAProxy, h2o etc.

Do you know how to do this for a different server? Please open a pull request or an issue with the details!

After checking out the repo, run bundle install to install dependencies. Then, run bundle exec rspec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/philnash/jekyll-zopfli. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

The gem is available as open source under the terms of the MIT License.

Everyone interacting in the Jekyll::Zopfli project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.