A simple way to use Google OAuth2 to serve a protected jekyll site to users within an email domain

NOTE: This repo is a fork of benbalter/jekyll-auth, with GitHub replaced by Google OAuth2, using apcj/sinatra-google-auth (forked from csquared/sinatra-google-auth) and zquestz/omniauth-google-oauth2.

Jekyll and GitHub Pages are awesome, right? Static site, lightning fast, everything versioned in Git. What else could you ask for?

But what if you only want to share that site with people in your company? Before, you were SOL. Now, simply host the site on a free, Heroku Dyno, and whenever someone tries to access it, it will oauth them against Google, and make sure their username has the right domain. Pretty cool, huh?

1. You trust that people with a google account matching your domain are really members of your organisation, and therefore should be able to see the site.
2. A Google Application (You can always register one for free)
3. A heroku account

Follow instructions at omniauth-google-oauth2.

First, add gem 'jekyll-auth' to your Gemfile or if you don't already have a Gemfile, create a file called Gemfile in the root of your site's repository with the following content:

source "https://rubygems.org"

gem 'jekyll-auth', :git => 'https://github.com/apcj/jekyll-google-auth.git'
gem 'sinatra-google-auth', :git => 'https://github.com/apcj/sinatra-google-auth.git'

Next, cd into your project's directory and run bundle install.

Finally, run jekyll-auth new which will run you through everything you need to set up your site with Jekyll Auth.

Don't want to require authentication for every part of your site? Fine! Add a whitelist to your Jekyll's config.yml file:

jekyll_auth:
  whitelist:
    - drafts?

jekyll_auth.whitelist takes an array of regular expressions as strings. The default auth behavior checks (and blocks) against root (/). Any path defined in the whitelist won't require authentication on your site.

What if you want to go the other way, and unauthenticate the entire site except for certain portions? You can define some regex magic for that:

jekyll_auth:
  whitelist:
    - "^((?!draft).)*$"

If you've got SSL set up, simply add the following your your _config.yml file to ensure SSL is enforced.

jekyll_auth:
  ssl: true

Want to run it locally?

Just run jekyll serve as you would normally

1. export GOOGLE_CLIENT_ID=[your Google app client id]
2. export GOOGLE_CLIENT_SECRET=[your Google app client secret]
3. export GOOGLE_EMAIL_DOMAIN=[email domain]
4. jekyll-auth serve

Pro-tip #1: For sanity sake, and to avoid problems with your callback URL, you may want to have two apps, one with a local oauth callback, and one for production if you're going to be testing auth locally.

Pro-tip #2: Jekyll Auth supports dotenv out of the box. You can create a .env file in the root of site and add your configuration variables there. It's ignored by .gitignore if you use jekyll-auth new, but be sure not to accidentally commit your .env file. Here's what your .env file might look like:

GOOGLE_CLIENT_SECRET=abcdefghijklmnopqrstuvwxyz0123456789
GOOGLE_CLIENT_ID=qwertyuiop0001
GOOGLE_EMAIL_DOMAIN=example.com

Every time you push to Heroku, we take advantage of the fact that Heroku automatically runs the rake assets:precompile command (normally used for Rails sites) to build our Jekyll site and store it statically, just like GitHub pages would.

Anytime a request comes in for a page, we run it through Sinatra (using the _site folder as the static file folder, just as public would be normally), and authenticate it using apcj/sinatra-google-auth.

If they have the correct, they get the page. Otherwise, all they get bounced back to Google, where they might be able to log in with an appropriate user.