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docs/rails.md

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+---
+layout: default
+title: Getting started with Fig and Rails
+---
+
+Getting started with Fig and Rails
+==================================
+
+We're going to use Fig to set up and run a Rails/PostgreSQL app. Before starting, you'll need to have [Fig installed](install.html).
+
+Let's set up the three files that'll get us started. First, our app is going to be running inside a Docker container which contains all of its dependencies. We can define what goes inside that Docker container using a file called `Dockerfile`. It'll contain this to start with:
+
+    FROM binaryphile/ruby:2.0.0-p247
+    RUN mkdir /myapp
+    WORKDIR /myapp
+    ADD Gemfile /myapp/Gemfile
+    RUN bundle install
+    ADD . /myapp
+
+That'll put our application code inside an image with Ruby, Bundler and all our dependencies.
+
+Next, we have a bootstrap `Gemfile` which just loads Rails. It'll be overwritten in a moment by `rails new`.
+
+    source 'https://rubygems.org'
+    gem 'rails', '4.0.2'
+
+Finally, `fig.yml` is where the magic happens. It describes what services our app comprises (a database and a web app), how to get each one's Docker image (the database just runs on a pre-made PostgreSQL image, and the web app is built from the current directory), and the configuration we need to link them together and expose the web app's port.
+
+    db:
+      image: orchardup/postgresql
+      ports:
+        - 5432
+    web:
+      build: .
+      command: bundle exec rackup -p 3000
+      volumes:
+        - .:/myapp
+      ports:
+        - 3000:3000
+      links:
+        - db
+
+With those files in place, we can now generate the Rails skeleton app using `fig run`:
+
+    $ fig run web rails new . --force --database=postgresql --skip-bundle
+
+First, Fig will build the image for the `web` service using the `Dockerfile`. Then it'll run `rails new` inside a new container, using that image. Once it's done, you should have a fresh app generated:
+
+    $ ls
+    Dockerfile   app          fig.yml      tmp
+    Gemfile      bin          lib          vendor
+    Gemfile.lock config       log
+    README.rdoc  config.ru    public
+    Rakefile     db           test
+
+Uncomment the line in your new `Gemfile` which loads `therubyracer`, so we've got a Javascript runtime:
+
+    gem 'therubyracer', platforms: :ruby
+
+Now that we've got a new `Gemfile`, we need to build the image again. (This, and changes to the Dockerfile itself, should be the only times you'll need to rebuild).
+
+    $ fig build
+
+The app is now bootable, but we're not quite there yet. By default, Rails expects a database to be running on `localhost` - we need to point it at the `db` container instead. We also need to change the username and password to align with the defaults set by `orchardup/postgresql`.
+
+Open up your newly-generated `database.yml`. Replace its contents with the following:
+
+    development: &default
+      adapter: postgresql
+      encoding: unicode
+      database: myapp_development
+      pool: 5
+      username: docker
+      password: docker
+      host: <%= ENV.fetch('MYAPP_DB_1_PORT_5432_TCP_ADDR', 'localhost') %>
+      port: <%= ENV.fetch('MYAPP_DB_1_PORT_5432_TCP_PORT', '5432') %>
+
+    test:
+      <<: *default
+      database: myapp_test
+
+We can now boot the app.
+
+    $ fig up
+
+If all's well, you should see some PostgreSQL output, and then—after a few seconds—the familiar refrain:
+
+    myapp_web_1 | [2014-01-17 17:16:29] INFO  WEBrick 1.3.1
+    myapp_web_1 | [2014-01-17 17:16:29] INFO  ruby 2.0.0 (2013-11-22) [x86_64-linux-gnu]
+    myapp_web_1 | [2014-01-17 17:16:29] INFO  WEBrick::HTTPServer#start: pid=1 port=3000
+
+Finally, we just need to create the database. In another terminal, run:
+
+    $ fig run web rake db:create
+
+And we're rolling—see for yourself at [localhost:3000](http://localhost:3000) (or [localdocker:3000](http://localdocker:3000) if you're using docker-osx).
+
+![Screenshot of Rails' stock index.html](https://orchardup.com/static/images/fig-rails-screenshot.png)