---
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 apt-get update -qq && apt-get install -y build-essential libpq-dev
    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. For more information on how to write Dockerfiles, see the [Dockerfile tutorial](https://www.docker.io/learn/dockerfile/) and the [Dockerfile reference](http://docs.docker.io/en/latest/use/builder/).

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('DB_1_PORT_5432_TCP_ADDR', 'localhost') %>
      port: <%= ENV.fetch('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)