ruby-rack-app-tutorial.md

type	title	shortdesc	tags	keywords	str_replace_dict	aliases
docs	Rack full tutorial	How to write a hello world web application using Rack and deploy it on Clever Cloud.	deploy	ruby rack	@application-type@ Ruby	/doc/deploy/application/ruby/tutorials/ruby-rack-app-tutorial

Overview Introduction

Currently, Clever Cloud supports Rack-based applications. Created in 2007, Rack has become the de-facto standard for ruby web applications and is used in many frameworks such as Ruby on Rails.

Configure your Rack based application

Mandatory configuration

To follow this tutorial, you will need:

• Ruby >= 1.9.2 (w/ Rubygems)
• Bundler (gem install bundler and you're good to go!)
• Your preferred editor
• Git (for the deploy part)

{{< callout type="info">}} To manage your gems and ruby versions, we recommend rbenv. If you use a system-wide installation of ruby, You will have to use sudo with the gem and bundle commands, or use arguments that will make gem and bundle install the gem in directories you have write-permissions in. {{< /callout >}}

My application does not exists already

Create a Ruby + Rake application locally

Our demo for this tutorial is here: https://helloworld-rack-demo.cleverapps.io/.

You can also doing it manually by following these instructions:

mkdir helloworld-rack
cd helloworld-rack
touch hello.rb config.ru Gemfile ## or gems.rb

Inside hello.rb put the following:

class HelloWorld
  def call(env)
   [200, {"Content-Type" => "text/plain"}, ["Hello world!"]]
  end
end

Inside the config.ru (That is, the main Rack entry-point) put:

require './hello'
run HelloWorld.new

The gems.rb or Gemfile file will contain our dependencies:

source 'https://rubygems.org'

gem 'rack', '~>1.5.1'


gem "puma", "~> 6.4"

We don't need any more dependencies. The gems.rb or Gemfile is mandatory to deploy on Clever Cloud.

Do not forget to init an empty git repository with $ git init

Test your application locally

To test your application, just fetch the dependencies using bundler:

$ bundle install
Fetching gem metadata from https://rubygems.org/..........
Resolving dependencies...
Using rack (1.5.2)
Using puma (6.4.2)
Using bundler (1.3.5)
Your bundle is complete!
Use `bundle show [gemname]` to see where a bundled gem is installed.

And start your application:

$ bundle exec rackup
[2013-09-16 17:35:26] INFO  WEBrick 1.3.1
[2013-09-16 17:35:26] INFO  ruby 2.0.0 (2013-06-27) [x86_64-linux]
[2013-09-16 17:35:26] INFO  WEBrick::HTTPServer#start: pid=5656 port=9292

You can now test with your browser at localhost:9292.

You can now read My application already exists

My application already exists

{{% content/create-application %}}

{{% content/set-env-vars %}}

{{% content/env-injection %}}

To access environment variables from your code, just get them from the environment with ENV["MY_VARIABLE"].

{{% content/deploy-git %}}

{{% content/link-addon %}}

{{% content/more-config %}}