Tommy Chheng

Need a quick web app done in Ruby? While Ruby on Rails is a great framework, it is overkill for a simple one page application. Enter: Sinatra.

Sinatra is a light-weight Ruby framework intended for fast web applications. In fact, here is all you need for a hello world app:


# myapp.rb
require 'rubygems'
require 'sinatra'
get '/' do
'Hello world!'
end


You can read more about Sinatra syntax on their documentation page.

This guide will get you started from the ground up to setting up and deploying a sinatra app on Nginx/Passenger with Capistrano and Git. I choose Passenger because it allows you to run multiple ruby applications easier than the traditional Mongrel setup.

Install Passenger/Nginx

Install the passenger gem:
gem install passenger

Install Nginx and Passenger Module:
passenger-install-nginx-module

The instructions from the install scripts are pretty much self-explanatory. More information on the official Phusion Passenger page. I also recommend installing Phusion’s Ruby Enterprise Edition for more memory savings.

Make sure your nginx.conf file is configured to include external files, notice the include statements at the end:


user deploy;
worker_processes 1;
error_log /var/log/nginx/error.log;
pid /var/run/nginx.pid;
events {
worker_connections 1024;
}
http {
include /opt/nginx/conf/mime.types;
default_type application/octet-stream;
passenger_root /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/gems/passenger-2.2.2;
passenger_ruby /usr/bin/ruby;
passenger_max_pool_size 2;
access_log /var/log/nginx/access.log;
sendfile on;
keepalive_timeout 65;
tcp_nodelay on;
gzip on;
server_names_hash_bucket_size 128;
include /opt/nginx/conf/conf.d/*.conf;
include /opt/nginx/conf/sites-enabled/*;
}


Create a Nginx entry file in /opt/nginx/conf/sites-available/APP_NAME:


server {
listen 80;
server_name YOURDOMAINNAME.HERE;
root /u/apps/production/APP_NAME/current/public;
passenger_enabled on;
}


Symlink this in the sites-enabled folder:

ln -s /opt/nginx/conf/sites-available/APP_NAME /opt/nginx/conf/sites-enabled/APP_NAME


A basic Sinatra template

Now, let’s get a basic Sinatra app on the server. To speed things along, clone this Sinatra template app:
git clone git://github.com/tc/sinatra-template.git

This includes a Rack config file(config.ru) and a cap deploy script.

This was forked from zapnap/sinatra-template but I removed datamapper since I didn’t intend to use a database. I also added a cap template script.

Edit the deploy.rb file and add in your git url/username/app_name


#========================
#CONFIG
#========================
set :application, "APP_NAME"
set :scm, :git
set :git_enable_submodules, 1
set :repository, "GIT_URL"
set :branch, "master"
set :ssh_options, { :forward_agent => true }
set :stage, :production
set :user, "deploy"
set :use_sudo, false
set :runner, "deploy"
set :deploy_to, "/u/apps/#{stage}/#{application}"
set :app_server, :passenger
set :domain, "DOMAIN_URL"
#========================
#ROLES
#========================
role :app, domain
role :web, domain
role :db, domain, :primary => true
#========================
#CUSTOM
#========================
namespace :deploy do
task :start, :roles => :app do
run "touch #{current_release}/tmp/restart.txt"
end
task :stop, :roles => :app do
# Do nothing.
end
desc "Restart Application"
task :restart, :roles => :app do
run "touch #{current_release}/tmp/restart.txt"
end
end


Deploying to Server

Let’s deploy the app onto the server now. I will assume you already have ssh key authentication setup on the server.

Now, setup your directories using

cap deploy:setup


and deploy your code from your git repo.

cap deploy


That’s it! Passenger is able to recognize Sinatra app through the RACK interface. You should be able to visit the domain and see your app up:

The cap script will automatically restart the app by touching the restart.txt file.