Launching locally: two ways to skin a cat

I realized that in Part 1 I did not cover launching the app to hit it from the browser. It’s easy! To launch the app, use ruby app_name.rb. This will fire up a mongrel instance on port 4567 for your viewing pleasure.

Once you have defined your rack configuration (see below), you can also run the app inside rack locally with rackup config.ru to test your rack settings. This will launch rack inside mongrel on port 9292. Thanks to @jnunemaker for the tip. In fact, John’s article is what I used as a basis for my deployment, with a few changes to support file based view templates.

Rack Configuration

To configure the application to run on rack under Passenger, you need to define a rack configuration file. Passenger expects that file to be named config.ru (see Deploying a Rack-based Ruby application in the Passenger documentation). Here is a minimum config.ru to run the application:

require 'rubygems'
require 'sinatra'
 
disable :run
 
require 'urlunwind.rb'
run Sinatra.application

The only real configuration there is disable :run. This prevents Sinatra from starting a mongrel on port 4567 when the app file is required. This configuration would work for an app that uses no file based templates, and does not reference anything in public/. If you run this config with rackup on url_unwind (rackup config.ru), you’ll see errors like:

Errno::ENOENT: No such file or directory - /opt/local/bin/views/index.haml




This is because rack by default sets its base directory to be the path to the called executable (and on my machine, rackup lives in /opt/local/bin/). So we’ll need to explicitly set the paths:

require 'rubygems'
require 'sinatra'
 
disable :run
set :views, File.dirname(__FILE__) + '/views'
set :public, File.dirname(__FILE__) + '/public'
set :app_file, __FILE__
 
require 'urlunwind.rb'
run Sinatra.application

Now the app should run properly with rackup.

Logging

Sinatra uses rack’s built in logging to log requests, and these log messages get printed to standard out. It would be nice to log these to a file, and we can do that as well in config.ru (based on this tip from Chris Schneider). We’ll also need to turn error raising back on, since by default Sinatra swallows errors in production mode:

require 'rubygems'
require 'sinatra'
 
disable :run
set :env, :production
set :raise_errors, true
set :views, File.dirname(__FILE__) + '/views'
set :public, File.dirname(__FILE__) + '/public'
set :app_file, __FILE__
 
log = File.new("log/sinatra.log", "a")
STDOUT.reopen(log)
STDERR.reopen(log)
 
require 'urlunwind.rb'
run Sinatra.application

This allows you to add your own logging messages as well, just puts, print, or p@ whatever you want to log. *Note:* you will need to create the @log/ directory for this to work.

Deploy with Capistrano

I used Capistrano to deploy to Dreamhost, and based my Capfile of off John’s directions here. I modified it a bit to pull from github, and to create the tmp/ and log/ directories if they do not exist. Here is my Capfile:

#-*-ruby-*-
load 'deploy' if respond_to?(:namespace) # cap2 differentiator
 
default_run_options[:pty] = true
 
# be sure to change these
set :user, 'app_user'
set :domain, 'urlunwind.com'
set :application, 'url_unwind'
set :git_path_prefix, "git@github.com/tobias/"
 
# the rest should be good
set :repository, "#{git_path_prefix}#{application}.git"
set :deploy_to, "/home/#{user}/#{domain}"
set :deploy_via, :remote_cache
set :scm, 'git'
set :branch, 'master'
#set :git_shallow_clone, 1
set :scm_verbose, true
set :use_sudo, false
 
server domain, :app, :web
 
namespace :deploy do
  task :restart do
    run "test -d #{current_path}/tmp || mkdir #{current_path}/tmp"
    run "test -d #{current_path}/log || mkdir #{current_path}/log"
    run "touch #{current_path}/tmp/restart.txt"
  end
end

Since the Sinatra gem is not installed on Dreamhost, I put it in vendor/ within the app. Since it is not a gem, it must be required with the full path to the base .rb file, both in config.ru and in the app file itself (urlunwind.rb in this case). Here is the final config.ru:

require 'rubygems'
require 'vendor/sinatra/lib/sinatra.rb'
 
disable :run
set :env, :production
set :raise_errors, true
set :views, File.dirname(__FILE__) + '/views'
set :public, File.dirname(__FILE__) + '/public'
set :app_file, __FILE__
 
log = File.new("log/sinatra.log", "a")
STDOUT.reopen(log)
STDERR.reopen(log)
 
require 'urlunwind.rb'
run Sinatra.application

I’ve also been trying to learn some new things and improve on some things I already kind of know. Last week I built a rails app from scratch, testing all the way. It was nice to truly be the boss of the project and call all of the shots. It was also nice to get back to basics with Test::Unit and do TDD from the start. It was nice to build most of the application without hitting it with the browser; the context switch of switching from Emacs to FireFox wears me out sometimes, and I really dislike using the mouse when I’m coding. The app is a simple secret gift exchange name chooser, with a twist. You can play with it at HatFullOfNames.com.

Last night and today I built an app using Sinatra, the lightweight Ruby web framework that is all the rage with the kids these days. It was a fun adventure – most of my Ruby experience so far has been within the Rails bubble. I plan to write a couple of posts about the experience – one covering working with Sinatra, the second covering deploying a Sinatra app to Passenger on shared hosting (Dreamhost in this case). This app is a short url unwinder, allowing you to see the destination of a short url before clicking on it. It also provides a web service to handle the lookups that returns JSON. Use it at URLUnwind.com.

I’ll get started on that Sinatra post right now…