Capistrano + Rails + Unicorn + NGinx + RVM

Capistrano is a ruby based deployment tool which executes commands in parallel on multiple remote machines, via the SSH protocol. With Capistrano you can deploy your application on N server with one single command from your dev machine. You don’t need to login via SSH to your server.

Screen Shot 2013-01-15 at 8.15.33 PM

If you don’t deploy your app on Heroku or CloudControl, if you have dedicated servers or you are using AWS, than Capistrano is the way to go.

Before you start with Capistrano, you have to implement SSH with authentification keys instead of password. In that way you can just login to your server with a simple “ssh user@server” without password. That is possible if your public ssh certificates are on the server. In that way the server “knows” you.

First you need to add the Gem to your Gemfile.

gem 'capistrano'
gem 'rvm-capistrano'

I am adding here “rvm-capistraon”, too. Because I am working with RVM on my dev machine and on the server. Now you have to run bundler.

bundle install

As next step you have to capify your rails project. Just run:

capify .

That will create some files in your project.

[add] writing './Capfile'
[add] writing './config/deploy.rb'
[done] capified!

Your Capfile is loading the deploy.rb script. The Capfile should look like this:

load 'deploy'
# Uncomment if you are using Rails' asset pipeline
# load 'deploy/assets'
load 'config/deploy'

The magic happens in the deploy.rb file. The full documentation to this script you will find here: https://github.com/capistrano/capistrano. It basically executes a couple of commands on your server. It fetches the current code from your GIT server, runs bundler, rake db:migrate, precompiles your assets and runs the ruby app server.

Here is my deploy.rb with some additional comments.


# Automatically precompile assets
load "deploy/assets"

# Execute "bundle install" after deploy, but only when really needed
require "bundler/capistrano"

# RVM integration
require "rvm/capistrano"

# Name of the application in scm (GIT)
set :application, "your_app"
set :repository, "git@github.com:your_company/your_project/project.git"

# Source Control Management
set :scm, :git

set :deploy_to, "/var/www/#{application}"

# server there the web server is running (nginx)
role :web, "192.168.0.12"

# server there the app server is running (unicorn)
role :app, "192.168.0.12"

# server there the db is running
# This is where Rails migrations will run
role :db, "192.168.0.12", :primary => true

set :rails_env, :production

# user on the server
set :user, "project_user"
set :use_sudo, false

# Target ruby version
set :rvm_ruby_string, '1.9.3'

# System-wide RVM installation
set :rvm_type, :system

# Apply default RVM version for the current account
after "deploy:setup", "deploy:set_rvm_version"

namespace :deploy do

  task :set_rvm_version, :roles => :app, :except => { :no_release => true } do
    run "source /etc/profile.d/rvm.sh && rvm use #{rvm_ruby_string} --default"
  end

  task :start, :roles => :app, :except => { :no_release => true } do
    run "/etc/init.d/unicorn start"
  end

  task :stop, :roles => :app, :except => { :no_release => true } do
    run "/etc/init.d/unicorn stop"
  end

  task :restart, :roles => :app, :except => { :no_release => true } do
    run "/etc/init.d/unicorn restart"
  end

  # Precompile assets
  namespace :assets do
    task :precompile, :roles => :web, :except => { :no_release => true } do
      run %Q{cd #{latest_release} && #{rake} RAILS_ENV=#{rails_env} #{asset_env} assets:precompile}
    end
  end

end

The script for starting and stoping unicorn you can find here: https://robert-reiz.com/2012/02/29/running-unicorn-as-a-service-on-debian-linux/.

On the Linux server you should install a couple things before you deploy:

apt-get install make
apt-get install g++
gem update --system
gem install bundler

Now you can deploy with:

cap deploy

And this command shows you all possible Capistrano tasks:

cap -T

Let me know if you have questions.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s