RubyOnRails DotCloud Rails setup

_readme.md

Description of current setup

Initially, I was using only postinstall to do migrations and assets precompilation.

At some point though, since the precompilation is super slow, I had time outs when pushing.

Based on advice by Andy (I think), I moved stuff to postbuild.

Faced to the need of running migrations, I decided to attempt detecting instance 0 to only run those on one machine (and it worked fine).

Similarly, I deployed the cron jobs only on one instance.

For cron I had to hardcode the path to rvm wrappers.

For database connection: Rails evaluates database.yml via ERB, so I built a little dot_cloud.rb configuration helper to grab the data from the environment file.

Things would have been definitely easier here if the variables had been exposed as real environment variables.

Post deploy, I launch ab to make sure all the passenger are immediately fired up and avoid delays for the end-user.

Things to improve for the advanced user:

• I'd like to go even further and hope to use the latest "live" deploy protocol to have absolutely zero downtime if I can (tips welcome!)
• assets precompilation is very, very slow on instances (much faster locally, but it's much more convenient to not have to check the files in git) - anything to fasten that will be welcome (replacing therubyracer by something else etc... unsure)

crontab

MAILTO="[email protected]"
PATH=/usr/local/rvm/wrappers/ruby-1.9.2-p136@dotcloud:/usr/local/rvm/gems/ruby-1.9.2-p136@dotcloud/bin:/usr/local/rvm/gems/ruby-1.9.2-p136@global/bin:/usr/local/rvm/rubies/ruby-1.9.2-p136/bin:/usr/local/rvm/bin:/usr/local/bin:/usr/local/sbin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/lib/jvm/java-6-sun/bin
GEM_HOME=/usr/local/rvm/gems/ruby-1.9.2-p136@dotcloud
RAILS_ENV=production

0 1 * * * cd ~/current && rake your_task

database.dotcloud.yml

<%
  require 'dot_cloud'
  database = DotCloud.staging? ? 'myappstaging' : 'myapp'
  yaml = DotCloud.config
%>

production:
  adapter: postgresql
  encoding: unicode
  database: <%= database %>
  username: <%= database %>
  password: <%= yaml['MYAPP_DB_SQL_PASSWORD'] %>
  pool: 5
  host: <%= yaml['DOTCLOUD_DB_SQL_HOST'] %>
  port: <%= yaml['DOTCLOUD_DB_SQL_PORT'] %>

deploy_and_wake.sh

#!/bin/sh
set -e
echo Backing up...
./backup
echo Deploying...
dotcloud push --application myapp --git
echo Waking up!!! (make sure all passenger instances are touched)
ab -n 10 -c 3 https://www.myapp.com/

dot_cloud.rb

require 'yaml'

module DotCloud
  def self.config
    @yaml ||= YAML.load(IO.read('/home/dotcloud/environment.yml'))
  end

  def self.staging?
    case config['DOTCLOUD_PROJECT']
      when 'myappstaging'; true
      when 'myapp'; false
      else raise "Unsupported dotcloud app"
    end
  end

  # examples of setters
  def self.smtp_username
    config['MYAPP_SMTP_USERNAME']
  end

  def self.smtp_password
    config['MYAPP_SMTP_PASSWORD']
  end
end

dotcloud.yml

www:
  type: ruby
  config:
     ruby-version: 1.9.2
  exclude_bundler_groups:
    - development
    - test
  postbuild: ./postbuild
db:
  xxx:

Gemfile

source 'http://rubygems.org'

gem 'rails', '3.2.x'

# Gems used only for assets and not required
# in production environments by default.
group :assets do
  gem 'sass-rails', "3.2.5"
  gem 'coffee-rails', "3.2.2"
  gem 'uglifier', '1.2.4'
  gem 'twitter-bootstrap-rails'
end

# ...

group :dotcloud do
  # DotCloud does not provide a js runtime today - add one
  gem 'therubyracer'
end

postbuild

#!/bin/sh
set -e

echo ====== postbuild starting =======
echo Currently in folder `pwd`
cp config/database.dotcloud.yml config/database.yml
echo ====== precompiling assets ===========
rake assets:precompile RAILS_ENV=production
echo ====== postbuild done =========

postinstall

#!/bin/sh
set -e

echo ===== postinstall starting =====
service_id=$(ruby -e "require 'json'; env = JSON.parse(File.read('/home/dotcloud/environment.json')); puts env['DOTCLOUD_SERVICE_ID']")
if [ "$service_id" = "0" ]
then
  echo ====== migrating db + installing crontab ==========
  # TODO - allow to pass a variable to only run migrate if necessary to speed things up
  # rake db:migrate cron:verify cron:install RAILS_ENV=production
  rake cron:verify cron:install RAILS_ENV=production
fi
echo ====== postinstall done! =======

scheduler.rake

def system!(cmd)
  raise "Cannot run command!!!" unless system(cmd)
end

namespace :cron do

  desc "Verify ruby version expected by cron jobs"
  task :verify => :environment do
    # safeguard since I hardcoded the ruby path in crontab
    raise "Ruby version changed!" unless `ruby -v` =~ /ruby 1.9.2p136/
  end

  desc "Install the cron jobs (except on staging)"
  task :install => :environment do
    if DotCloud.staging?
      # avoid sending emails in staging etc
      puts "Cron jobs not installed - staging server"
    else
      system!("crontab #{Rails.root.join('config', 'crontab')}")
    end
  end

end