Stripping down Rails 3.1: Using only the database migrations

db.rb

tasks = [:create, :drop, :migrate, :rollback, :version, :seed, :setup]
tasks.each do |name|
  task name do
    sh "rake db:#{name.to_s} RAILS_ENV={environment}"
  end
end

Gemfile

source 'http://rubygems.org'
gem 'git-deploy'

gemfile = File.open(File.join(File.dirname(__FILE__), 'deploy', 'Gemfile'))
eval gemfile.read

new_rails.sh

rails new deploy

Rakefile

rakefile = File.open(File.join(File.dirname(__FILE__), 'deploy', 'Rakefile'))
eval rakefile.read.gsub(/config/, 'deploy/config')

task :generate do
  arguments = ARGV.find { |a| a.start_with?('GENERATE=') }
  arguments = arguments.split('=')[1] unless arguments.nil?
  sh "cd deploy; rails generate #{arguments}" unless arguments.nil? or arguments.empty?
end

db_tasks_file = File.open(File.join(File.dirname(__FILE__), 'deploy', 'lib', 'tasks', 'db.rb'))
db_tasks = db_tasks_file.read
namespace :db do
  namespaces = [:test, :production]
  namespaces.each do |name|
    namespace name do
      eval db_tasks.gsub(/{environment}/, name.to_s)
    end
  end
end