deploy.rb

set :staging_database,    "app_name_staging"
set :staging_dbhost,      "mysql50-staging-1"
set :production_database,    "app_name_production"
set :production_dbhost,      "mysql50-production-1"

task :staging do
  role :web, "1.2.3.4"
  role :app, "1.2.3.4"
  role :db , "1.2.3.4", :primary => true

  set :rails_env, "staging"
  set :environment_database, defer { staging_database }
  set :environment_dbhost, defer { staging_dbhost }
end

task :production do
  role :web, "1.2.3.5"
  role :app, "1.2.3.5"
  role :db , "1.2.3.5", :primary => true

  set :rails_env, "production"
  set :environment_database, defer { production_database }
  set :environment_dbhost, defer { production_dbhost }
end