Deploy 12-Factor Apps with Capistrano::Buildpack

Last month I wrote a short article describing a method of deploying a 12-factor application application to your own hardware or VPS, outside of Heroku. Today I'm happy to announce a gem named capistrano-buildpack which packages up and formalizes this deployment method.

Basically, all this does is wrap up the before and after hooks that the other article talks about, which lets you set up a Capfile that looks like this:

require 'rubygems'

set :application, "bugsplatdotinfo"
set :repository, "https://github.com/peterkeen/bugsplat.rb"
set :scm, :git
set :additional_domains, ['bugsplat.info']

role :web, "examplevps.bugsplat.info"
set :buildpack_url, "https://github.com/peterkeen/bugsplat-buildpack-ruby-simple"

set :user, "peter"
set :base_port, 6700
set :concurrency, "web=1"

set :deploy_env, {
  'LANG' => 'en_US.UTF-8',
  'PATH' => 'bin:vendor/bundle/ruby/1.9.1/bin:/usr/local/bin:/usr/bin:/bin',
  'GEM_PATH' => 'vendor/bundle/ruby/1.9.1:.',
  'RACK_ENV' => 'production',
}

load 'deploy'
require 'capistrano-buildpack'

This sets up the standard boilerplate Capistrano variables and roles, as well as :buildpack_url which controlls which buildpack to clone/update, as well as :base_port, :concurrency, and :deploy_env which tell foreman and foreman-export-nginx what to do. When you run cap deploy with this Capfile, these steps happen:

• Clone/update the buildpack
• Clone/update the code repository
• Apply the buildpack to the code repository
• Create upstart-style init files in /etc/init and start up the app
• Create an nginx config file at `/etc/nginx/conf.d/.conf and restart nginx

The nginx config will set up one default hostname, <application>.<deploy host>, as well as list out the additional domains specified in the :additional_domains setting. Make sure to set up your DNS properly for these hostnames.

capistrano-buildpack defaults to deploying apps to /apps/<application>, nginx configs to /etc/nginx/conf.d, upstart files to /etc/init, and logs to /var/log/apps/<application>-*.log. Everything except the log path can be customized by setting these vars:

set :deploy_to, "/your/path/#{application}"
set :foreman_export_path, "/your/init/path"
set :nginx_export_path, "/your/nginx/conf/path"
set :foreman_export_type, "runit_or_whatever"

Right now Capistrano::Buildpack will attempt to run sudo service <application> restart when running services. This may not be appropriate for all environments. If you want to generalizethis, please submit a pull request and I'll merge it.