Hacking an erlang application deployment with Capistrano 3

Capfile

# Load DSL and Setup Up Stages
require 'capistrano/setup'

# Includes default deployment tasks
require 'capistrano/deploy'

# Loads custom tasks from `lib/capistrano/tasks' if you have any defined.
Dir.glob('lib/capistrano/tasks/*.cap').each { |r| import r }

namespace :deploy do

  task :build do
    on roles(:app) do
      within release_path do
        execute :make
      end
    end
  end

  task :upstart_config do
    on roles(:app) do
      user = capture :whoami
      config = "\
start on starting manas
stop on stopping manas
respawn
chdir #{current_path}
setuid #{user}
env HOME=#{current_path}

exec erl -pa ebin deps/*/ebin -boot start_sasl -s manas_service_app -config manas_service -noshell -noinput >> /var/log/manas/service.log 2>&1
"
      sudo %(sh -c "echo \\"#{config.gsub("\n", "\\n")}\\" > /etc/init/service.conf")
    end
  end

  desc 'Restart application'
  task :restart do
    on roles(:app), in: :sequence, wait: 5 do
      sudo "stop service || true"
      sudo "start service"
    end
  end

  after :restart, :clear_cache do
    on roles(:web), in: :groups, limit: 3, wait: 10 do
    end
  end

  after :finishing, 'deploy:cleanup'

  before :publishing, 'deploy:build'
  before :publishing, 'deploy:upstart_config'
end