node upstart deploy example

deploy.rb

set :stages, %w(production demo staging)
set :default_stage, "staging"
require "capistrano/ext/multistage"

set :application, "example-app"

set :repository,  "[email protected]"
set :branch, "master"
set :scm, :git
set :git_enable_submodules, 1

set :admin_user, "ubuntu"
set :user, "app"
set :use_sudo, false
set :deploy_to, "/home/#{user}/#{application}"
set :deploy_via, :remote_cache

ssh_options[:forward_agent] = true
# pty return yes if host is first time added
default_run_options[:pty]   = true



after "deploy:update_code", "deploy:npm_install"
after "deploy:update_code", "deploy:link_config"
after 'deploy:update_code', "deploy:write_upstart_script"

def with_user(new_user, &block)
  old_user = user
  set :user, new_user
  close_sessions
  yield
  set :user, old_user
  close_sessions
end

def upstart_script
<<-UPSTART_SCRIPT
description "#{application} upstart script"
start on startup
stop on shutdown
console output
respawn
respawn limit 5 60
script
  exec su #{user} -c `cd #{release_path} && NODE_ENV=#{stage} node #{release_path}/server.js >> #{release_path}/log/production.log 2>&1`
end script

post-start script
  PID=`status #{application} | egrep -oi '([0-9]+)$' | head -n1`
  su #{user} -c `echo $PID > #{release_path}/tmp/pids/#{application}.pid`
end script

post-stop script
  su #{user} -c `rm -f #{release_path}/tmp/pids/#{application}.pid`
end script
UPSTART_SCRIPT
end

def close_sessions
  sessions.values.each { |session| session.close }
  sessions.clear
end

namespace :deploy do
  task :start, :roles => :app do
    with_user(admin_user) { run "sudo restart #{application} || sudo start #{application}" }
  end

  task :stop, :roles => :app do
    with_user(admin_user) { run "sudo stop #{application}" }
  end

  task :restart, :roles => :app do
    start
  end

  task :npm_install do
    run "mkdir -p #{shared_path}/npm"
    run "cp #{release_path}/package.json #{shared_path}/npm/package.json"
    run "cp #{release_path}/npm-shrinkwrap.json #{shared_path}/npm/npm-shrinkwrap.json"
    run "cd #{shared_path}/npm && npm install"
    run "ln -s #{shared_path}/npm/node_modules #{release_path}/node_modules"
  end

  task :link_config do
    run "ln -s #{shared_path}/config.json #{release_path}/config/config.json"
  end

  task :write_upstart_script, :roles => :app do
    put upstart_script(), "#{release_path}/#{application}.conf"
    with_user admin_user do
      sudo "mv #{release_path}/#{application}.conf /etc/init"
    end
  end
end