unicorn.rb

app_name = "ldl-website"
root = "/var/www/#{app_name}/current"

pid           "#{root}/tmp/pids/unicorn.pid"
stderr_path   "#{root}/log/unicorn.error.log"
stdout_path   "#{root}/log/unicorn.access.log"

listen "/tmp/unicorn.#{app_name}.sock", :backlog => 2048

preload_app true
working_directory root
worker_processes 2
timeout 30

before_fork do |server, worker|
  # the following is highly recomended for Rails + "preload_app true"
  # as there's no need for the master process to hold a connection
  defined?(ActiveRecord::Base) and ActiveRecord::Base.connection.disconnect!

  ##
  # When sent a USR2, Unicorn will suffix its pidfile with .oldbin and
  # immediately start loading up a new version of itself (loaded with a new
  # version of our app). When this new Unicorn is completely loaded
  # it will begin spawning workers. The first worker spawned will check to
  # see if an .oldbin pidfile exists. If so, this means we've just booted up
  # a new Unicorn and need to tell the old one that it can now die. To do so
  # we send it a QUIT.
  #
  # Using this method we get 0 downtime deploys.

  old_pid = "#{root}/tmp/pids/unicorn.pid.oldbin"
  if File.exists?(old_pid) && server.pid != old_pid
    begin
      Process.kill("QUIT", File.read(old_pid).to_i)
    rescue Errno::ENOENT, Errno::ESRCH
      # someone else did our job for us
    end
  end
end

after_fork do |server, worker|
  ##
  # Unicorn master loads the app then forks off workers - because of the way
  # Unix forking works, we need to make sure we aren't using any of the parent's
  # sockets, e.g. db connection

  defined?(ActiveRecord::Base) and ActiveRecord::Base.establish_connection
  # Redis and Memcached would go here but their connections are established
  # on demand, so the master never opens a socket

  ##
  # Unicorn master is started as root, which is fine, but let's
  # drop the workers to deployer:deployer

  begin
    uid, gid = Process.euid, Process.egid
    user, group = 'deployer', 'deployer'
    target_uid = Etc.getpwnam(user).uid
    target_gid = Etc.getgrnam(group).gid
    # worker.tmp.chown(target_uid, target_gid)
    if uid != target_uid || gid != target_gid
      Process.initgroups(user, target_gid)
      Process::GID.change_privilege(target_gid)
      Process::UID.change_privilege(target_uid)
    end
  rescue => e
    if RAILS_ENV == 'development'
      STDERR.puts "couldn't change user, oh well"
    else
      raise e
    end
  end
end

unicorn.sh

#!/bin/sh
### BEGIN INIT INFO
# Provides:          unicorn
# Required-Start:    $remote_fs $syslog
# Required-Stop:     $remote_fs $syslog
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Manage unicorn server
# Description:       Start, stop, restart unicorn server for a specific application.
### END INIT INFO
set -e

# Feel free to change any of the following variables for your app:
export RUBY_GC_HEAP_MIN_SLOTS=800000
export RUBY_GC_HEAP_SLOTS_INCREMENT=250000
export RUBY_GC_HEAP_SLOTS_GROWTH_FACTOR=1
export RUBY_GC_MALLOC_LIMIT=50000000

TIMEOUT=${TIMEOUT-60}
APP_ROOT=/var/www/ldl-website/current
PID=$APP_ROOT/tmp/pids/unicorn.pid
CMD="cd $APP_ROOT && ~/.rbenv/bin/rbenv exec bundle exec unicorn -D -c $APP_ROOT/config/unicorn.rb -E staging"
AS_USER=deployer
set -u

OLD_PIN="$PID.oldbin"

sig () {
  test -s "$PID" && kill -s $1 `cat $PID`
}

run () {
  if [ "$(id -un)" = "$AS_USER" ]; then
    eval $1
  else
    su -c "$1" - $AS_USER
  fi
}

case "$1" in
start)
  sig 0 && echo >&2 "Already running" && exit 0
  run "$CMD"
  ;;
stop)
  sig QUIT && exit 0
  echo >&2 "Not running"
  ;;
force-stop)
  sig TERM && exit 0
  echo >&2 "Not running"
  ;;
restart|reload)
  sig HUP && echo reloaded OK && exit 0
  echo >&2 "Couldn't reload, starting '$CMD' instead"
  run "$CMD"
  ;;
upgrade)
  if sig USR2 && sleep 3
  then
    n=$TIMEOUT
    while test -s $OLD_PIN && test $n -ge 0
    do
      printf '.' && sleep 1 && n=$(( $n - 1 ))
    done
    echo

    if test $n -lt 0 && test -s $OLD_PIN
    then
      echo >&2 "$OLD_PIN still exists after $TIMEOUT seconds"
      exit 1
    fi
    exit 0
  fi
  echo >&2 "Couldn't upgrade, starting '$CMD' instead"
  run "$CMD"
  ;;
reopen-logs)
  sig USR1
  ;;
*)
  echo >&2 "Usage: $0 <start|stop|restart|upgrade|force-stop|reopen-logs>"
  exit 1
  ;;
esac