Restarting Unicorn Synchronously

unicorn_restart.rb

#!/usr/bin/env ruby
require "optparse"

def usage
  STDERR.puts "usage: #{$0} /path/to/unicorn.pid [-t timeout_sec]"
end

timeout = 60

pidfile = ARGV.shift
unless pidfile
  usage
  exit 1
end
unless File.exist?(pidfile)
  STDERR.puts "PID file doesn't exist: #{pidfile}"
  exit 1
end

opt = OptionParser.new(ARGV)
opt.on("-t timeout_sec") {|t| timeout = t.to_i }
opt.parse!

oldbin = "#{pidfile}.oldbin"
old_pid = open(pidfile).read.to_i
new_pid = nil

if File.exist?(oldbin)
  STDERR.puts "Still restarting"
  exit 1
else
  Process.kill :USR2, old_pid
end

print "Restarting Unicorn"
STDOUT.flush

timeout_count = 0
loop do
  if timeout_count > timeout
    STDERR.puts "Timeout"
    exit 1
  end

  if new_pid
    if File.exist?(oldbin)
      print '.'
      STDOUT.flush
    else
      if open(pidfile).read.to_i == old_pid
        puts "Failure"
      else
        puts "Success"
      end
      break
    end
  else
    if File.exist?(pidfile)
      new_pid = open(pidfile).read.to_i
    end
  end
  sleep 1
  timeout_count += 1
end