run_ruby_with_bundler_and_rvm.rb

#!/usr/bin/env ruby
# Given an absolute path to a ruby file and an optional RVM directory, locates
# both an `.rvmrc` and a `Gemfile` and runs the script with both.

script     = ARGV.shift
$rvm_path  = ARGV.shift.to_s
rvm_script = "#{$rvm_path}/scripts/rvm"
$rvm_path  = nil unless File.exists?(rvm_script)
bundler    = nil

def locate_rvmrc
  dir = '.'
  while (dir = File.expand_path(dir)) != '/' do
    rvmrc = File.join(dir, ".rvmrc")
    if File.exists?(rvmrc)
      return rvmrc
    end
    dir = File.join dir, '..'
  end
  nil
end

def run_ruby(cmd, exec = false)
  raise unless $ruby_cmd.length > 0

  cmd = "bash -c '#{$ruby_cmd} #{cmd}'"
  if exec
    exec(cmd)
  else
    out = `#{cmd}`
    [$?.exitstatus == 0, out]
  end
end

cwd = File.dirname(script)
Dir.chdir(cwd) do
  rvmrc = locate_rvmrc if $rvm_path
  $ruby_cmd = if rvmrc
    "export rvm_path=#{$rvm_path}; source #{rvm_script}; source #{rvmrc}; ruby"
  else
    "/usr/bin/ruby"
  end

  if !run_ruby("-S bundle --help")[0]
    bundler = false
  else
    success, out = run_ruby("-S bundle check --no-color")
    if success
      bundler = true
    else
      if out =~ /Could not locate Gemfile/
        bundler = false
      else
        success, out = run_ruby("-S bundle --no-color")
        if success
          bundler = true
        else
          $stderr.puts out
          exit 1
        end
      end
    end
  end

  cmd = if bundler
    "-S bundle exec ruby"
  else
    ""
  end
  cmd += " " + script
  puts cmd
  run_ruby(cmd, true)
end