Create a software RAID set on macOS

appleraid.rb

#!/usr/bin/env ruby
# coding: utf-8

abort "This script needs Ruby 2 or later. You have #{RUBY_VERSION}." if RUBY_VERSION < '2.0.0'

require 'io/console'
require 'pathname'
require 'shellwords'

# Imitating ActiveSupport a bit here:
class String
  def blank?
    strip == ''
  end
end

class Object
  def blank?
    !!self
  end

  def present?
    !blank?
  end
end

STDIN.reopen('/dev/tty') unless STDIN.isatty # So this script can be piped into Ruby

class Disk < Hash
  attr_accessor :selected
  attr_reader :device_name

  def initialize(device_name)
    @device_name = device_name
    merge! `diskutil info #{device_name}`.scan(/^\s*(.+?):\s+(.+?)\s*$/).to_h
  end

  def raidable?
    !(virtual? || internal?)
  end

  def virtual?
    self['Virtual'] == 'Yes'
  end

  def internal?
    self['Device Location'] == 'Internal'
  end

  def description
    @name ||= (
      n = self['Volume Name']
      n = self['Device / Media Name'] if n.start_with? 'Not applicable'
      n
    )
  end

  # def byte_size
  #   @byte_size ||= self['Disk Size'][/\((\d+) Bytes\)/, 1].to_i
  # end

  def human_size
    @human_size ||= (self['Total Size'] || self['Disk Size'])[/^(.+?)\s*\(/, 1]
  end

  def toggle!
    self.selected = !selected
  end

  class << self
    attr_accessor :cursor, :chosen

    def all
      @all ||= Dir['/dev/disk?'].map { |n| Disk.new n[/\w+$/] }.select(&:raidable?)
    end

    def show!
      puts "\e[A" * (all.length + 5) if @shown
      all.map.with_index do |disk, index|
        puts [
            index == cursor ? '➤ ' : '  ',
            disk.selected ? '✓' : ' ',
            disk.human_size,
            disk.description
        ].join ' '
      end
      puts ''
      puts 'UP / DOWN  to move cursor'
      puts 'SPACE      to toggle'
      puts 'ENTER      to continue'
      @shown = true
    end

    def move(offset)
      self.cursor = (cursor + offset) % all.length
      show!
    end

    def toggle!
      all[cursor].toggle!
      show!
    end

    def choose!
      self.chosen = all.select(&:selected)
    end
  end

  self.cursor = 0
end

# Borrowed from https://gist.github.com/acook/4190379
def read_char
  STDIN.echo = false
  STDIN.raw!

  input = STDIN.getc.chr
  if input == "\e"
    input << STDIN.read_nonblock(3) rescue nil
    input << STDIN.read_nonblock(2) rescue nil
  end
ensure
  STDIN.echo = true
  STDIN.cooked!

  return input
end

# Borrowed from Captain
def prompt(str, silent = false, default: nil)
  print str
  result = silent ? STDIN.noecho(&:gets) : STDIN.gets
  puts '' if silent || result.nil? || !result.end_with?($/)
  result = (result || '').chomp
  result = default if result.blank? && default.present?
  result = yield(result) if block_given?
  result
end

# Borrowed from Captain
def choose(text, letters)
  chars   = letters.chars.map(&:downcase).uniq
  default = letters.chars.find { |c| c.upcase == c }
  default = default.downcase if default

  print "#{text} [#{letters}]: "
  result = nil
  while result.nil?
    result = STDIN.getch.downcase
    print result = default if result == "\r" || result == "\n"
    result = nil unless chars.include? result
  end
  puts ''
  result
end

puts "Create a new AppleRAID volume (PID #{$$})"
puts ''
puts 'Choose two or more volumes to continue;'
puts ''

Disk.show!

until Disk.chosen do
  case read_char
    when "\e[A"
      Disk.move -1
    when "\e[B"
      Disk.move 1
    when ' '
      Disk.toggle!
    when "\r"
      Disk.choose!
    when "\e", "\x03" # Escape or CTRL+C
      exit 1
    else
      print "\x07" # Alarm
  end
end

abort 'You need to choose at least two disks.' unless Disk.chosen.length >= 2

puts ''
scheme = {
    s: 'stripe',
    m: 'mirror',
    c: 'concat'
}[choose('Do you want Striped, Mirrored, or Concatenated?', 'smc').to_sym]

name = prompt('Enter a name for your RAID volume: ', default: 'New RAID Volume', &:strip)

puts ''

cmd = ['diskutil', 'appleRAID', 'create', scheme, name, 'JHFS+', *Disk.chosen.map(&:device_name)]

puts 'This is the command you need to run:'
puts ''
puts cmd.map(&:shellescape).join ' '
puts
system *cmd if choose('Do you want me to run it for you?', 'Yn') == 'y'