rake task to generate version.rb file from git metadata

version_task.rb

require 'fileutils'
require 'bundler/gem_tasks'
require 'git'

  def gen_version_file(version, build, filename)
  data = []
  data << "# --- GENERATED BY RAKE. DON'T MODIFY"
  data << 'module Patugo::Search'
  data << "  VERSION = '#{version}'"
  data << "  BUILD = '#{build}'"
  data << "end"
  data << ""
  File.open filename, 'w' do |f|
    f.syswrite data.join("\n")
    f.close
  end
end

namespace :patugo do
  VERSION_FILE = 'lib/patugo/version.rb'.freeze

  desc 'generate version.rb from git metadata'
  task :version_rb do
    g = Git.open '.'
    # get version and patch level from git tag
    version = g.describe.gsub(/^v(.+)-(.+)-.*/, '\1.\2')
    build = g.object('HEAD').sha[0, 7]
    gen_version_file version, build, VERSION_FILE
  end
end