Convoluted&fragile precompile&deploy script

gistfile1.rb

namespace :deploy do

  desc 'Deploy a particular tag'
  task :tag, [:tag_name, :destination_remote] do |t, args|
    main_branch = %x[git symbolic-ref HEAD 2>/dev/null].split('/').last.strip
    tag_name = args[:tag_name]
    destination_remote = args[:destination_remote]
    destination_env = destination_remote.split('-').last
    cached_assets = "tmp/assets-#{destination_env}"

    puts "* Deploying tag #{tag_name} from main branch: #{main_branch} to #{destination_env}"

    puts "* Creating temp branch from tag: #{tag_name}..."
    puts ''
    %x[git checkout #{tag_name}]
    puts ''

    puts "* Using local asset cache for speed"
    %x[mv #{cached_assets} tmp/assets]
    puts ''

    puts "* Precompiling assets for rails environment '#{destination_env}'..."
    %x[RAILS_ENV=#{destination_env} rake assets:precompile --trace]
    puts ''

    puts "* Committing assets to local copy of tag..."
    %x[git add public/assets]
    %x[git commit public/assets -m"tmp local checkin for deploy"]
    puts ''

    dummy_tag = %x[git rev-parse HEAD 2>/dev/null].strip
    puts "* Deploying tag to Heroku with locally precompiled assets"
    git_cmd = "git push #{destination_remote} #{dummy_tag}:master --force"
    puts "* Doing: #{git_cmd}"
    %x[#{git_cmd}]
    puts ''

    puts "* Moving the cache to avoid cross-env issues..."
    %x[rm -rf #{cached_assets}]
    %x[mv tmp/assets #{cached_assets}]

    puts "* Switching back to your original main branch: #{main_branch}"
    %x[git checkout #{main_branch}]

  end

end