Gitにリリースタグを打つRakeタスク ref: http://qiita.com/piyo7/items/eee68999d5f74a2266ce

file0.txt

require "open3"
require "time"

task :add_release_tag do
  day = Time.now.strftime("%Y%m%d")
  ver = 0
  tag = "#{day}.#{ver}"
  while Open3.capture3("git show #{tag}")[2].exitstatus == 0
    ver += 1
    tag = "#{day}.#{ver}"
  end

  `git tag -a #{tag} -m "release tag by rake"`
  `git push #{ENV["REMOTE_REPOGITORY"]} --tags`
end

file1.txt

task :release => [:prepare, :deploy, :add_release_tag]