create a tag.txt file that contains details about the last commit which was deployed to a particular environment.

deploy.rb

  after "deploy:update_code", "deploy:create_tagfile"

  desc "Create a tagfile with the latest tag and commit that was deployed."
  task :create_tagfile, :roles => :app do
    tagfile = "#{current_release}/public/tag.txt"
    run "touch #{tagfile}"
    run "cd #{current_release}; echo `git describe --tags` >> #{tagfile};"
    run "cd #{current_release}; git log -n 1 >> #{tagfile};"
  end