Capistrano task to push a deploy tag after deploying a new version.

ask_for_branch.rb

set(:branch) do
  if :production == stage
    branch = Capistrano::CLI.ui.ask("#{`git branch`}\n\nWhich branch do you want to deploy?: ")
    raise "Error: The master branch cannot be deployed to production." if 'master' == branch
  else
    `git branch | grep ^* | sed s/\\*\\ //`.chomp # use current active branch for staging
  end
end

capistrano_git.rb

namespace :deploy do
  after  "deploy:restart", "deploy:git:push_deploy_tag"
  before "deploy:cleanup", "deploy:git:cleanup_deploy_tag"

  namespace :git do

    desc "Place release tag into Git and push it to server."
    task :push_deploy_tag do
      puts `git push origin tag #{rails_env}/#{release_name} #{revision}`
    end

    desc "Place release tag into Git and push it to server."
    task :cleanup_deploy_tag do
      count = fetch(:keep_releases, 5).to_i
      if count >= releases.length
        logger.important "no old release tags to clean up"
      else
        logger.info "keeping #{count} of #{releases.length} release tags"

        tags = (releases - releases.last(count)).map { |release| "#{rails_env}/#{release}" }

        tags.each do |tag|
          `git push origin :refs/tags/#{tag}`
        end
      end
    end
  end
end