Ruby on Rails: Automatically push changes to Git repository before deploying with Capistrano (cap deploy)

deploy.rb

# I use this Capistrano task so I don't have manually run 'git push' before 'cap
# deploy'. It includes some error checking to make sure I'm on the right branch
# (master) and haven't got any uncommitted changes.

# Simply add the code below to config/deploy.rb, then run 'cap deploy:push' to
# test it, and 'cap deploy' to deploy as usual.

namespace :deploy do
  desc "Push local changes to Git repository"
  task :push do

    # Check for any local changes that haven't been committed
    # Use 'cap deploy:push IGNORE_DEPLOY_RB=1' to ignore changes to this file (for testing)
    status = %x(git status --porcelain).chomp
    if status != ""
      if status !~ %r{^[M ][M ] config/deploy.rb$}
        abort "Local git repository has uncommitted changes"
      elsif !ENV["IGNORE_DEPLOY_RB"]
        # This is used for testing changes to this script without committing them first
        abort "Local git repository has uncommitted changes (set IGNORE_DEPLOY_RB=1 to ignore changes to deploy.rb)"
      end
    end

    # Check we are on the master branch, so we can't forget to merge before deploying
    branch = %x(git branch --no-color 2>/dev/null | sed -e '/^[^*]/d' -e 's/* \\(.*\\)/\\1/').chomp
    if branch != "master" && !ENV["IGNORE_BRANCH"]
      abort "Not on master branch (set IGNORE_BRANCH=1 to ignore)"
    end

    # Push the changes
    if ! system "git push #{fetch(:repository)} master"
      abort "Failed to push changes to #{fetch(:repository)}"
    end

  end
end

if !ENV["NO_PUSH"]
  before "deploy", "deploy:push"
  before "deploy:migrations", "deploy:push"
end