```ruby
# perform a deploy
#
class Heroku::Command::Deploy < Heroku::Command::Base
  # deploy
  #
  # deploy a ref (usually, the current HEAD)
  #
  # -m, --migrate  # run migrations after deploy
  #
  def index
    push && pushed
  end

  private

  # Push

  def push
    system(%{git push -f #{app} #{branch}:master})
  end

  def pushed
    migrate
  end

  # Migrations

  def migrate
    with_maintenance {
      run_command 'run', %w(rake db:migrate)
      run_command 'restart'
    } if migrate?
  end

  def migrate?
    options[:migrate]
  end

  # Utils

  def branch
    `git symbolic-ref HEAD`.strip.tap do
      raise 'Failed to get current branch name' unless $?.success?
    end
  end

  def run_command(name, args = [])
    Heroku::Command.run name, %W(--app #{app}).concat(args)
  end

  def with_maintenance
    run_command 'maintenance:on'

    yield

    run_command 'maintenance:off'
  end
end
```

Allow performing a backup before migrating.
user
```ruby
# perform a deploy
#
class Heroku::Command::Deploy < Heroku::Command::Base
  # deploy
  #
  # deploy a ref (usually, the current HEAD)
  #
  # -m, --migrate  # run migrations after deploy
  # -b, --backup   # perform a backup before migrating
  #
  def index
    push && pushed
  end

  private

  # Push

  def push
    system(%{git push -f #{app} #{branch}:master})
  end

  def pushed
    migrate
  end

  # Migrations

  def migrate
    with_maintenance {
      backup
      run_command 'run', %w(rake db:migrate)
      run_command 'restart'
    } if migrate?
  end

  def migrate?
    options[:migrate]
  end

  # Backup

  def backup
    run_command 'pgbackups:capture', %w(--expire)
  end

  def backup?
    options[:backup]
  end

  # Utils

  def branch
    `git symbolic-ref HEAD`.strip.tap do
      raise 'Failed to get current branch name' unless $?.success?
    end
  end

  def run_command(name, args = [])
    Heroku::Command.run name, %W(--app #{app}).concat(args)
  end

  def with_maintenance
    run_command 'maintenance:on'

    yield

    run_command 'maintenance:off'
  end
end
```
assistant