Check for pending migrations on Heroku. Useful after a deploy.

heroku_check_pending_migration.rb

  # git_remote_name: git remote name associated with your heroku repository (usually "heroku")
    def pending_migrations?(git_remote_name)
      command = "heroku run rails runner \"puts ActiveRecord::Migrator.needs_migration?\" --remote #{git_remote_name}"
      output = `#{command}`
      output_last_line = output.split("\n").last
      raise 'Could not check migration status' unless output_last_line.in? %w(true false)
      output_last_line == 'true'
    end