docs: def backup_db(release=None, limit=5):
      """
      Backup database and associate it with current release
      """
  
      assert "mysql_user" in env, "Missing mysqL_user in env"
      assert "mysql_password" in env, "Missing mysql_password in env"
      assert "mysql_host" in env, "Missing mysql_host in env"
      assert "mysql_db" in env, "Missing mysql_db in env"
  
      if not release:
          release = paths.get_current_release_name()
  
      max_versions = limit+1
  
      if not release:
          return
  
      env.run("mkdir -p %s" % paths.get_backup_path("mysql"))
  
      backup_file = "mysql/%s.sql.gz" % release
      backup_path = paths.get_backup_path(backup_file)
  
      env.run("mysqldump -u %s -p%s -h %s %s | gzip -c > %s" %
              (env.mysql_user, env.mysql_password, env.mysql_host, env.mysql_db,
               backup_path))
  
      # Remove older releases
      env.run("ls -dt %s/* | tail -n +%s | xargs rm -rf" % (
          paths.get_backup_path("mysql"),
          max_versions)
      )