async function config(userId) {
  const CALDAV_URL = await this.gladys.variable.getValue('CALDAV_URL', this.serviceId, userId);
  const CALDAV_USERNAME = await this.gladys.variable.getValue('CALDAV_USERNAME', this.serviceId, userId);
  const CALDAV_PASSWORD = await this.gladys.variable.getValue('CALDAV_PASSWORD', this.serviceId, userId);

  if (!CALDAV_URL || !CALDAV_USERNAME || !CALDAV_PASSWORD) {
    throw new BadParameters('MISSING_PARAMETERS');
  }
  const xhr = new this.dav.transport.Basic(
    new this.dav.Credentials({
      username: CALDAV_USERNAME,
      password: CALDAV_PASSWORD,
    }),
  );

  // Get principal URL
  let req = this.dav.request.propfind({
    props: [{ name: 'current-user-principal', namespace: this.dav.ns.DAV }],
    depth: 0,
    mergeResponses: true,
  });

  let CALDAV_PRINCIPAL_URL;

  try {
    const {
      props: { currentUserPrincipal },
    } = await xhr.send(req, CALDAV_URL);
    CALDAV_PRINCIPAL_URL = url.resolve(CALDAV_URL, currentUserPrincipal);
  } catch (e) {
    logger.error(e);
    switch (e.message) {
      case 'Bad status: 401':
      case 'Bad status: 403':
        throw new BadParameters('CALDAV_BAD_USERNAME_PASSWORD');
      case 'Bad status: 404':
        throw new BadParameters('CALDAV_BAD_URL');
      default:
        throw new Error400('CALDAV_BAD_SETTINGS_PRINCIPAL_URL');
    }
  }

  logger.info(`CalDAV : Principal URL found: ${CALDAV_PRINCIPAL_URL}`);
  await this.gladys.variable.setValue('CALDAV_PRINCIPAL_URL', CALDAV_PRINCIPAL_URL, this.serviceId, userId);

  req = this.dav.request.propfind({
    props: [{ name: 'calendar-home-set', namespace: this.dav.ns.CALDAV }],
    depth: 0,
    mergeResponses: true,
  });

  // Get Home URL
  let CALDAV_HOME_URL;
  try {
    const {
      props: { calendarHomeSet },
    } = await xhr.send(req, CALDAV_PRINCIPAL_URL);
    CALDAV_HOME_URL = url.resolve(CALDAV_PRINCIPAL_URL, calendarHomeSet);
  } catch (e) {
    logger.error(e);
    throw new Error400('CALDAV_BAD_SETTINGS_HOME_URL');
  }

  logger.info(`CalDAV : Home URL found: ${CALDAV_HOME_URL}`);
  await this.gladys.variable.setValue('CALDAV_HOME_URL', CALDAV_HOME_URL, this.serviceId, userId);
}
@description Start configuration depending on host.
@param {object} userId - Gladys user to connect.
@returns {Promise} Resolving with client connected.
@example
config(user.id)