elastic-apm-node/lib/apm-client/http-apm-client/central-config.js

The official Elastic APM agent for Node.js

/*
 * Copyright Elasticsearch B.V. and other contributors where applicable.
 * Licensed under the BSD 2-Clause License; you may not use this file except in
 * compliance with the BSD 2-Clause License.
 */

'use strict';

// Central config-related utilities for the APM http client.

const INTERVAL_DEFAULT_S = 300; // 5 min
const INTERVAL_MIN_S = 5;
const INTERVAL_MAX_S = 86400; // 1d

/**
 * Determine an appropriate delay until the next fetch of Central Config.
 * Default to 5 minutes, minimum 5s, max 1d.
 *
 * The maximum of 1d ensures we don't get surprised by an overflow value to
 * `setTimeout` per https://developer.mozilla.org/en-US/docs/Web/API/setTimeout#maximum_delay_value
 *
 * @param {Number|undefined} seconds - A number of seconds, typically pulled
 *    from a `Cache-Control: max-age=${seconds}` header on a previous central
 *    config request.
 * @returns {Number}
 */
function getCentralConfigIntervalS(seconds) {
  if (typeof seconds !== 'number' || isNaN(seconds) || seconds <= 0) {
    return INTERVAL_DEFAULT_S;
  }
  return Math.min(Math.max(seconds, INTERVAL_MIN_S), INTERVAL_MAX_S);
}

module.exports = {
  getCentralConfigIntervalS,

  // These are exported for testing.
  INTERVAL_DEFAULT_S,
  INTERVAL_MIN_S,
  INTERVAL_MAX_S,
};