dd-trace/packages/dd-trace/src/openfeature/flagging_provider.js

Datadog APM tracing client for JavaScript

'use strict'

const { channel } = require('dc-polyfill')
const log = require('../log')
const configurationSource = require('./configuration_source')
const { EXPOSURE_CHANNEL } = require('./constants/constants')
const EvalMetricsHook = require('./eval-metrics-hook')
const SpanEnrichmentHook = require('./span-enrichment-hook')

const { DatadogNodeServerProvider } = require('./require-provider')

/**
 * OpenFeature provider that integrates with Datadog's feature flagging system.
 * Extends DatadogNodeServerProvider to add tracer integration and configuration management.
 */
class FlaggingProvider extends DatadogNodeServerProvider {
  /** @type {SpanEnrichmentHook | undefined} */
  #spanEnrichmentHook

  /** @type {{ start: Function, stop: Function } | undefined} */
  #configurationSource

  /**
   * @param {import('../tracer')} tracer - Datadog tracer instance
   * @param {import('../config/config-base')} config - Tracer configuration object
   */
  constructor (tracer, config) {
    super({
      exposureChannel: channel(EXPOSURE_CHANNEL),
      initializationTimeoutMs: config.experimental.flaggingProvider.initializationTimeoutMs,
    })

    this.hooks.push(new EvalMetricsHook(config))

    if (config.experimental.flaggingProvider.spanEnrichment?.enabled) {
      this.#spanEnrichmentHook = new SpanEnrichmentHook(tracer)
      // @ts-expect-error The upstream constructor always initializes its optional hooks property.
      this.hooks.push(this.#spanEnrichmentHook)
      log.info('%s span enrichment enabled', this.constructor.name)
    } else {
      log.info('%s span enrichment disabled', this.constructor.name)
    }

    log.debug('%s created with timeout: %dms', this.constructor.name,
      config.experimental.flaggingProvider.initializationTimeoutMs)

    this.#configurationSource = configurationSource.create(config, this.setConfiguration.bind(this))
    this.#configurationSource?.start()
  }

  /**
   * Called when the provider is shut down.
   * Cleans up resources including channel subscriptions.
   */
  onClose () {
    this.#configurationSource?.stop()
    this.#configurationSource = undefined
    this.#spanEnrichmentHook?.destroy()
    this.#spanEnrichmentHook = undefined
  }
}

module.exports = FlaggingProvider