requestCorrelator.ts

/*!
 * Copyright (c) 2020 Ville de Montreal. All rights reserved.
 * Licensed under the MIT license.
 * See LICENSE file in the project root for full license information.
 */
import { AxiosRequestConfig } from 'axios';
import { IHttpRequestCorrelator } from '@villedemontreal/auth-core';
import { IAxiosPlugin } from './IAxiosPlugin';
import { makeAxiosPlugin } from './makeAxiosPlugin';
import { getHeader } from './requestUtils';

/**
 * plugin that will automatically inject a correlation ID generated by the
 * submitted provider into the standard "x-correlation-id" header.
 * Note that your correlation ID provider should rely on CLS (Continuation Local Storage)
 * to make the current correlation ID available to any async hooks created from
 * the incoming HTTP request.
 * @param correlator the correlator used to tag outgoing requests with a Correlation-ID header.
 * @example
 * const correlator =  new HttpRequestCorrelator();
 * const config: AxiosRequestConfig = {
 *   url: 'http://localhost:4004/secured/profile'
 * };
 * requestCorrelator(correlator).bind(config);
 * requestLogger(new ConsoleLogger(() => correlator.getId())).bind(config);
 * const response = await axios.request(config);
 */
export function requestCorrelator(
  correlator: IHttpRequestCorrelator,
): IAxiosPlugin {
  return makeAxiosPlugin({
    //--------------------------------------------------------------------
    onStart(config: AxiosRequestConfig): Promise<void> {
      if (!getHeader(config, 'x-correlation-id')) {
        const value = correlator.getId();
        if (value) {
          config.headers = {
            ...config.headers,
            ['x-correlation-id']: value,
          };
        }
      }
      return Promise.resolve();
    },
  });
}