fix: ensure axios headers are instance of AxiosHeaders via interceptor (

#515)

src/http_client.ts

@@ -4,7 +4,14 @@ import { APIFY_ENV_VARS } from '@apify/consts';
 import { Log } from '@apify/log';
 import KeepAliveAgent from 'agentkeepalive';
 import retry, { RetryFunction } from 'async-retry';
-import axios, { AxiosError, AxiosInstance, AxiosRequestConfig, InternalAxiosRequestConfig, AxiosResponse } from 'axios';
+import axios, {
+    AxiosError,
+    AxiosInstance,
+    AxiosRequestConfig,
+    InternalAxiosRequestConfig,
+    AxiosResponse,
+    AxiosHeaders,
+} from 'axios';
 
 import { ApifyApiError } from './apify_api_error';
 import {
@@ -99,7 +106,7 @@ export class HttpClient {
         });
 
         // Clean all default headers because they only make a mess and their merging is difficult to understand and buggy.
-        this.axios.defaults.headers = {} as any;
+        this.axios.defaults.headers = new AxiosHeaders() as any;
 
         // If workflow key is available, pass it as a header
         if (this.workflowKey) {

src/interceptors.ts

@@ -1,4 +1,4 @@
-import axios, { AxiosInterceptorManager, AxiosResponse, AxiosRequestTransformer } from 'axios';
+import axios, { AxiosInterceptorManager, AxiosResponse, AxiosRequestTransformer, AxiosHeaders } from 'axios';
 import contentTypeParser from 'content-type';
 import { JsonObject } from 'type-fest';
 
@@ -62,6 +62,14 @@ function serializeRequest(config: ApifyRequestConfig): ApifyRequestConfig {
     return config;
 }
 
+function ensureHeadersPrototype(config: ApifyRequestConfig): ApifyRequestConfig {
+    if (config.headers && !(config.headers instanceof AxiosHeaders)) {
+        Object.setPrototypeOf(config.headers, AxiosHeaders.prototype);
+    }
+
+    return config;
+}
+
 /**
  * JSON.stringify() that serializes functions to string instead
  * of replacing them with null or removing them.
@@ -114,5 +122,5 @@ function parseResponseData(response: ApifyResponse): ApifyResponse {
 export type RequestInterceptorFunction = Parameters<AxiosInterceptorManager<ApifyRequestConfig>['use']>[0];
 export type ResponseInterceptorFunction = Parameters<AxiosInterceptorManager<ApifyResponse>['use']>[0];
 
-export const requestInterceptors: RequestInterceptorFunction[] = [maybeGzipRequest, serializeRequest];
+export const requestInterceptors: RequestInterceptorFunction[] = [maybeGzipRequest, serializeRequest, ensureHeadersPrototype];
 export const responseInterceptors: ResponseInterceptorFunction[] = [parseResponseData];

test/http_client.test.js

@@ -27,6 +27,10 @@ describe('HttpClient', () => {
             baseUrl,
             timeoutSecs: 1,
             maxRetries: 0,
+            requestInterceptors: [(config) => {
+                config.headers = {};
+                return config;
+            }],
         });
     });
     afterEach(async () => {