Allow custom fetch function to be provided

.generator/src/generator/templates/configuration.j2

@@ -106,6 +106,10 @@ export interface ConfigurationParameters {
    * Default index of a server to use for an operation from the predefined server operation map
    */
   operationServerIndices?: { [ name: string ]: number };
+  /**
+   * Custom `fetch` function
+   */
+  fetch?: any;
   /**
    * HTTP library to use e.g. IsomorphicFetch
    */
@@ -180,7 +184,7 @@ export function createConfiguration(conf: ConfigurationParameters = {}): Configu
     conf.baseServer,
     conf.serverIndex || 0,
     conf.operationServerIndices || {},
-    conf.httpApi || new DefaultHttpLibrary(),
+    conf.httpApi || new DefaultHttpLibrary({ fetch: conf.fetch }),
     configureAuthMethods(authMethods),
     conf.httpConfig || {},
     conf.debug,

.generator/src/generator/templates/http/isomorphic-fetch.j2

@@ -12,6 +12,17 @@ export class IsomorphicFetchHttpLibrary implements HttpLibrary {
   public maxRetries!: number ;
   public backoffBase!: number ;
   public backoffMultiplier!: number;
+  #fetch: any;
+
+  constructor({ fetch: customFetch }: { fetch?: any }) {
+    this.#fetch =
+      customFetch ||
+      // On non-node environments, use native fetch if available.
+      // `cross-fetch` incorrectly assumes all browsers have XHR available.
+      // See https://github.com/lquixada/cross-fetch/issues/78
+      // TODO: Remove once once above issue is resolved.
+      (!isNode && typeof fetch === "function" ? fetch : crossFetch);
+  }
 
   public send(request: RequestContext): Promise<ResponseContext> {
     if (this.debug) {
@@ -61,19 +72,14 @@ export class IsomorphicFetchHttpLibrary implements HttpLibrary {
     currentAttempt: number,
     headers: {[key: string]: string}
   ): Promise<ResponseContext> {
-    // On non-node environments, use native fetch if available.
-    // `cross-fetch` incorrectly assumes all browsers have XHR available.
-    // See https://github.com/lquixada/cross-fetch/issues/78
-    // TODO: Remove once once above issue is resolved.
-    const fetchFunction =!isNode && typeof fetch === "function" ? fetch : crossFetch;
     const fetchOptions = {
       method: request.getHttpMethod().toString(),
       body: body,
       headers: headers,
       signal: request.getHttpConfig().signal,
     }
     try {
-      const resp  = await fetchFunction(request.getUrl(),fetchOptions);
+      const resp  = await this.#fetch(request.getUrl(),fetchOptions);
       const responseHeaders: { [name: string]: string } = {};
         resp.headers.forEach((value: string, name: string) => {
           responseHeaders[name] = value;

packages/datadog-api-client-common/configuration.ts

@@ -120,6 +120,10 @@ export interface ConfigurationParameters {
    * Default index of a server to use for an operation from the predefined server operation map
    */
   operationServerIndices?: { [name: string]: number };
+  /**
+   * Custom `fetch` function
+   */
+  fetch?: any;
   /**
    * HTTP library to use e.g. IsomorphicFetch
    */
@@ -205,7 +209,7 @@ export function createConfiguration(
     conf.baseServer,
     conf.serverIndex || 0,
     conf.operationServerIndices || {},
-    conf.httpApi || new DefaultHttpLibrary(),
+    conf.httpApi || new DefaultHttpLibrary({ fetch: conf.fetch }),
     configureAuthMethods(authMethods),
     conf.httpConfig || {},
     conf.debug,

packages/datadog-api-client-common/http/isomorphic-fetch.ts

@@ -17,6 +17,17 @@ export class IsomorphicFetchHttpLibrary implements HttpLibrary {
   public maxRetries!: number;
   public backoffBase!: number;
   public backoffMultiplier!: number;
+  #fetch: any;
+
+  constructor({ fetch: customFetch }: { fetch?: any }) {
+    this.#fetch =
+      customFetch ||
+      // On non-node environments, use native fetch if available.
+      // `cross-fetch` incorrectly assumes all browsers have XHR available.
+      // See https://github.com/lquixada/cross-fetch/issues/78
+      // TODO: Remove once once above issue is resolved.
+      (!isNode && typeof fetch === "function" ? fetch : crossFetch);
+  }
 
   public send(request: RequestContext): Promise<ResponseContext> {
     if (this.debug) {
@@ -66,20 +77,14 @@ export class IsomorphicFetchHttpLibrary implements HttpLibrary {
     currentAttempt: number,
     headers: { [key: string]: string }
   ): Promise<ResponseContext> {
-    // On non-node environments, use native fetch if available.
-    // `cross-fetch` incorrectly assumes all browsers have XHR available.
-    // See https://github.com/lquixada/cross-fetch/issues/78
-    // TODO: Remove once once above issue is resolved.
-    const fetchFunction =
-      !isNode && typeof fetch === "function" ? fetch : crossFetch;
     const fetchOptions = {
       method: request.getHttpMethod().toString(),
       body: body,
       headers: headers,
       signal: request.getHttpConfig().signal,
     };
     try {
-      const resp = await fetchFunction(request.getUrl(), fetchOptions);
+      const resp = await this.#fetch(request.getUrl(), fetchOptions);
       const responseHeaders: { [name: string]: string } = {};
       resp.headers.forEach((value: string, name: string) => {
         responseHeaders[name] = value;

tests/api/retry.test.ts

@@ -9,7 +9,7 @@ import {
 describe("IsomorphicFetchHttpLibrary Retry Test", () => {
 
     const fakeRequestContext = new RequestContext("https://retry.test.com",HttpMethod.GET);
-    const httpLibrary = new IsomorphicFetchHttpLibrary();
+    const httpLibrary = new IsomorphicFetchHttpLibrary({fetch: null});
     httpLibrary['sleep'] = jest.fn(() => Promise.resolve());
     httpLibrary.enableRetry = true;
     httpLibrary.maxRetries = 3;