feat(retry-plugin): allow fallback function to receive failed URL (#3133)

Co-authored-by: Zack Jackson <[email protected]>
Co-authored-by: Karina <[email protected]>

Author: 3 people

.changeset/orange-goats-hope.md

@@ -0,0 +1,5 @@
+---
+'@module-federation/retry-plugin': minor
+---
+
+Allow fallback function to receive the failed URL in order to build the fallback URL.

apps/website-new/docs/en/plugin/plugins/retry-plugin.mdx

@@ -96,7 +96,9 @@ type FetchWithRetryOptions = {
   options?: RequestInit;
   retryTimes?: number;
   retryDelay?: number;
-  fallback?: (() => string) | ((url: string | URL | globalThis.Request) => string);
+  fallback?:
+    | (() => string)
+    | ((url: string | URL | globalThis.Request) => string);
 }
 
 type ScriptWithRetryOptions = {

packages/retry-plugin/__tests__/retry.spec.ts

@@ -118,6 +118,24 @@ describe('fetchWithRetry', () => {
     expect(fetch).toHaveBeenLastCalledWith('https://fallback.com', {});
   });
 
+  it('should build fallback URL from remote after retries fail', async () => {
+    mockErrorFetch();
+    const retryTimes = 3;
+    const responsePromise = fetchWithRetry({
+      url: 'https://example.com',
+      retryTimes,
+      retryDelay: 0,
+      fallback: (url) => `${url}/fallback`,
+    });
+    vi.advanceTimersByTime(2000 * retryTimes);
+
+    await expect(responsePromise).rejects.toThrow(
+      'The request failed three times and has now been abandoned',
+    );
+    expect(fetch).toHaveBeenCalledTimes(5); //first fetch + retryTimes fetch
+    expect(fetch).toHaveBeenLastCalledWith('https://example.com/fallback', {});
+  });
+
   it('should handle JSON parse error', async () => {
     const mockFetch = vi.fn().mockResolvedValueOnce({
       ok: true,