fix: consider downloadHost as baseUrl (#9973)

packages/browsers/src/fetch.ts

@@ -63,6 +63,16 @@ export interface Options {
     downloadedBytes: number,
     totalBytes: number
   ) => void;
+  /**
+   * Determines the host that will be used for downloading.
+   *
+   * @defaultValue Either
+   *
+   * - https://storage.googleapis.com/chromium-browser-snapshots or
+   * - https://archive.mozilla.org/pub/firefox/nightly/latest-mozilla-central
+   *
+   */
+  baseUrl?: string;
 }
 
 export type InstalledBrowser = {
@@ -82,7 +92,8 @@ export async function fetch(options: Options): Promise<InstalledBrowser> {
   const url = getDownloadUrl(
     options.browser,
     options.platform,
-    options.buildId
+    options.buildId,
+    options.baseUrl
   );
   const fileName = url.toString().split('/').pop();
   assert(fileName, `A malformed download URL was found: ${url}.`);
@@ -131,14 +142,20 @@ export async function canFetch(options: Options): Promise<boolean> {
     );
   }
   return await headHttpRequest(
-    getDownloadUrl(options.browser, options.platform, options.buildId)
+    getDownloadUrl(
+      options.browser,
+      options.platform,
+      options.buildId,
+      options.baseUrl
+    )
   );
 }
 
 function getDownloadUrl(
   browser: Browser,
   platform: BrowserPlatform,
-  buildId: string
+  buildId: string,
+  baseUrl?: string
 ): URL {
-  return new URL(downloadUrls[browser](platform, buildId));
+  return new URL(downloadUrls[browser](platform, buildId, baseUrl));
 }

packages/puppeteer/src/node/install.ts

@@ -48,6 +48,8 @@ export async function downloadBrowser(): Promise<void> {
     return;
   }
 
+  let downloadHost = configuration.downloadHost;
+
   let platform = detectBrowserPlatform();
   if (!platform) {
     throw new Error('The current platform is not supported.');
@@ -70,6 +72,19 @@ export async function downloadBrowser(): Promise<void> {
     PUPPETEER_REVISIONS[product === 'chrome' ? 'chromium' : 'firefox'] ||
     'latest';
 
+  if (product === 'chrome' && downloadHost) {
+    // TODO: remove downloadHost in favour of baseDownloadUrl. The "host" of
+    // Firefox is already a URL and not a host. This would be a breaking change.
+    if (
+      !downloadHost.endsWith('/chromium-browser-snapshots') &&
+      !downloadHost.endsWith('/chromium-browser-snapshots/')
+    ) {
+      downloadHost += downloadHost.endsWith('/')
+        ? 'chromium-browser-snapshots'
+        : '/chromium-browser-snapshots';
+    }
+  }
+
   const buildId = await resolveBuildId(browser, platform, unresolvedBuildId);
 
   try {
@@ -79,6 +94,7 @@ export async function downloadBrowser(): Promise<void> {
       platform,
       buildId,
       downloadProgressCallback: makeProgressCallback(browser, buildId),
+      baseUrl: downloadHost,
     });
 
     logPolitely(