fix(installer): retain browsers installed via Playwrigth CLI (#5904)

Browser registry is responsible for 3 things:
1. Remove downloaded browsers if there are no packages that refer to them
2. Install default browsers needed for the current package
3. Install browsers on-demand when used through Playwright CLI

Currently, registry relies on a single "download" field in `browsers.json`
to carry both (1) and (2). However, browsers in (3) are marked as
`download: false` so that they aren't installed automatically in (2), so
auto-remove procedure in (1) removes them on subsequent installation.

One possible approach to fix this would be modifying package's `browsers.json` to
change `download: false` to `true` when browsers are installed with
Playwright CLI. This approach was explored here:
bc04a51800

We decided against this since we have a history of issues related to
package modifications after NPM installation. This breaks all
sorts of yarn/npm caching mechanisms.

Instead, this patch is a two-step refactor:
- remove the "download" field in `browsers.json`. Now, all registries
(including old ones from previously-released versions) will retain any
browsers that are mentioned in the `browsers.json`.
- add a new flag "installByDefault", that is **only used** for default
installation.

With this change, the registry tasks are done like this:
- (1) auto-removal: if browser has a back reference, it is retained,
otherwise it is removed from registry
- (2) default installation: use only `installByDefault` to carry default installations
- (3) CLI installation: simply installs browsers. Since we retain
everythings that's referenced in (1), browsers aren't removed.

Fixes #5902

browsers.json

@@ -4,17 +4,17 @@
     {
       "name": "chromium",
       "revision": "857950",
-      "download": true
+      "installByDefault": true
     },
     {
       "name": "firefox",
       "revision": "1238",
-      "download": true
+      "installByDefault": true
     },
     {
       "name": "webkit",
       "revision": "1446",
-      "download": true,
+      "installByDefault": true,
       "revisionOverrides": {
         "mac10.14": "1443"
       }
@@ -22,7 +22,7 @@
     {
       "name": "ffmpeg",
       "revision": "1005",
-      "download": true
+      "installByDefault": true
     }
   ]
 }

packages/build_package.js

@@ -163,7 +163,7 @@ if (!args.some(arg => arg === '--no-cleanup')) {
   // 5. Generate browsers.json
   const browsersJSON = require(path.join(ROOT_PATH, 'browsers.json'));
   for (const browser of browsersJSON.browsers)
-    browser.download = package.browsers.includes(browser.name);
+    browser.installByDefault = package.browsers.includes(browser.name);
   await writeToPackage('browsers.json', JSON.stringify(browsersJSON, null, 2));
 
   // 6. Bake commit SHA into the package

src/install/installer.ts

@@ -31,7 +31,7 @@ const fsWriteFileAsync = util.promisify(fs.writeFile.bind(fs));
 
 const PACKAGE_PATH = path.join(__dirname, '..', '..');
 
-export async function installBrowsersWithProgressBar(browserNames: BrowserName[] = allBrowserNames) {
+export async function installBrowsersWithProgressBar(browserNames: BrowserName[] = Registry.currentPackageRegistry().installByDefault()) {
   // PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD should have a value of 0 or 1
   if (getAsBooleanFromENV('PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD')) {
     browserFetcher.logPolitely('Skipping browsers download because `PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD` env variable is set');
@@ -74,7 +74,7 @@ async function validateCache(linksDir: string, browserNames: BrowserName[]) {
       linkTarget = (await fsReadFileAsync(linkPath)).toString();
       const linkRegistry = new Registry(linkTarget);
       for (const browserName of allBrowserNames) {
-        if (!linkRegistry.shouldDownload(browserName))
+        if (!linkRegistry.shouldRetain(browserName))
           continue;
         const usedBrowserPath = linkRegistry.browserDirectory(browserName);
         const browserRevision = linkRegistry.revision(browserName);
@@ -105,10 +105,8 @@ async function validateCache(linksDir: string, browserNames: BrowserName[]) {
   }
 
   // 3. Install missing browsers for this package.
-  const myRegistry = new Registry(PACKAGE_PATH);
+  const myRegistry = Registry.currentPackageRegistry();
   for (const browserName of browserNames) {
-    if (!myRegistry.shouldDownload(browserName))
-      continue;
     await browserFetcher.downloadBrowserWithProgressBar(myRegistry, browserName).catch(e => {
       throw new Error(`Failed to download ${browserName}, caused by\n${e.stack}`);
     });

src/utils/registry.ts

@@ -26,11 +26,13 @@ import { assert, getFromENV } from './utils';
 export type BrowserName = 'chromium'|'webkit'|'firefox'|'ffmpeg';
 export const allBrowserNames: BrowserName[] = ['chromium', 'webkit', 'firefox', 'ffmpeg'];
 
+const PACKAGE_PATH = path.join(__dirname, '..', '..');
+
 type BrowserPlatform = 'win32'|'win64'|'mac10.13'|'mac10.14'|'mac10.15'|'mac11'|'mac11-arm64'|'ubuntu18.04'|'ubuntu20.04';
 type BrowserDescriptor = {
   name: BrowserName,
   revision: string,
-  download: boolean,
+  installByDefault: boolean,
   browserDirectory: string,
 };
 
@@ -199,9 +201,17 @@ export function isBrowserDirectory(browserDirectory: string): boolean {
   return false;
 }
 
+let currentPackageRegistry: Registry | undefined = undefined;
+
 export class Registry {
   private _descriptors: BrowserDescriptor[];
 
+  static currentPackageRegistry() {
+    if (!currentPackageRegistry)
+      currentPackageRegistry = new Registry(PACKAGE_PATH);
+    return currentPackageRegistry;
+  }
+
   constructor(packagePath: string) {
     const browsersJSON = JSON.parse(fs.readFileSync(path.join(packagePath, 'browsers.json'), 'utf8'));
     this._descriptors = browsersJSON['browsers'].map((obj: any) => {
@@ -212,7 +222,7 @@ export class Registry {
       return {
         name,
         revision,
-        download: obj.download,
+        installByDefault: !!obj.installByDefault,
         browserDirectory,
       };
     });
@@ -283,10 +293,17 @@ export class Registry {
     return util.format(urlTemplate, downloadHost, browser.revision);
   }
 
-  shouldDownload(browserName: BrowserName): boolean {
+  shouldRetain(browserName: BrowserName): boolean {
-    // Older versions do not have "download" field. We assume they need all browsers
+    // We retain browsers if they are found in the descriptor.
-    // from the list. So we want to skip all browsers that are explicitly marked as "download: false".
+    // Note, however, that there are older versions out in the wild that rely on
+    // the "download" field in the browser descriptor and use its value
+    // to retain and download browsers.
+    // As of v1.10, we decided to abandon "download" field.
     const browser = this._descriptors.find(browser => browser.name === browserName);
-    return !!browser && browser.download !== false;
+    return !!browser;
+  }
+
+  installByDefault(): BrowserName[] {
+    return this._descriptors.filter(browser => browser.installByDefault).map(browser => browser.name);
   }
 }