[Feature] Dry run mode for install-deps

[jawnsy]

When running Playwright tests in a containerized environment, it is helpful to build a custom image with native dependencies preinstalled. It is possible to do this by manually examining the list of dependencies in the nativeDeps.ts file:

playwright/packages/playwright-core/src/utils/nativeDeps.ts

Lines 228 to 242 in d34f997

	'ubuntu20.04': {
	tools: [
	'xvfb',
	'fonts-noto-color-emoji',
	'ttf-unifont',
	'libfontconfig',
	'libfreetype6',
	'xfonts-cyrillic',
	'xfonts-scalable',
	'fonts-liberation',
	'fonts-ipafont-gothic',
	'fonts-wqy-zenhei',
	'fonts-tlwg-loma-otf',
	'ttf-ubuntu-font-family',
	],

However, it would be convenient if there were a way to list all the dependencies that playwright would install, without actually running the install command. It looks like we can do this by separating the dependency list generation and installation commands, for example, create a function that returns uniqueLibraries and a separate function that accepts that as input, then spawns apt-get:

playwright/packages/playwright-core/src/utils/dependencies.ts

Lines 49 to 72 in d34f997

	export async function installDependenciesLinux(targets: Set<DependencyGroup>) {
	const libraries: string[] = [];
	for (const target of targets) {
	const info = deps[utils.hostPlatform];
	if (!info) {
	console.warn('Cannot install dependencies for this linux distribution!'); // eslint-disable-line no-console
	return;
	}
	libraries.push(...info[target]);
	}
	const uniqueLibraries = Array.from(new Set(libraries));
	console.log('Installing Ubuntu dependencies...'); // eslint-disable-line no-console
	const commands: string[] = [];
	commands.push('apt-get update');
	commands.push(['apt-get', 'install', '-y', '--no-install-recommends',
	...uniqueLibraries,
	].join(' '));
	const [command, args] = await buildAptProcessArgs(commands);
	const child = childProcess.spawn(command, args, { stdio: 'inherit' });
	await new Promise((resolve, reject) => {
	child.on('exit', resolve);
	child.on('error', reject);
	});
	}

I'd be happy to create a pull request if this is a feature you'd consider! I'd propose something like npx playwright install-deps --dry-run to return the package list for the current system

[aslushnikov]

Jonathan Yu (@jawnsy) so what is the usecase, once again? Why don't you just run npx playwright install-deps as a step during container build?

[jawnsy]

We pin the playwright version in our packages.json, and our container build doesn't have our source code.

I suppose that we could use npx playwright install-deps to install all the deps for the latest version, but we didn't want to rely on Playwright's dependencies being backward-compatible (that is, installing playwright deps for 1.16.3 might not be the right deps for 1.15.2)

I suppose that we could mount the packages.json and use npx as an alternative

[JoelEinbinder]

While you generally you should run npx playwright install-deps from the package.json folder, if you dont have it and know the playwright version you can do:

npx --package=playwright-core@1.16.3 playwright install-deps

Which will install the deps for that specific version. Seems like a better solution for you than manually copying the list of dependencies as they update.