feat(adapter-node): precompress (gzip & brotli) assets (#1693)

.changeset/clever-eagles-live.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-node': patch
+---
+
+precompress assets and prerendered pages (html,js,json,css,svg,xml)

packages/adapter-node/README.md

@@ -15,6 +15,7 @@ export default {
 		adapter: adapter({
 			// default options are shown
 			out: 'build'
+			precompress: false,
 		})
 	}
 };
@@ -26,6 +27,10 @@ export default {
 
 The directory to build the server to. It defaults to `build` — i.e. `node build` would start the server locally after it has been created.
 
+### precompress
+
+Enables precompressing using gzip and brotli for assets and prerendered pages. It defaults to `false`.
+
 ## Environment variables
 
 By default, the server will accept connections on `0.0.0.0` using port 3000. These can be customised with the `PORT` and `HOST` environment variables:

packages/adapter-node/index.d.ts

@@ -1,3 +1,6 @@
-declare function plugin(options?: { out?: string }): import('@sveltejs/kit').Adapter;
+declare function plugin(options?: {
+	out?: string;
+	precompress?: boolean;
+}): import('@sveltejs/kit').Adapter;
 
 export = plugin;

packages/adapter-node/index.js

@@ -1,14 +1,21 @@
-import esbuild from 'esbuild';
-import { readFileSync } from 'fs';
+import { readFileSync, statSync, createReadStream, createWriteStream } from 'fs';
 import { join } from 'path';
 import { fileURLToPath } from 'url';
+import { pipeline } from 'stream';
+import { promisify } from 'util';
+import zlib from 'zlib';
+import esbuild from 'esbuild';
+import glob from 'tiny-glob';
+
+const pipe = promisify(pipeline);
 
 /**
  * @param {{
  *   out?: string;
+ *   precompress?: boolean
  * }} options
  */
-export default function ({ out = 'build' } = {}) {
+export default function ({ out = 'build', precompress } = {}) {
 	/** @type {import('@sveltejs/kit').Adapter} */
 	const adapter = {
 		name: '@sveltejs/adapter-node',
@@ -19,6 +26,11 @@ export default function ({ out = 'build' } = {}) {
 			utils.copy_client_files(static_directory);
 			utils.copy_static_files(static_directory);
 
+			if (precompress) {
+				utils.log.minor('Compressing assets');
+				await compress(static_directory);
+			}
+
 			utils.log.minor('Building server');
 			const files = fileURLToPath(new URL('./files', import.meta.url));
 			utils.copy(files, '.svelte-kit/node');
@@ -39,8 +51,52 @@ export default function ({ out = 'build' } = {}) {
 			await utils.prerender({
 				dest: `${out}/prerendered`
 			});
+			if (precompress) {
+				utils.log.minor('Compressing prerendered pages');
+				await compress(`${out}/prerendered`);
+			}
 		}
 	};
 
 	return adapter;
 }
+
+/**
+ * @param {string} directory
+ */
+async function compress(directory) {
+	const files = await glob('**/*.{html,js,json,css,svg,xml}', {
+		cwd: directory,
+		dot: true,
+		absolute: true,
+		filesOnly: true
+	});
+
+	await Promise.all(
+		files.map((file) => Promise.all([compress_file(file, 'gz'), compress_file(file, 'br')]))
+	);
+}
+
+/**
+ * @param {string} file
+ * @param {'gz' | 'br'} format
+ */
+async function compress_file(file, format = 'gz') {
+	const compress =
+		format == 'br'
+			? zlib.createBrotliCompress({
+					params: {
+						[zlib.constants.BROTLI_PARAM_MODE]: zlib.constants.BROTLI_MODE_TEXT,
+						[zlib.constants.BROTLI_PARAM_QUALITY]: zlib.constants.BROTLI_MAX_QUALITY,
+						[zlib.constants.BROTLI_PARAM_SIZE_HINT]: statSync(file).size
+					}
+			  })
+			: zlib.createGzip({
+					level: zlib.constants.Z_BEST_COMPRESSION
+			  });
+
+	const source = createReadStream(file);
+	const destination = createWriteStream(`${file}.${format}`);
+
+	await pipe(source, compress, destination);
+}

packages/adapter-node/package.json

@@ -21,7 +21,8 @@
 		"prepublishOnly": "npm run build"
 	},
 	"dependencies": {
-		"esbuild": "^0.12.5"
+		"esbuild": "^0.12.5",
+		"tiny-glob": "^0.2.9"
 	},
 	"devDependencies": {
 		"@rollup/plugin-json": "^4.1.0",

packages/adapter-node/src/server.js

@@ -17,12 +17,6 @@ const paths = {
 };
 
 export function createServer({ render }) {
-	const mutable = (dir) =>
-		sirv(dir, {
-			etag: true,
-			maxAge: 0
-		});
-
 	const immutable_path = (pathname) => {
 		// eslint-disable-next-line no-undef
 		let app_dir = esbuild_app_dir;
@@ -43,7 +37,12 @@ export function createServer({ render }) {
 	};
 
 	const prerendered_handler = fs.existsSync(paths.prerendered)
-		? mutable(paths.prerendered)
+		? sirv(paths.prerendered, {
+				etag: true,
+				maxAge: 0,
+				gzip: true,
+				brotli: true
+		  })
 		: noop_handler;
 
 	const assets_handler = fs.existsSync(paths.assets)