[feat] adapter module

documentation/docs/80-adapter-api.md

@@ -23,15 +23,17 @@ export default function (options) {
 
 The types for `Adapter` and its parameters are available in [types/config.d.ts](https://github.com/sveltejs/kit/blob/master/packages/kit/types/config.d.ts).
 
-Within the `adapt` method, there are a number of things that an adapter should do:
-
-- Clear out the build directory
-- Output code that:
-  - Calls `init`
-  - Converts from the platform's request to a [SvelteKit request](#hooks-handle), calls `render`, and converts from a [SvelteKit response](#hooks-handle) to the platform's
-  - Globally shims `fetch` to work on the target platform. SvelteKit provides a `@sveltejs/kit/install-fetch` helper for platforms that can use `node-fetch`
+Within the `adapt` method, an adapter should:
+
+- Clear out the build directory before anything else
+- Import `{ appResolver }` from `@sveltejs/kit/adapter`
+- Pass in `appResolver()` to esbuild plugins for build options
+- Import `app` from `@sveltejs/kit/app`
+- Call `app.init()` as early as possible
+- Convert from the platform's request to a [SvelteKit request](#hooks-handle), call `app.render()`, and convert from a [SvelteKit response](#hooks-handle) to the platform's
+- Globally shim `fetch` to work on the target platform. SvelteKit provides a `@sveltejs/kit/install-fetch` helper for platforms that can use `node-fetch`
 - Bundle the output to avoid needing to install dependencies on the target platform, if desired
-- Call `utils.prerender`
+- Prerender static pages by calling `utils.prerender()`
 - Put the user's static files and the generated JS/CSS in the correct location for the target platform
 
 If possible, we recommend putting the adapter output under the `build/` directory with any intermediate output placed under `'.svelte-kit/' + adapterName`.

packages/adapter-cloudflare-workers/files/entry.js

@@ -1,6 +1,5 @@
-// TODO hardcoding the relative location makes this brittle
-import { init, render } from '../output/server/app.js';
 import { getAssetFromKV, NotFoundError } from '@cloudflare/kv-asset-handler';
+import { init, render } from '@sveltejs/kit/app';
 
 init();
 

packages/adapter-cloudflare-workers/index.js

@@ -1,9 +1,11 @@
-import fs from 'fs';
 import { execSync } from 'child_process';
-import esbuild from 'esbuild';
-import toml from '@iarna/toml';
+import fs from 'fs';
 import { fileURLToPath } from 'url';
 
+import toml from '@iarna/toml';
+import { appResolver } from '@sveltejs/kit/adapter';
+import esbuild from 'esbuild';
+
 /**
  * @typedef {import('esbuild').BuildOptions} BuildOptions
  */
@@ -40,7 +42,8 @@ export default function (options) {
 				outfile: `${entrypoint}/index.js`,
 				bundle: true,
 				target: 'es2020',
-				platform: 'browser'
+				platform: 'browser',
+				plugins: [appResolver()]
 			};
 
 			const build_options =

packages/adapter-netlify/files/entry.js

@@ -1,5 +1,4 @@
-// TODO hardcoding the relative location makes this brittle
-import { init, render } from '../output/server/app.js';
+import { init, render } from '@sveltejs/kit/app';
 
 init();
 

packages/adapter-netlify/index.js

@@ -1,8 +1,10 @@
-import { appendFileSync, existsSync, readFileSync, writeFileSync } from 'fs';
+import fs from 'fs';
 import { join, resolve } from 'path';
 import { fileURLToPath } from 'url';
-import esbuild from 'esbuild';
+
 import toml from '@iarna/toml';
+import { appResolver } from '@sveltejs/kit/adapter';
+import esbuild from 'esbuild';
 
 /**
  * @typedef {import('esbuild').BuildOptions} BuildOptions
@@ -34,6 +36,7 @@ export default function (options) {
 				outfile: '.netlify/functions-internal/__render.js',
 				bundle: true,
 				inject: [join(files, 'shims.js')],
+				plugins: [appResolver()],
 				platform: 'node'
 			};
 
@@ -42,7 +45,7 @@ export default function (options) {
 
 			await esbuild.build(build_options);
 
-			writeFileSync(join('.netlify', 'package.json'), JSON.stringify({ type: 'commonjs' }));
+			fs.writeFileSync(join('.netlify', 'package.json'), JSON.stringify({ type: 'commonjs' }));
 
 			utils.log.minor('Prerendering static pages...');
 			await utils.prerender({
@@ -57,20 +60,20 @@ export default function (options) {
 
 			const redirectPath = join(publish, '_redirects');
 			utils.copy('_redirects', redirectPath);
-			appendFileSync(redirectPath, '\n\n/* /.netlify/functions/__render 200');
+			fs.appendFileSync(redirectPath, '\n\n/* /.netlify/functions/__render 200');
 		}
 	};
 }
 /**
  * @param {import('@sveltejs/kit').AdapterUtils} utils
  **/
 function get_publish_directory(utils) {
-	if (existsSync('netlify.toml')) {
+	if (fs.existsSync('netlify.toml')) {
 		/** @type {{ build?: { publish?: string }} & toml.JsonMap } */
 		let netlify_config;
 
 		try {
-			netlify_config = toml.parse(readFileSync('netlify.toml', 'utf-8'));
+			netlify_config = toml.parse(fs.readFileSync('netlify.toml', 'utf-8'));
 		} catch (err) {
 			err.message = `Error parsing netlify.toml: ${err.message}`;
 			throw err;

packages/adapter-node/index.js

@@ -1,17 +1,12 @@
-import esbuild from 'esbuild';
-import {
-	createReadStream,
-	createWriteStream,
-	existsSync,
-	readFileSync,
-	statSync,
-	writeFileSync
-} from 'fs';
+import fs from 'fs';
 import { join } from 'path';
 import { pipeline } from 'stream';
-import glob from 'tiny-glob';
 import { fileURLToPath } from 'url';
 import { promisify } from 'util';
+
+import { appResolver } from '@sveltejs/kit/adapter';
+import esbuild from 'esbuild';
+import glob from 'tiny-glob';
 import zlib from 'zlib';
 
 const pipe = promisify(pipeline);
@@ -46,8 +41,8 @@ export default function ({
 			utils.log.minor('Building SvelteKit middleware');
 			const files = fileURLToPath(new URL('./files', import.meta.url));
 			utils.copy(files, '.svelte-kit/node');
-			writeFileSync(
-				'.svelte-kit/node/env.js',
+			fs.writeFileSync(
+				'.svelte-kit/node/env.js', // types pointed in src/env.d.ts
 				`export const path = process.env[${JSON.stringify(
 					path_env
 				)}] || false;\nexport const host = process.env[${JSON.stringify(
@@ -58,20 +53,26 @@ export default function ({
 			);
 
 			/** @type {BuildOptions} */
-			const defaultOptions = {
+			const default_options = {
 				entryPoints: ['.svelte-kit/node/middlewares.js'],
 				outfile: join(out, 'middlewares.js'),
 				bundle: true,
-				external: Object.keys(JSON.parse(readFileSync('package.json', 'utf8')).dependencies || {}),
+				external: Object.keys(
+					JSON.parse(fs.readFileSync('package.json', 'utf8')).dependencies || {}
+				),
 				format: 'esm',
 				platform: 'node',
 				target: 'node12',
 				inject: [join(files, 'shims.js')],
+				plugins: [appResolver()],
 				define: {
 					APP_DIR: `"/${config.kit.appDir}/"`
 				}
 			};
-			const build_options = esbuild_config ? await esbuild_config(defaultOptions) : defaultOptions;
+
+			const build_options = esbuild_config
+				? await esbuild_config(default_options)
+				: default_options;
 			await esbuild.build(build_options);
 
 			utils.log.minor('Building SvelteKit reference server');
@@ -95,6 +96,7 @@ export default function ({
 					}
 				]
 			};
+
 			const build_options_ref_server = esbuild_config
 				? await esbuild_config(default_options_ref_server)
 				: default_options_ref_server;
@@ -104,7 +106,7 @@ export default function ({
 			await utils.prerender({
 				dest: `${out}/prerendered`
 			});
-			if (precompress && existsSync(`${out}/prerendered`)) {
+			if (precompress && fs.existsSync(`${out}/prerendered`)) {
 				utils.log.minor('Compressing prerendered pages');
 				await compress(`${out}/prerendered`);
 			}
@@ -139,13 +141,13 @@ async function compress_file(file, format = 'gz') {
 					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.constants.BROTLI_PARAM_SIZE_HINT]: fs.statSync(file).size
 					}
 			  })
 			: zlib.createGzip({ level: zlib.constants.Z_BEST_COMPRESSION });
 
-	const source = createReadStream(file);
-	const destination = createWriteStream(`${file}.${format}`);
+	const source = fs.createReadStream(file);
+	const destination = fs.createWriteStream(`${file}.${format}`);
 
 	await pipe(source, compress, destination);
 }

packages/adapter-node/rollup.config.js

@@ -21,7 +21,12 @@ export default [
 			sourcemap: true
 		},
 		plugins: [nodeResolve(), commonjs(), json()],
-		external: ['./middlewares.js', './env.js', ...require('module').builtinModules]
+		external: [
+			'@sveltejs/kit/app',
+			'./middlewares.js',
+			'./env.js',
+			...require('module').builtinModules
+		]
 	},
 	{
 		input: 'src/shims.js',

packages/adapter-node/src/env.d.ts

@@ -0,0 +1,3 @@
+export const host: string;
+export const path: string;
+export const port: number;

packages/adapter-node/src/index.js

@@ -1,4 +1,3 @@
-// @ts-ignore
 import { path, host, port } from './env.js';
 import { assetsMiddleware, kitMiddleware, prerenderedMiddleware } from './middlewares.js';
 import compression from 'compression';

packages/adapter-node/src/kit-middleware.js

@@ -1,10 +1,9 @@
 import { getRawBody } from '@sveltejs/kit/node';
 
 /**
+ * @param {import('@sveltejs/kit').App} app
  * @return {import('polka').Middleware}
  */
-// TODO: type render function from @sveltejs/kit/adapter
-// @ts-ignore
 export function create_kit_middleware({ render }) {
 	return async (req, res) => {
 		const parsed = new URL(req.url || '', 'http://localhost');
@@ -20,7 +19,8 @@ export function create_kit_middleware({ render }) {
 
 		const rendered = await render({
 			method: req.method,
-			headers: req.headers, // TODO: what about repeated headers, i.e. string[]
+			// @ts-expect-error - TODO: what about repeated headers, i.e. string[]
+			headers: req.headers,
 			path: parsed.pathname,
 			query: parsed.searchParams,
 			rawBody: body

packages/adapter-node/src/middlewares.js

@@ -1,16 +1,12 @@
-// TODO hardcoding the relative location makes this brittle
-// Also, we need most of the logic in another file for testing because
-// ../output/server/app.js doesn't exist when we run the tests
-// @ts-ignore
-import { init, render } from '../output/server/app.js';
-import { create_kit_middleware } from './kit-middleware.js';
-
 import fs from 'fs';
 import { dirname, join } from 'path';
-import sirv from 'sirv';
 import { fileURLToPath } from 'url';
 
-// App is a dynamic file built from the application layer.
+import app from '@sveltejs/kit/app';
+import sirv from 'sirv';
+import { create_kit_middleware } from './kit-middleware.js';
+
+app.init();
 
 const __dirname = dirname(fileURLToPath(import.meta.url));
 /** @type {import('polka').Middleware} */
@@ -42,7 +38,4 @@ export const assetsMiddleware = fs.existsSync(paths.assets)
 	  })
 	: noop_handler;
 
-export const kitMiddleware = (function () {
-	init();
-	return create_kit_middleware({ render });
-})();
+export const kitMiddleware = create_kit_middleware(app);

packages/adapter-vercel/files/entry.js

@@ -1,8 +1,6 @@
+import { init, render } from '@sveltejs/kit/app';
 import { getRawBody } from '@sveltejs/kit/node';
 
-// TODO hardcoding the relative location makes this brittle
-import { init, render } from '../output/server/app.js';
-
 init();
 
 export default async (req, res) => {

packages/adapter-vercel/index.js

@@ -1,6 +1,8 @@
 import { writeFileSync } from 'fs';
 import { join } from 'path';
 import { fileURLToPath } from 'url';
+
+import { appResolver } from '@sveltejs/kit/adapter';
 import esbuild from 'esbuild';
 
 /**
@@ -37,6 +39,7 @@ export default function (options) {
 				outfile: join(dirs.lambda, 'index.js'),
 				bundle: true,
 				inject: [join(files, 'shims.js')],
+				plugins: [appResolver()],
 				platform: 'node'
 			};
 

packages/kit/package.json

@@ -21,6 +21,7 @@
 		"amphtml-validator": "^1.0.34",
 		"cookie": "^0.4.1",
 		"devalue": "^2.0.1",
+		"esbuild": "^0.12.5",
 		"eslint": "^7.25.0",
 		"kleur": "^4.1.4",
 		"locate-character": "^2.0.5",
@@ -66,6 +67,9 @@
 	},
 	"exports": {
 		"./package.json": "./package.json",
+		"./adapter": {
+			"import": "./dist/adapter.js"
+		},
 		"./ssr": {
 			"import": "./dist/ssr.js"
 		},

packages/kit/rollup.config.js

@@ -46,6 +46,7 @@ export default [
 	{
 		input: {
 			cli: 'src/cli.js',
+			adapter: 'src/core/adapt/plugins.js',
 			ssr: 'src/runtime/server/index.js',
 			node: 'src/core/node/index.js',
 			hooks: 'src/runtime/hooks.js',

packages/kit/src/core/adapt/plugins.js

@@ -0,0 +1,13 @@
+import { join } from 'path';
+
+/** @type {import('@sveltejs/kit/adapter').AppResolver} */
+export function appResolver() {
+	return {
+		name: '@sveltejs/esbuild-plugin-app-resolver',
+		setup(build) {
+			build.onResolve({ filter: /@sveltejs\/kit\/app/ }, (args) => ({
+				path: join(args.resolveDir, '../output/server/app.js')
+			}));
+		}
+	};
+}

packages/kit/src/core/adapt/prerender.js

@@ -1,11 +1,13 @@
 import { readFileSync, writeFileSync } from 'fs';
 import { dirname, join, resolve as resolve_path } from 'path';
 import { pathToFileURL, resolve, URL } from 'url';
-import { mkdirp } from '../../utils/filesystem.js';
+
 import { __fetch_polyfill } from '../../install-fetch.js';
-import { SVELTE_KIT } from '../constants.js';
+import { mkdirp } from '../../utils/filesystem.js';
 import { get_single_valued_header } from '../../utils/http.js';
 
+import { SVELTE_KIT } from '../constants.js';
+
 /**
  * @typedef {import('types/config').PrerenderErrorHandler} PrerenderErrorHandler
  * @typedef {import('types/config').PrerenderOnErrorValue} OnError

packages/kit/src/core/build/index.js

@@ -90,7 +90,6 @@ export async function build(config, { cwd = process.cwd(), runtime = '@sveltejs/
  *   build_dir: string;
  *   output_dir: string;
  *   client_entry_file: string;
- *   service_worker_entry_file: string | null;
  * }} options
  */
 async function build_client({
@@ -421,6 +420,9 @@ async function build_server(
 				const host = ${config.kit.host ? s(config.kit.host) : `request.headers[${s(config.kit.hostHeader || 'host')}]`};
 				return respond({ ...request, host }, options, { prerender });
 			}
+
+			const app = { init, render };
+			export default app;
 		`
 			.replace(/^\t{3}/gm, '')
 			.trim()