index.js

import { readFileSync, writeFileSync } from 'node:fs';
import { fileURLToPath } from 'node:url';
import { rollup } from 'rollup';
import { nodeResolve } from '@rollup/plugin-node-resolve';
import commonjs from '@rollup/plugin-commonjs';
import json from '@rollup/plugin-json';

const files = fileURLToPath(new URL('./files', import.meta.url).href);

/** @type {import('.').default} */
export default function (opts = {}) {
	const { out = 'build', precompress, envPrefix = '', polyfill = true } = opts;

	return {
		name: '@sveltejs/adapter-node',

		async adapt(builder) {
			const tmp = builder.getBuildDirectory('adapter-node');

			builder.rimraf(out);
			builder.rimraf(tmp);
			builder.mkdirp(tmp);

			builder.log.minor('Copying assets');
			builder.writeClient(`${out}/client${builder.config.kit.paths.base}`);
			builder.writePrerendered(`${out}/prerendered${builder.config.kit.paths.base}`);

			if (precompress) {
				builder.log.minor('Compressing assets');
				await Promise.all([
					builder.compress(`${out}/client`),
					builder.compress(`${out}/prerendered`)
				]);
			}

			builder.log.minor('Building server');

			builder.writeServer(tmp);

			writeFileSync(
				`${tmp}/manifest.js`,
				`export const manifest = ${builder.generateManifest({ relativePath: './' })};\n\n` +
					`export const prerendered = new Set(${JSON.stringify(builder.prerendered.paths)});\n`
			);

			const pkg = JSON.parse(readFileSync('package.json', 'utf8'));

			// we bundle the Vite output so that deployments only need
			// their production dependencies. Anything in devDependencies
			// will get included in the bundled code
			const bundle = await rollup({
				input: {
					index: `${tmp}/index.js`,
					manifest: `${tmp}/manifest.js`
				},
				external: [
					// dependencies could have deep exports, so we need a regex
					...Object.keys(pkg.dependencies || {}).map((d) => new RegExp(`^${d}(\\/.*)?$`))
				],
				plugins: [
					nodeResolve({
						preferBuiltins: true,
						exportConditions: ['node']
					}),
					commonjs({ strictRequires: true }),
					json()
				]
			});

			await bundle.write({
				dir: `${out}/server`,
				format: 'esm',
				sourcemap: true,
				chunkFileNames: `chunks/[name]-[hash].js`
			});

			builder.copy(files, out, {
				replace: {
					ENV: './env.js',
					HANDLER: './handler.js',
					MANIFEST: './server/manifest.js',
					SERVER: './server/index.js',
					SHIMS: './shims.js',
					ENV_PREFIX: JSON.stringify(envPrefix)
				}
			});

			// If polyfills aren't wanted then clear the file
			if (!polyfill) {
				writeFileSync(`${out}/shims.js`, '', 'utf-8');
			}
		}
	};
}