[feat] use Netlify internal functions directory for generated functions (#2113)

Author: ascorbic

.changeset/brave-clouds-protect.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-netlify': patch
+---
+
+Deploy generated Netlify entrypoint to the internal functions directory. This allows it to co-exist with other Netlify functions.

.gitignore

@@ -11,3 +11,4 @@ yarn.lock
 .svelte-kit
 .cloudflare
 .pnpm-debug.log
+.netlify

examples/hn.svelte.dev/.gitignore

@@ -2,4 +2,4 @@
 node_modules
 /.svelte
 /build
-/functions
+/.netlify/functions*

examples/hn.svelte.dev/.netlify/netlify-plugin-pnpm/index.js

@@ -1,8 +1,9 @@
-export default {
+module.exports = {
   onPreBuild: async ({ utils: { build, run } }) => {
     try {
       await run.command("npm install -g pnpm")
-      await run.command("pnpm install")
+      await run.command("pnpm -w install")
+      await run.command("pnpm -w build")
     } catch (error) {
       return build.failBuild(error)
     }

examples/hn.svelte.dev/.netlify/netlify-plugin-pnpm/package.json

@@ -0,0 +1 @@
+{"type":"commonjs"}

examples/hn.svelte.dev/netlify.toml

@@ -1,7 +1,6 @@
 [build]
   command = "npm run build"
-  publish = ".svelte-kit/netlify/build/"
-  functions = ".svelte-kit/netlify/functions/"
+  publish = "build"
 
 [build.environment]
   NPM_FLAGS="--prefix=/dev/null"

packages/adapter-netlify/README.md

@@ -27,15 +27,16 @@ export default {
 };
 ```
 
-Then, make sure you have a [netlify.toml](https://docs.netlify.com/configure-builds/file-based-configuration) file in the project root. This will determine where to write static assets and functions to based on the `build.publish` and `build.functions` settings, as per this sample configuration:
+Then, make sure you have a [netlify.toml](https://docs.netlify.com/configure-builds/file-based-configuration) file in the project root. This will determine where to write static assets based on the `build.publish` settings, as per this sample configuration:
 
 ```toml
 [build]
   command = "npm run build"
-  publish = "build/publish/"
-  functions = "build/functions/"
+  publish = "build"
 ```
 
+If the `netlify.toml` file or the `build.publish` value is missing, a default value of `"build"` will be used. Note that if you have set the publish directory in the Netlify UI to something else then you will need to set it in `netlify.toml` too, or use the default value of `"build"`.
+
 ## Netlify alternatives to SvelteKit functionality
 
 You may build your app using functionality provided directly by SvelteKit without relying on any Netlify functionality. Using the SvelteKit versions of these features will allow them to be used in dev mode, tested with integration tests, and to work with other adapters should you ever decide to switch away from Netlify. However, in some scenarios you may find it beneficial to use the Netlify versions of these features. One example would be if you're migrating an app that's already hosted on Netlify to SvelteKit.
@@ -53,6 +54,20 @@ During compilation a required "catch all" redirect rule is automatically appende
 2. Netlify's build bot parses your HTML files at deploy time, which means your form must be [prerendered](https://kit.svelte.dev/docs#ssr-and-javascript-prerender) as HTML. You can either add `export const prerender = true` to your `contact.svelte` to prerender just that page or set the `kit.prerender.force: true` option to prerender all pages.
 3. If your Netlify form has a [custom success message](https://docs.netlify.com/forms/setup/#success-messages) like `<form netlify ... action="/success">` then ensure the corresponding `/routes/success.svelte` exists and is prerendered.
 
+### Using Netlify Functions
+
+[Netlify Functions](https://docs.netlify.com/functions/overview/) can be used alongside your SvelteKit routes. If you would like to add them to your site, you should create a directory for them and add the configuration to your `netlify.toml` file. For example:
+
+```toml
+[build]
+  command = "npm run build"
+  publish = "build"
+
+[functions]
+  directory = "functions"
+  node_bundler = "esbuild"
+```
+
 ## Advanced Configuration
 
 ### esbuild
@@ -77,7 +92,8 @@ The default options for this version are as follows:
 ```js
 {
 	entryPoints: ['.svelte-kit/netlify/entry.js'],
-	outfile: `pathToFunctionsFolder/render/index.js`,
+	// This is Netlify's internal functions directory, not the one for user functions.
+	outfile: '.netlify/functions-internal/__render.js',
 	bundle: true,
 	inject: ['pathTo/shims.js'],
 	platform: 'node'

packages/adapter-netlify/index.js

@@ -1,5 +1,5 @@
 import { appendFileSync, existsSync, readFileSync, writeFileSync } from 'fs';
-import { join } from 'path';
+import { join, resolve } from 'path';
 import { fileURLToPath } from 'url';
 import esbuild from 'esbuild';
 import toml from '@iarna/toml';
@@ -19,10 +19,12 @@ export default function (options) {
 		name: '@sveltejs/adapter-netlify',
 
 		async adapt({ utils }) {
-			const { publish, functions } = validate_config().build;
+			// "build" is the default publish directory when Netlify detects SvelteKit
+			const publish = get_publish_directory(utils) || 'build';
+
+			utils.log.minor(`Publishing to "${publish}"`);
 
 			utils.rimraf(publish);
-			utils.rimraf(functions);
 
 			const files = fileURLToPath(new URL('./files', import.meta.url));
 
@@ -32,7 +34,9 @@ export default function (options) {
 			/** @type {BuildOptions} */
 			const defaultOptions = {
 				entryPoints: ['.svelte-kit/netlify/entry.js'],
-				outfile: join(functions, 'render/index.js'),
+				// Any functions in ".netlify/functions-internal" are bundled in addition to user-defined Netlify functions.
+				// See https://github.com/netlify/build/pull/3213 for more details
+				outfile: '.netlify/functions-internal/__render.js',
 				bundle: true,
 				inject: [join(files, 'shims.js')],
 				platform: 'node'
@@ -43,9 +47,9 @@ export default function (options) {
 
 			await esbuild.build(buildOptions);
 
-			writeFileSync(join(functions, 'package.json'), JSON.stringify({ type: 'commonjs' }));
+			writeFileSync(join('.netlify', 'package.json'), JSON.stringify({ type: 'commonjs' }));
 
-			utils.log.info('Prerendering static pages...');
+			utils.log.minor('Prerendering static pages...');
 			await utils.prerender({
 				dest: publish
 			});
@@ -55,16 +59,21 @@ export default function (options) {
 			utils.copy_client_files(publish);
 
 			utils.log.minor('Writing redirects...');
-			utils.copy('_redirects', `${publish}/_redirects`);
-			appendFileSync(`${publish}/_redirects`, '\n\n/* /.netlify/functions/render 200');
+
+			const redirectPath = join(publish, '_redirects');
+			utils.copy('_redirects', redirectPath);
+			appendFileSync(redirectPath, '\n\n/* /.netlify/functions/__render 200');
 		}
 	};
 
 	return adapter;
 }
-
-function validate_config() {
+/**
+ * @param {import('@sveltejs/kit').AdapterUtils} utils
+ **/
+function get_publish_directory(utils) {
 	if (existsSync('netlify.toml')) {
+		/** @type {{ build?: { publish?: string }} & toml.JsonMap } */
 		let netlify_config;
 
 		try {
@@ -74,23 +83,25 @@ function validate_config() {
 			throw err;
 		}
 
-		if (!netlify_config.build || !netlify_config.build.publish || !netlify_config.build.functions) {
-			throw new Error(
-				'You must specify build.publish and build.functions in netlify.toml. Consult https://github.com/sveltejs/kit/tree/master/packages/adapter-netlify#configuration'
-			);
+		if (!netlify_config.build || !netlify_config.build.publish) {
+			utils.log.warn('No publish directory specified in netlify.toml, using default');
+			return;
 		}
 
 		if (netlify_config.redirects) {
 			throw new Error(
 				"Redirects are not supported in netlify.toml. Use _redirects instead. For more details consult the readme's troubleshooting section."
 			);
 		}
-
-		return netlify_config;
+		if (resolve(netlify_config.build.publish) === process.cwd()) {
+			throw new Error(
+				'The publish directory cannot be set to the site root. Please change it to another value such as "build" in netlify.toml.'
+			);
+		}
+		return netlify_config.build.publish;
 	}
 
-	// TODO offer to create one?
-	throw new Error(
-		'Missing a netlify.toml file. Consult https://github.com/sveltejs/kit/tree/master/packages/adapter-netlify#configuration'
+	utils.log.warn(
+		'No netlify.toml found. Using default publish directory. Consult https://github.com/sveltejs/kit/tree/master/packages/adapter-netlify#configuration for more details '
 	);
 }

packages/create-svelte/templates/default/netlify.toml

@@ -1,4 +1,3 @@
 [build]
   command = "npm run build"
-  publish = ".svelte-kit/netlify/build/"
-  functions = ".svelte-kit/netlify/functions/"
+  publish = "build"