sveltejs · Rich-Harris · Jan 19, 2023 · Jan 10, 2023 · Jan 11, 2023 · Jan 11, 2023
diff --git a/.changeset/spotty-points-battle.md b/.changeset/spotty-points-battle.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': minor
+---
+
+feat: enable access to public env within app.html
diff --git a/documentation/docs/10-getting-started/30-project-structure.md b/documentation/docs/10-getting-started/30-project-structure.md
@@ -45,6 +45,7 @@ The `src` directory contains the meat of your project.
   - `%sveltekit.body%` — the markup for a rendered page. This should live inside a `<div>` or other element, rather than directly inside `<body>`, to prevent bugs caused by browser extensions injecting elements that are then destroyed by the hydration process. SvelteKit will warn you in development if this is not the case
   - `%sveltekit.assets%` — either [`paths.assets`](/docs/configuration#paths), if specified, or a relative path to [`paths.base`](/docs/configuration#paths)
   - `%sveltekit.nonce%` — a [CSP](/docs/configuration#csp) nonce for manually included links and scripts, if used
+  - `%sveltekit.env.[NAME]%` - this will be replaced at render time with the `[NAME]` environment variable, which must begin with the [`publicPrefix`](https://kit.svelte.dev/docs/configuration#env) (usually `PUBLIC_`). It will fallback to `''` if not matched.
 - `error.html` (optional) is the page that is rendered when everything else fails. It can contain the following placeholders:
   - `%sveltekit.status%` — the HTTP status
   - `%sveltekit.error.message%` — the error message

diff --git a/packages/kit/src/core/config/index.js b/packages/kit/src/core/config/index.js
@@ -9,24 +9,33 @@ import options from './options.js';
  * @param {string} cwd
  * @param {import('types').ValidatedConfig} config
  */
-export function load_template(cwd, config) {
-	const { appTemplate } = config.kit.files;
-	const relative = path.relative(cwd, appTemplate);
-
-	if (fs.existsSync(appTemplate)) {
-		const contents = fs.readFileSync(appTemplate, 'utf8');
-
-		const expected_tags = ['%sveltekit.head%', '%sveltekit.body%'];
-		expected_tags.forEach((tag) => {
-			if (contents.indexOf(tag) === -1) {
-				throw new Error(`${relative} is missing ${tag}`);
-			}
-		});
-	} else {
+export function load_template(cwd, { kit }) {
+	const { env, files } = kit;
+
+	const relative = path.relative(cwd, files.appTemplate);
+
+	if (!fs.existsSync(files.appTemplate)) {
 		throw new Error(`${relative} does not exist`);
 	}
 
-	return fs.readFileSync(appTemplate, 'utf-8');
+	const contents = fs.readFileSync(files.appTemplate, 'utf8');
+
+	const expected_tags = ['%sveltekit.head%', '%sveltekit.body%'];
+	expected_tags.forEach((tag) => {
+		if (contents.indexOf(tag) === -1) {
+			throw new Error(`${relative} is missing ${tag}`);
+		}
+	});
+
+	for (const match of contents.matchAll(/%sveltekit\.env\.([^%]+)%/g)) {
+		if (!match[1].startsWith(env.publicPrefix)) {
+			throw new Error(
+				`Environment variables in ${relative} must start with ${env.publicPrefix} (saw %sveltekit.env.${match[1]}%)`
+			);
+		}
+	}
+
+	return contents;
 }
 
 /**

diff --git a/packages/kit/src/core/sync/write_server.js b/packages/kit/src/core/sync/write_server.js
@@ -38,11 +38,15 @@ export const options = {
 	root,
 	service_worker: ${has_service_worker},
 	templates: {
-		app: ({ head, body, assets, nonce }) => ${s(template)
+		app: ({ head, body, assets, nonce, env }) => ${s(template)
 			.replace('%sveltekit.head%', '" + head + "')
 			.replace('%sveltekit.body%', '" + body + "')
 			.replace(/%sveltekit\.assets%/g, '" + assets + "')
-			.replace(/%sveltekit\.nonce%/g, '" + nonce + "')},
+			.replace(/%sveltekit\.nonce%/g, '" + nonce + "')
+			.replace(
+				/%sveltekit\.env\.([^%]+)%/g,
+				(_match, capture) => `" + (env[${s(capture)}] ?? "") + "`
+			)},
 		error: ({ status, message }) => ${s(error_page)
 			.replace(/%sveltekit\.status%/g, '" + status + "')
 			.replace(/%sveltekit\.error\.message%/g, '" + message + "')}

diff --git a/packages/kit/src/exports/vite/dev/index.js b/packages/kit/src/exports/vite/dev/index.js
@@ -73,8 +73,7 @@ export async function dev(vite, vite_config, svelte_config) {
 		} catch (error) {
 			manifest_error = /** @type {Error} */ (error);
 
-			console.error(colors.bold().red('Invalid routes'));
-			console.error(error);
+			console.error(colors.bold().red(manifest_error.message));
 			vite.ws.send({
 				type: 'error',
 				err: {
@@ -444,8 +443,7 @@ export async function dev(vite, vite_config, svelte_config) {
 				}
 
 				if (manifest_error) {
-					console.error(colors.bold().red('Invalid routes'));
-					console.error(manifest_error);
+					console.error(colors.bold().red(manifest_error.message));
 
 					const error_page = load_error_page(svelte_config);
 

diff --git a/packages/kit/src/runtime/env-public.js b/packages/kit/src/runtime/env-public.js
@@ -1,3 +1,4 @@
+/** @type {Record<string, string>} */
 export let env = {};
 
 /** @type {(environment: Record<string, string>) => void} */

diff --git a/packages/kit/src/runtime/server/page/render.js b/packages/kit/src/runtime/server/page/render.js
@@ -366,7 +366,8 @@ export async function render_response({
 		head,
 		body,
 		assets: resolved_assets,
-		nonce: /** @type {string} */ (csp.nonce)
+		nonce: /** @type {string} */ (csp.nonce),
+		env
 	});
 
 	// TODO flush chunks as early as we can

diff --git a/packages/kit/test/apps/basics/.env b/packages/kit/test/apps/basics/.env
@@ -3,3 +3,5 @@ PRIVATE_DYNAMIC="accessible to server-side code/evaluated at run time"
 
 PUBLIC_STATIC="accessible anywhere/replaced at build time"
 PUBLIC_DYNAMIC="accessible anywhere/evaluated at run time"
+
+PUBLIC_THEME="groovy"
diff --git a/packages/kit/test/apps/basics/src/app.html b/packages/kit/test/apps/basics/src/app.html
@@ -7,7 +7,7 @@
 		<meta name="transform-page" content="__REPLACEME__" />
 		%sveltekit.head%
 	</head>
-	<body>
+	<body class="%sveltekit.env.PUBLIC_THEME%">
 		<div>%sveltekit.body%</div>
 		<a href="/routing/link-outside-app-target/target">outside app target</a>
 	</body>

diff --git a/packages/kit/test/apps/basics/test/client.test.js b/packages/kit/test/apps/basics/test/client.test.js
@@ -600,3 +600,10 @@ test.describe('Content negotiation', () => {
 		await expect(page.locator('[data-testid="form-result"]')).toHaveText('form.submitted: true');
 	});
 });
+
+test.describe('env in app.html', () => {
+	test('can access public env', async ({ page }) => {
+		await page.goto('/');
+		expect(await page.locator('body').getAttribute('class')).toContain('groovy');
+	});
+});
diff --git a/packages/kit/types/internal.d.ts b/packages/kit/types/internal.d.ts
@@ -306,7 +306,13 @@ export interface SSROptions {
 	root: SSRComponent['default'];
 	service_worker: boolean;
 	templates: {
-		app(values: { head: string; body: string; assets: string; nonce: string }): string;
+		app(values: {
+			head: string;
+			body: string;
+			assets: string;
+			nonce: string;
+			env: Record<string, string>;
+		}): string;
 		error(values: { message: string; status: number }): string;
 	};
 }
Original file line number	Diff line number	Diff line change
Expand Up		@@ -3,3 +3,5 @@ PRIVATE_DYNAMIC="accessible to server-side code/evaluated at run time"

		PUBLIC_STATIC="accessible anywhere/replaced at build time"
		PUBLIC_DYNAMIC="accessible anywhere/evaluated at run time"

		PUBLIC_THEME="groovy"