From 318cdd70a97468fc13befbfc1a925b1ccf9575c6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6n=20Limell?= <bjon@users.noreply.github.com>
Date: Wed, 16 Jun 2021 15:27:30 +0200
Subject: [PATCH] Only cache content in /_app (#1416)

---
 .changeset/strong-files-obey.md     |  5 +++++
 packages/adapter-node/index.js      |  9 +++++---
 packages/adapter-node/src/server.js | 34 ++++++++++++++++++++++++-----
 3 files changed, 39 insertions(+), 9 deletions(-)
 create mode 100644 .changeset/strong-files-obey.md

diff --git a/.changeset/strong-files-obey.md b/.changeset/strong-files-obey.md
new file mode 100644
index 000000000000..fd6e6884a8a5
--- /dev/null
+++ b/.changeset/strong-files-obey.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-node': patch
+---
+
+Only cache files in config.kit.appDir
diff --git a/packages/adapter-node/index.js b/packages/adapter-node/index.js
index 5643b87b3dce..3a0a36309205 100644
--- a/packages/adapter-node/index.js
+++ b/packages/adapter-node/index.js
@@ -1,7 +1,7 @@
+import esbuild from 'esbuild';
 import { readFileSync } from 'fs';
 import { join } from 'path';
 import { fileURLToPath } from 'url';
-import esbuild from 'esbuild';
 
 /**
  * @param {{
@@ -13,7 +13,7 @@ export default function ({ out = 'build' } = {}) {
 	const adapter = {
 		name: '@sveltejs/adapter-node',
 
-		async adapt({ utils }) {
+		async adapt({ utils, config }) {
 			utils.log.minor('Copying assets');
 			const static_directory = join(out, 'assets');
 			utils.copy_client_files(static_directory);
@@ -29,7 +29,10 @@ export default function ({ out = 'build' } = {}) {
 				external: Object.keys(JSON.parse(readFileSync('package.json', 'utf8')).dependencies || {}),
 				format: 'esm',
 				platform: 'node',
-				target: 'node12'
+				target: 'node12',
+				define: {
+					esbuild_app_dir: '"' + config.kit.appDir + '"'
+				}
 			});
 
 			utils.log.minor('Prerendering static pages');
diff --git a/packages/adapter-node/src/server.js b/packages/adapter-node/src/server.js
index ce8cb5f20f4c..26c2d099d7ed 100644
--- a/packages/adapter-node/src/server.js
+++ b/packages/adapter-node/src/server.js
@@ -1,11 +1,11 @@
+import '@sveltejs/kit/install-fetch'; // eslint-disable-line import/no-unresolved
+import { getRawBody } from '@sveltejs/kit/node'; // eslint-disable-line import/no-unresolved
+import compression from 'compression';
 import fs from 'fs';
 import { dirname, join } from 'path';
-import { fileURLToPath } from 'url';
-import compression from 'compression';
 import polka from 'polka';
 import sirv from 'sirv';
-import { getRawBody } from '@sveltejs/kit/node'; // eslint-disable-line import/no-unresolved
-import '@sveltejs/kit/install-fetch'; // eslint-disable-line import/no-unresolved
+import { fileURLToPath } from 'url';
 
 // App is a dynamic file built from the application layer.
 
@@ -23,14 +23,36 @@ export function createServer({ render }) {
 			maxAge: 0
 		});
 
+	const immutable_path = (pathname) => {
+		// eslint-disable-next-line no-undef
+		let app_dir = esbuild_app_dir;
+
+		// hard to tell when app_dir is mixed with static
+		if (app_dir === '/') {
+			return false;
+		}
+
+		if (app_dir.startsWith('/')) {
+			app_dir = app_dir.slice(1);
+		}
+		if (app_dir.endsWith('/')) {
+			app_dir = app_dir.slice(0, -1);
+		}
+
+		return pathname.startsWith(`/${app_dir}/`);
+	};
+
 	const prerendered_handler = fs.existsSync(paths.prerendered)
 		? mutable(paths.prerendered)
 		: noop_handler;
 
 	const assets_handler = fs.existsSync(paths.assets)
 		? sirv(paths.assets, {
-				maxAge: 31536000,
-				immutable: true,
+				setHeaders: (res, pathname, stats) => {
+					if (immutable_path(pathname)) {
+						res.setHeader('cache-control', 'public, max-age=31536000, immutable');
+					}
+				},
 				gzip: true,
 				brotli: true
 		  })