feat(netlify): set cache headers (#326)

.changeset/ten-chicken-provide.md

@@ -0,0 +1,5 @@
+---
+'@astrojs/netlify': minor
+---
+
+Sets immutable cache headers for static assets

packages/netlify/src/index.ts

@@ -112,13 +112,25 @@ async function writeNetlifyFrameworkConfig(config: AstroConfig, logger: AstroInt
 			.filter(Boolean as unknown as (pattern?: string) => pattern is string)
 	);
 
+	const headers = config.build.assetsPrefix
+		? undefined
+		: [
+				{
+					for: `${config.base}${config.base.endsWith('/') ? '' : '/'}${config.build.assets}/*`,
+					values: {
+						'Cache-Control': 'public, max-age=31536000, immutable',
+					},
+				},
+			];
+
 	// See https://docs.netlify.com/image-cdn/create-integration/
 	const deployConfigDir = new URL('.netlify/v1/', config.root);
 	await mkdir(deployConfigDir, { recursive: true });
 	await writeFile(
 		new URL('./config.json', deployConfigDir),
 		JSON.stringify({
 			images: { remote_images: remoteImages },
+			headers,
 		})
 	);
 }
@@ -432,9 +444,7 @@ export default function netlifyIntegration(
 				rootDir = config.root;
 				_config = config;
 
-				if (config.image?.domains?.length || config.image?.remotePatterns?.length) {
-					await writeNetlifyFrameworkConfig(config, logger);
-				}
+				await writeNetlifyFrameworkConfig(config, logger);
 
 				const edgeMiddleware = integrationConfig?.edgeMiddleware ?? false;
 

packages/netlify/test/static/fixtures/redirects/astro.config.mjs

@@ -2,10 +2,9 @@ import netlify from '@astrojs/netlify';
 import { defineConfig } from 'astro/config';
 
 export default defineConfig({
-  output: 'static',
-  adapter: netlify(),
-  site: `http://example.com`,
-  site: `http://example.com`,
+	output: 'static',
+	adapter: netlify(),
+	site: "http://example.com",
 	redirects: {
 		'/other': '/',
 		'/two': {
@@ -14,4 +13,4 @@ export default defineConfig({
 		},
 		'/blog/[...slug]': '/team/articles/[...slug]',
 	},
-});
+});

packages/netlify/test/static/headers.test.js

@@ -0,0 +1,25 @@
+import * as assert from 'node:assert/strict';
+import { before, describe, it } from 'node:test';
+import { loadFixture } from '@astrojs/test-utils';
+
+describe('SSG - headers', () => {
+	let fixture;
+
+	before(async () => {
+		fixture = await loadFixture({ root: new URL('./fixtures/redirects/', import.meta.url) });
+		await fixture.build();
+	});
+
+	it('Generates headers for static assets', async () => {
+		const config = await fixture.readFile('../.netlify/v1/config.json');
+		const headers = JSON.parse(config).headers;
+		assert.deepEqual(headers, [
+			{
+				for: '/_astro/*',
+				values: {
+					'Cache-Control': 'public, max-age=31536000, immutable',
+				},
+			},
+		]);
+	});
+});