Add headers from server.headers to HTML asset responses

.changeset/shaky-experts-beg.md

@@ -0,0 +1,5 @@
+---
+"@cloudflare/vite-plugin": patch
+---
+
+Ensure that headers set via `server.headers` in the Vite config are added to HTML asset responses in development.

packages/vite-plugin-cloudflare/playground/react-spa/__tests__/server-headers/react-spa.spec.ts

@@ -0,0 +1,27 @@
+import { describe, expect, test } from "vitest";
+import { getResponse, isBuild } from "../../../__test-utils__";
+
+describe.runIf(!isBuild)(
+	"adds headers included in Vite's `server.headers` to asset responses in dev",
+	() => {
+		test("adds headers to HTML responses", async () => {
+			const response = await getResponse();
+			const headers = await response.allHeaders();
+			expect(headers).toMatchObject({
+				"custom-string": "string-value",
+				"custom-string-array": "one, two, three",
+				"custom-number": "123",
+			});
+		});
+
+		test("adds headers to non-HTML responses", async () => {
+			const response = await getResponse("/vite.svg");
+			const headers = await response.allHeaders();
+			expect(headers).toMatchObject({
+				"custom-string": "string-value",
+				"custom-string-array": "one, two, three",
+				"custom-number": "123",
+			});
+		});
+	}
+);

packages/vite-plugin-cloudflare/playground/react-spa/package.json

@@ -6,6 +6,7 @@
 		"build": "vite build --app",
 		"check:types": "tsc --build",
 		"dev": "vite dev",
+		"dev:server-headers": "vite dev -c ./vite.config.server-headers.ts",
 		"preview": "vite preview"
 	},
 	"dependencies": {

packages/vite-plugin-cloudflare/playground/react-spa/vite.config.server-headers.ts

@@ -0,0 +1,14 @@
+import { cloudflare } from "@cloudflare/vite-plugin";
+import react from "@vitejs/plugin-react";
+import { defineConfig } from "vite";
+
+export default defineConfig({
+	server: {
+		headers: {
+			"custom-string": "string-value",
+			"custom-string-array": ["one", "two", "three"],
+			"custom-number": 123,
+		},
+	},
+	plugins: [react(), cloudflare({ inspectorPort: false, persistState: false })],
+});

packages/vite-plugin-cloudflare/src/asset-workers/asset-worker.ts

@@ -1,10 +1,12 @@
 import AssetWorker from "@cloudflare/workers-shared/asset-worker";
 import { UNKNOWN_HOST } from "../shared";
 import type { Env as _Env } from "@cloudflare/workers-shared/asset-worker";
+import type { ResolvedConfig } from "vite";
 
 interface Env extends _Env {
 	__VITE_HTML_EXISTS__: Fetcher;
 	__VITE_FETCH_HTML__: Fetcher;
+	__VITE_HEADERS__: string;
 }
 
 export default class CustomAssetWorker extends AssetWorker<Env> {
@@ -13,6 +15,20 @@ export default class CustomAssetWorker extends AssetWorker<Env> {
 		const modifiedResponse = new Response(response.body, response);
 		modifiedResponse.headers.delete("ETag");
 		modifiedResponse.headers.delete("Cache-Control");
+		// Add headers set via `server.headers` in the Vite config
+		const viteHeaders = JSON.parse(
+			this.env.__VITE_HEADERS__
+		) as ResolvedConfig["server"]["headers"];
+
+		for (const [key, value] of Object.entries(viteHeaders)) {
+			if (Array.isArray(value)) {
+				for (const item of value) {
+					modifiedResponse.headers.append(key, item);
+				}
+			} else if (value !== undefined) {
+				modifiedResponse.headers.set(key, String(value));
+			}
+		}
 
 		return modifiedResponse;
 	}

packages/vite-plugin-cloudflare/src/miniflare-options.ts

@@ -292,6 +292,7 @@ export async function getDevMiniflareOptions(config: {
 			],
 			bindings: {
 				CONFIG: assetsConfig,
+				__VITE_HEADERS__: JSON.stringify(viteDevServer.config.server.headers),
 			},
 			serviceBindings: {
 				__VITE_HTML_EXISTS__: async (request) => {