fix: Bail out & skip plugin during Vite's SSR builds

package.json

@@ -37,14 +37,15 @@
     "stack-trace": "^1.0.0-pre2"
   },
   "devDependencies": {
+    "@cloudflare/vite-plugin": "^1.0.8",
     "@types/node": "^20.11.16",
     "dedent": "^1.5.3",
     "magic-string": "^0.30.6",
     "prettier": "^2.8.8",
     "prettier-config-rschristian": "^0.1.1",
     "tmp-promise": "^3.0.3",
     "uvu": "^0.5.6",
-    "vite": "^5.0.12"
+    "vite": "^6.3.1"
   },
   "prettier": "prettier-config-rschristian"
 }

src/plugins/prerender-plugin.js

@@ -74,6 +74,7 @@ function serializeElement(element) {
 export function prerenderPlugin({ prerenderScript, renderTarget, additionalPrerenderRoutes } = {}) {
     let viteConfig = {};
     let userEnabledSourceMaps;
+    let ssrBuild = false;
 
     /** @type {import('./types.d.ts').PrerenderedRoute[]} */
     let routes = [];
@@ -124,9 +125,19 @@ export function prerenderPlugin({ prerenderScript, renderTarget, additionalPrere
         name: 'vite-prerender-plugin',
         apply: 'build',
         enforce: 'post',
+        applyToEnvironment(environment) {
+            return environment.name == 'client';
+        },
         // Vite is pretty inconsistent with how it resolves config options, both
         // hooks are needed to set their respective options. ¯\_(ツ)_/¯
         config(config) {
+            // Only required for Vite 5 and older. In 6+, this is handled by the
+            // Environment API (`applyToEnvironment`)
+            if (config.build?.ssr) {
+                ssrBuild = true
+                return;
+            }
+
             userEnabledSourceMaps = !!config.build?.sourcemap;
 
             if (!config.customLogger) {
@@ -161,6 +172,7 @@ export function prerenderPlugin({ prerenderScript, renderTarget, additionalPrere
             config.build.sourcemap = true;
         },
         configResolved(config) {
+            if (ssrBuild) return;
             // We're only going to alter the chunking behavior in the default cases, where the user and/or
             // other plugins haven't already configured this. It'd be impossible to avoid breakages otherwise.
             if (
@@ -181,7 +193,7 @@ export function prerenderPlugin({ prerenderScript, renderTarget, additionalPrere
             viteConfig = config;
         },
         async options(opts) {
-            if (!opts.input) return;
+            if (ssrBuild || !opts.input) return;
             if (!prerenderScript) {
                 prerenderScript = await getPrerenderScriptFromHTML(opts.input);
             }
@@ -197,6 +209,7 @@ export function prerenderPlugin({ prerenderScript, renderTarget, additionalPrere
         },
         // Injects window checks into Vite's preload helper & modulepreload polyfill
         transform(code, id) {
+            if (ssrBuild) return;
             if (id.includes(preloadHelperId)) {
                 // Injects a window check into Vite's preload helper, instantly resolving
                 // the module rather than attempting to add a <link> to the document.
@@ -238,6 +251,7 @@ export function prerenderPlugin({ prerenderScript, renderTarget, additionalPrere
             }
         },
         async generateBundle(_opts, bundle) {
+            if (ssrBuild) return;
             // @ts-ignore
             globalThis.location = {};
             // @ts-ignore

tests/environments.test.js

@@ -0,0 +1,44 @@
+import { test } from 'uvu';
+import * as assert from 'uvu/assert';
+
+import { setupTest, teardownTest, loadFixture, viteBuild, viteBuildCli } from './lib/lifecycle.js';
+
+let env;
+test.before.each(async () => {
+    env = await setupTest();
+});
+
+test.after.each(async () => {
+    await teardownTest(env);
+});
+
+test('Should skip plugin during SSR build', async () => {
+    await loadFixture('environments/ssr', env);
+
+    let message = '';
+    try {
+        await viteBuild(env.tmp.path);
+    } catch (error) {
+        message = error.message;
+    }
+
+    assert.match(message, '');
+});
+
+test('Should skip plugin during SSR build (CLI)', async () => {
+    await loadFixture('simple', env);
+    const output = await viteBuildCli(env.tmp.path, ['--ssr', 'src/index.js']);
+    await output.done;
+
+    assert.equal(output.stderr, []);
+});
+
+test('Should skip plugin during non-client environment build (Cloudflare plugin)', async () => {
+    await loadFixture('environments/cloudflare', env);
+    const output = await viteBuildCli(env.tmp.path);
+    await output.done;
+
+    assert.equal(output.stderr, []);
+});
+
+test.run();

tests/fixtures/environments/cloudflare/index.html

@@ -0,0 +1,9 @@
+<!DOCTYPE html>
+<html lang="en">
+    <head>
+        <meta charset="UTF-8" />
+    </head>
+    <body>
+        <script prerender type="module" src="/src/index.js"></script>
+    </body>
+</html>

tests/fixtures/environments/cloudflare/src/index.js

@@ -0,0 +1,3 @@
+export async function prerender() {
+    return `<h1>Simple Test Result</h1>`;
+}

tests/fixtures/environments/cloudflare/src/server.js

@@ -0,0 +1 @@
+console.log("Server is running...");

tests/fixtures/environments/cloudflare/vite.config.js

@@ -0,0 +1,9 @@
+import { defineConfig } from 'vite';
+import { vitePrerenderPlugin } from 'vite-prerender-plugin';
+import { cloudflare } from '@cloudflare/vite-plugin';
+
+console.log('Config is used');
+
+export default defineConfig({
+    plugins: [cloudflare(), vitePrerenderPlugin()],
+});

tests/fixtures/environments/cloudflare/wrangler.toml

@@ -0,0 +1,4 @@
+name = "my-worker"
+compatibility_date = "2023-03-01"
+
+main = "src/server.js"

tests/fixtures/environments/ssr/index.html

@@ -0,0 +1,9 @@
+<!DOCTYPE html>
+<html lang="en">
+    <head>
+        <meta charset="UTF-8" />
+    </head>
+    <body>
+        <script prerender type="module" src="/src/index.js"></script>
+    </body>
+</html>

tests/fixtures/environments/ssr/src/index.js

@@ -0,0 +1,3 @@
+export async function prerender() {
+    return `<h1>Simple Test Result</h1>`;
+}

tests/fixtures/environments/ssr/vite.config.js

@@ -0,0 +1,12 @@
+import { defineConfig } from 'vite';
+import { vitePrerenderPlugin } from 'vite-prerender-plugin';
+
+export default defineConfig({
+    build: {
+        ssr: true,
+        rollupOptions: {
+            input: 'src/index.js'
+        }
+    },
+    plugins: [vitePrerenderPlugin()],
+});

tests/index.test.js

@@ -90,7 +90,6 @@ test('Should support custom output filenames', async () => {
             plugins: [vitePrerenderPlugin()],
         });
     `);
-    await viteBuild(env.tmp.path);
 
     let message = '';
     try {

tests/lib/lifecycle.js

@@ -50,9 +50,10 @@ export async function viteBuild(cwd) {
 
 /**
  * @param {string} cwd
+ * @param {string[]} flags
  */
-export async function viteBuildCli(cwd) {
-    const child = childProcess.spawn('node', ['node_modules/vite/bin/vite.js', 'build'], {
+export async function viteBuildCli(cwd, flags = []) {
+    const child = childProcess.spawn('node', ['node_modules/vite/bin/vite.js', 'build', ...flags], {
         cwd,
     });
 

tests/lib/utils.js

@@ -35,6 +35,9 @@ export async function copyDependencies(cwd) {
     await copyNodeModule('source-map');
     await copyNodeModule('stack-trace');
     await copyNodeModule('kolorist');
+
+    // Dependencies used by tests
+    await copyNodeModule('@cloudflare/vite-plugin');
 }
 
 /**