Skip now.json without legacy static configuration

.changeset/modern-now-configuration.md

@@ -0,0 +1,5 @@
+---
+'serve': patch
+---
+
+Ignore now.json without legacy static-serving configuration instead of crashing at startup.

readme.md

@@ -58,6 +58,9 @@ Now you understand how the package works! :tada:
 
 ## Configuration
 
+A `now.json` file without a legacy `now.static` section is ignored when
+looking for static-serving configuration.
+
 To customize `serve`'s behavior, create a `serve.json` file in the public folder and insert any of [these properties](https://github.com/vercel/serve-handler#options).
 
 ## API

source/utilities/config.ts

@@ -61,7 +61,7 @@ export const loadConfiguration = async (
       static?: Partial<Configuration>;
     }
     interface NowConfigurationFile {
-      now: { static?: Partial<Configuration> };
+      now?: { static?: Partial<Configuration> };
     }
     type ParseableConfiguration =
       | ServeConfigurationFile
@@ -87,7 +87,7 @@ export const loadConfiguration = async (
     // Check if any of these files have a serve specific section.
     if (file === 'now.json') {
       parsedJson = parsedJson as NowConfigurationFile;
-      parsedJson = parsedJson.now.static;
+      parsedJson = parsedJson.now?.static;
     } else if (file === 'package.json') {
       parsedJson = parsedJson as ManifestConfigurationFile;
       parsedJson = parsedJson.static;

tests/config-legacy.test.ts

@@ -0,0 +1,51 @@
+import { mkdtemp, writeFile, rm } from 'node:fs/promises';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { expect, test } from 'vitest';
+import { loadConfiguration } from '../source/utilities/config.js';
+
+test('a modern now.json without a legacy static section does not break static serving', async () => {
+  const directory = await mkdtemp(join(tmpdir(), 'serve-now-'));
+  try {
+    await writeFile(
+      join(directory, 'now.json'),
+      JSON.stringify({ version: 2 }),
+    );
+    const config = await loadConfiguration(directory, directory, {});
+    expect(config.public).toBe('');
+    expect(config.etag).toBe(true);
+  } finally {
+    await rm(directory, { recursive: true, force: true });
+  }
+});
+test('a legacy now.static section is still loaded', async () => {
+  const directory = await mkdtemp(join(tmpdir(), 'serve-now-'));
+  try {
+    await writeFile(
+      join(directory, 'now.json'),
+      JSON.stringify({ now: { static: { cleanUrls: false } } }),
+    );
+    const config = await loadConfiguration(directory, directory, {});
+    expect(config.cleanUrls).toBe(false);
+  } finally {
+    await rm(directory, { recursive: true, force: true });
+  }
+});
+
+test('a modern now.json falls through to package.json static settings', async () => {
+  const directory = await mkdtemp(join(tmpdir(), 'serve-now-'));
+  try {
+    await writeFile(
+      join(directory, 'now.json'),
+      JSON.stringify({ version: 2 }),
+    );
+    await writeFile(
+      join(directory, 'package.json'),
+      JSON.stringify({ static: { cleanUrls: false } }),
+    );
+    const config = await loadConfiguration(directory, directory, {});
+    expect(config.cleanUrls).toBe(false);
+  } finally {
+    await rm(directory, { recursive: true, force: true });
+  }
+});