fix: keep the Docker build within Node's default heap #1510

lib/__tests__/next-config-build-worker.test.ts

@@ -0,0 +1,11 @@
+import { describe, expect, it } from 'vitest';
+import config from '../../next.config';
+
+describe('webpack build worker', () => {
+  // Next turns the workers off for a config with a webpack hook unless the
+  // option is set, and the Docker build then runs out of heap (#1510).
+  it('stays on although next-intl adds a webpack hook', () => {
+    expect(config.webpack).toBeTypeOf('function');
+    expect(config.experimental?.webpackBuildWorker).toBe(true);
+  });
+});

next.config.ts

@@ -102,6 +102,13 @@ const nextConfig: NextConfig = {
   typescript: {
     tsconfigPath: "tsconfig.build.json",
   },
+  // next-intl's plugin adds a webpack hook, and with one Next runs the client,
+  // server and edge compilers in its main process on one heap, which outgrew
+  // Node's default limit of about 2.2 GB (#1510). In workers each compiler has
+  // its own heap, freed when it finishes. Turbopack builds don't read this.
+  experimental: {
+    webpackBuildWorker: true,
+  },
   // No proxyClientMaxBodySize: Next copies every body proxy.ts runs for up to
   // that size before routing, so it stays at the 10 MB default. The routes
   // that take bigger uploads (WOPI saves, WebDAV, /api/plugin-proxy) are left