Next.js how to ignore a complete folder in app?

On next 13, app/api folder creates an error during build when nextConfig.output is "export".

In my project, I need different build type depending on environnement variable.

Any way to ignore "api" folder during build when "output" is "export" ?

When I run build with nextConfig.output as "export" I got following error:

Export encountered errors on following paths: /api/revalidate/route: /api/revalidate

src/app/api/revalidate/route.ts file

import { NextRequest, NextResponse } from 'next/server';
import { revalidateTag } from 'next/cache';
 
export async function GET(request: NextRequest) {
  const tag = request.nextUrl.searchParams.get('tag');
  if(tag){
    revalidateTag(tag);
  }
  return NextResponse.json({ revalidated: true, now: Date.now() });
}

Next.config.js

/** @type {import('next').NextConfig} */
const nextConfig = {
  output: process.env.NEXT_OUTPUT_MODE,
};

module.exports = nextConfig;

Reproducible repository

Here is a repository to reproduce this error https://github.com/zeckaissue/next-export-api-crash

I found a workaround with ignore-loader. But maybe there is a better way to achieve my goal with a built-in feature of next.js

Here is my updated next.config.js

/** @type {import('next').NextConfig} */
const nextConfig = {
  output: process.env.NEXT_OUTPUT_MODE,
  /**
   *
   * @param {import('webpack').Configuration} config
   * @param {import('next/dist/server/config-shared').WebpackConfigContext} context
   * @returns {import('webpack').Configuration}
   */
  webpack: (config) => {
    if (process.env.NEXT_OUTPUT_MODE !== "export" || !config.module) {
      return config;
    }
    config.module.rules?.push({
      test: /src\/app\/api/,
      loader: "ignore-loader",
    });
    return config;
  },
};

module.exports = nextConfig;