next.config.js

module.exports = {
 trailingSlash: true,
 // Set the header: null value for all pages.
 headers: async () => [
    {
      source: '/*',
      headers: [
        {
          key: 'Cache-Control',
          value: 'public, max-age=0, must-revalidate',
        },
        {
          key: 'Server',
          value: 'Terrible',
        },
        {
          key: 'X-forwarded-From',
          value: 'host:8000',
        },
      ],
    },
 ],
 exportPathMap() {
    return {
      "/": { page: "/" },
      "/about": { page: "/about" },
      "/contact": { page: "/contact" },
      "/todos": { page: "/todos" },
    };
 },
 target: "server",
 distDir: ".next",
 publicRuntimeConfig: {
    // Will be available on both server and client
    publicRuntimeConfig: {
      API_URL: 'http://localhost:3000',
    },
 },
};