Conditional asset inclusion based on build configuration

[davetapley]

Goals

When doing next build (aka output: "export"), I would like to only include assets in public/ (or similar) which are required, based on an env var.

Non-Goals

Server side rendering

Background

My current setup works like this:

I have a sites.json which defines different 'sites' for different 'domains'.
Then I can pass the domain in as an env var which populates a generateStaticParams, loosely like this:

// sites.ts
import _data from "../sites.json";
const domains = _data as Domains;
export const domain = process.env.domain;
export const sites = domains[domain];

// app/[site]/page.tsx
import { sites } from "./sites";

export async function generateStaticParams() {
  const params = Object.keys(sites).map((site) => {
    return { site };
  });
  return params;
}

export default async function Page({ params }: { params: PageParams }) {
  const { site } = params;
  const siteData = sites[site];

It works great but for one issue: Everything I put in public/ is written to out/ regardless of the domain env var.

That makes sense, but I can't think of a way to have only the required files written.

Proposal

Not sure, but happy to contribute 🤪