The private network is not available during build time.

Oh dear, so I have to make my Strapi address public?

Isn't there an alternative to use only the private network with Next.js in the build?

Using the New Builder solved the problem.

Don't forget to add :: to HOST and remove URL env variable if you plan to use only private networking.

Please know that we can not currently provide support when using the new builder, it's in an unmaintained Beta state right now.

We strongly recommend you not to use it, simply do not call a private domain during build, do it during runtime.

Thanks for your reply. But with NextJS we need to fetch at build time for static generation.

We don’t want to made our api public, how could we fix this without the new builder ? Do you have a workaround ?

The new builder is in beta, but do you think it will be out of beta soon?

I've configured my Strapi to be publicly accessible only via Cloudflare Tunnels (Zero-Trust) to get around this New Builder problem.

I created a Service Token on Cloudflare Tunnels that I add to my Next.js fetch function to allow only calls from my Next.js application to Strapi and nothing else. I'm always in favor of privatizing an application and making it accessible only on a private network when there's no need for public use.

I think I've found a way to change environment variables dynamically at buildtime and runtime on Next.js.

For example, with the env variable NEXT_PHASE, which is given to me natively by Next.js, the env lets me know which phase I'm in (buildtime or runtime), here's an example:

import {
  PHASE_PRODUCTION_BUILD,
} from “next/constants”;

 console.log(
      "Building Next app now ?",
      process.env.NEXT_PHASE === PHASE_PRODUCTION_BUILD,
    );

Depending on the NEXT_PHASE, I can then switch between the Public Strapi URL via Cloudflare Tunnel at buildtime, and the Private Strapi URL at runtime to avoid Network Egress fees with Railway.

Perhaps it would be interesting to document this usecase in the official Railway doc, as I think quite a few of us have this use case with Next.js building scenario ?

Personally I think this solution is far more complex than it needs to be, simply don't call strapi at build time, call it during runtime before starting the app.

Personally I think this solution is far more complex than it needs to be, simply don't call strapi at build time, call it during runtime before starting the app.

Yes, but I need to generate static pages at build time... so Next.js call strapi at build because my app pages have strapi calls

I can't remove the main feature of Next.js for just Railway 🥹

https://nextjs.org/docs/pages/building-your-application/rendering/server-side-rendering SSR

You can build during runtime.

Or do dynamic SSR when needed with cache.

did you have a tutorial for that ?

It wouldn't be specific to the Railway platform so we don't have a tutorial.