question: how to use env vars in next.config ?

[tresorama]

I need env vars to conditionally define properties in the nextConfig.

Without t3-env I'm doing this

// in next.config.mjs

/** @type {import('next').NextConfig} */
const nextConfig = {
  ...(process.env.NEXT_PUBLIC_APP_BUILD_MODE === 'static-export' && ({
    output: 'export',
  })),
  ...(process.env.NEXT_PUBLIC_APP_BUILD_MODE === 'api' && ({
    async headers() {
      return [ ... ];
    },
  })),
};

export default nextConfig;

Then following t3-env docs I have this:

// in next.config.mjs

import { fileURLToPath } from "node:url";
import createJiti from "jiti";
const jiti = createJiti(fileURLToPath(import.meta.url));
 
// Import env here to validate during build. Using jiti we can import .ts files :)
jiti("./app/env");
 

/** @type {import('next').NextConfig} */
const nextConfig = {
  // HOW TO REWRITE HERE ?
  // This file is a mjs file so i cannot import env vars from `app/env.ts`
  ...(process.env.NEXT_PUBLIC_APP_BUILD_MODE === 'static-export' && ({
    output: 'export',
  })),
  ...(process.env.NEXT_PUBLIC_APP_BUILD_MODE === 'api' && ({
    async headers() {
      return [ ... ];
    },
  })),
};

export default nextConfig;

Is this scenario possible ?
Or I need to convert app/env.ts to js ?

[ezeparziale]

You need to convert env.ts to env.mjs for compatibility.

[tresorama]

You need to convert env.ts to env.mjs for compatibility.

Thank you! Will try it!