Next.js Runtime Environment Configuration - Populates your environment at runtime rather than build time.
npm install env-nextjsEffortlessly populate your environment at runtime, not just at build time.
š Highlights:
- Isomorphic Design: Works seamlessly on both server and browser, and even in middleware.
- Next.js 13 & 14 Ready: Fully compatible with the latest Next.js features.
- .env Friendly: Use .env files during development, just like standard Next.js.
In the modern software development landscape, the "[Build once, deploy many][build-once-deploy-many-link]" philosophy is key. This principle, essential for easy deployment and testability, is a [cornerstone of continuous delivery][fundamental-principle-link] and is embraced by the [twelve-factor methodology][twelve-factor-link]. However, front-end development, particularly with Next.js, often lacks support for this - requiring separate builds for different environments. env-nextjs is our solution to bridge this gap in Next.js.
env-nextjs dynamically injects environment variables into your Next.js application at runtime using a script tag loaded before any other script. This approach adheres to the "build once, deploy many" principle, allowing the same build to be used across various environments without rebuilds.
Install with npm install env-nextjs.
In your src/pages/_document.js, replace the Head component with the following:
``js
// src/pages/_document.js
import { Html, Main, NextScript } from "next/document";
import { Head } from "env-nextjs";
export default function Document() {
return (
The
component automatically exposes all environment variables prefixed with NEXT_PUBLIC_ to the browser as window.__NEXT_PUBLIC_ENV__.Add
src/pages/api/_ENV.jsjs
// src/pages/api/_ENV.js
import { createApiRoute } from "env-nextjs/api-route"export default createApiRoute()
`This route is used to bypass Next.js cache & static generation.
$3
Access your environment variables easily:
#### From Components & Pages.
jsx
// src/pages/some-page.jsx
import { env } from 'env-nextjs';export default function SomePage() {
const NEXT_PUBLIC_FOO = env('NEXT_PUBLIC_FOO');
return NEXT_PUBLIC_FOO: {NEXT_PUBLIC_FOO} ;
}
export async function getServerSideProps() {
console.log(
"env from getServerSideProps",
env("NEXT_PUBLIC_BASE_URL")
);
return { props: { } };
}
`#### From Middlewares.
js
// src/middleware.js
import { NextResponse } from 'next/server'
import { env } from 'env-nextjs';export function middleware(request) {
console.log("env inside middleware", env("NEXT_PUBLIC_BASE_URL"));
...
return response
}
`#### From Anywhere.
js
// src/sdk/client.js
import { Client } from 'client'
import { env } from 'env-nextjs';const client = new Client({
host: env("NEXT_PUBLIC_BASE_URL")
})
``Kudos to the next-runtime-env project for the README.
---
[build-once-deploy-many-link]: https://www.mikemcgarr.com/blog/build-once-deploy-many.html
[fundamental-principle-link]: https://cloud.redhat.com/blog/build-once-deploy-anywhere
[twelve-factor-link]: https://12factor.net
[pages-router-branch-link]: https://github.com/expatfile/next-runtime-env/tree/1.x
[next-runtime-env-repo]: https://github.com/expatfile/next-runtime-env