Runtime Config

Warning:

This feature is deprecated. We recommend using environment variables instead, which also can support reading runtime values.

You can run code on server startup using the register function.

This feature does not work with Automatic Static Optimization, Output File Tracing, or React Server Components.

To add runtime configuration to your app, open next.config.js and add the publicRuntimeConfig and serverRuntimeConfig configs:

next.config.js

module.exports = {
  serverRuntimeConfig: {
    // Will only be available on the server side
    mySecret: 'secret',
    secondSecret: process.env.SECOND_SECRET, // Pass through env variables
  },
  publicRuntimeConfig: {
    // Will be available on both server and client
    staticFolder: '/static',
  },
}

Place any server-only runtime config under serverRuntimeConfig.

Anything accessible to both client and server-side code should be under publicRuntimeConfig.

A page that relies on publicRuntimeConfig must use getInitialProps or getServerSideProps or your application must have a Custom App with getInitialProps to opt-out of Automatic Static Optimization. Runtime configuration won't be available to any page (or component in a page) without being server-side rendered.

To get access to the runtime configs in your app use next/config, like so:

import getConfig from 'next/config'
import Image from 'next/image'
 
// Only holds serverRuntimeConfig and publicRuntimeConfig
const { serverRuntimeConfig, publicRuntimeConfig } = getConfig()
// Will only be available on the server-side
console.log(serverRuntimeConfig.mySecret)
// Will be available on both server-side and client-side
console.log(publicRuntimeConfig.staticFolder)
 
function MyImage() {
  return (
    <div>
      <Image
        src={`${publicRuntimeConfig.staticFolder}/logo.png`}
        alt="logo"
        layout="fill"
      />
    </div>
  )
}
 
export default MyImage