env-vars behaves as build-args by design.

[skrhlm]

What version of Next.js are you using?

10.0.7

What version of Node.js are you using?

14.x

What browser are you using?

Chrome

What operating system are you using?

MacOs

How are you deploying your application?

Kubernetes

Describe the Bug

Simply put the env-vars act as build-args, it is not possible to do any override of env-variables in runtime.

Expected Behavior

Env-vars ( when not using export ) should not be bundled, but updatable through the environment in runtime.

To Reproduce

I've made a repository showcasing the frustration
https://github.com/skrhlm/NEXT-JS-ENV-VARS

[LuudJanssen]

Hi @skrhlm, I think you're looking for Runtime Configuration. This allows you to pass environment variables (through process.env) to runtime configuration. The reason Next.js bundles environment variables during build time by default is explained at the start of the Runtime Configuration documentation:

Generally you'll want to use build-time environment variables to provide your configuration. The reason for this is that runtime configuration adds rendering / initialization overhead and is incompatible with Automatic Static Optimization.

[skrhlm]

Hello @LuudJanssen !

Thanks for your answer. You are right that that using runtime configuration does indeed work. However, I made a new example, this time using getInitialPropsin _app.js to force pages out of automatic static optimization.

This works for all examples, but the one using getStaticProps. Which makes sense since you're unable to opt-out of static optimization when using getStaticProps .

However, the fact still stands that there should be a way to override the default behaviour for getStaticProps. There is still no way to get a site-wide variable through. I understand that this would add some overhead, but a simple bootstrapping process on startup should be able to handle this reasonably efficient.