API url environment not used when running with docker production stage

[bobvandevijver]

Consider the following snippet from docker compose, where the 'gui' folder contains a clone of this repository.

  hawkbit-gui:
    build:
      context: ./gui
      target: production-build-stage
      dockerfile: Dockerfile
    environment:
      - NEXTAUTH_SECRET=<some-secret>
      - NEXTAUTH_URL=https://<some-hawkbitgui-url>
      - NEXT_PUBLIC_HAWKBIT_API_URL=https://<some-hawkbit-url>

This will, when run, result in the following error being logged when trying to login:

Attaching to hawkbit-gui-1                                                                                                                        
hawkbit-gui-1  | $ next start                                                                                                                     
hawkbit-gui-1  |    ▲ Next.js 16.0.10                                                                                                             
hawkbit-gui-1  |    - Local:         http://localhost:3000                                                                                        
hawkbit-gui-1  |    - Network:       http://172.24.0.4:3000                                                                                       
hawkbit-gui-1  |                                                                                                                                  
hawkbit-gui-1  |  ✓ Starting...                                                                                                                   
hawkbit-gui-1  | [baseline-browser-mapping] The data in this module is over two months old.  To ensure accurate Baseline data, please update: `npm i baseline-browser-mapping@latest -D`
hawkbit-gui-1  |  ✓ Ready in 649ms
hawkbit-gui-1  | TypeError: Invalid URL
hawkbit-gui-1  |     at t (.next/server/chunks/_06c8e80d._.js:3:4782)
hawkbit-gui-1  |     at <unknown> (.next/server/chunks/_06c8e80d._.js:3:12885)
hawkbit-gui-1  |     at new Promise (<anonymous>)
hawkbit-gui-1  |     at http (.next/server/chunks/_06c8e80d._.js:3:12805)
hawkbit-gui-1  |     at tU.tF (.next/server/chunks/_06c8e80d._.js:3:22901)
hawkbit-gui-1  |     at tU._request (.next/server/chunks/_06c8e80d._.js:3:25921)
hawkbit-gui-1  |     at tU.request (.next/server/chunks/_06c8e80d._.js:3:24280)
hawkbit-gui-1  |     at tU.<computed> [as get] (.next/server/chunks/_06c8e80d._.js:3:26235)
hawkbit-gui-1  |     at Function.get (.next/server/chunks/_06c8e80d._.js:1:62984)
hawkbit-gui-1  |     at tU.request (.next/server/chunks/_06c8e80d._.js:3:24365) {
hawkbit-gui-1  |   code: 'ERR_INVALID_URL',
hawkbit-gui-1  |   input: '/rest/v1/userinfo'
hawkbit-gui-1  | }

It looks like the environment variable has been replaced during the bun run build, and no longer uses the env that is actually set. I have validated that the environment values are available when opening a bash instance inside the running container.

When passing the environment as 'args' during the container build (as below), it does work as expected.

  hawkbit-gui:
    build:
      context: ./gui
      target: production-build-stage
      dockerfile: Dockerfile
      args:
        - NEXTAUTH_SECRET=<some-secret>
        - NEXTAUTH_URL=https://<some-hawkbitgui-url>
        - NEXT_PUBLIC_HAWKBIT_API_URL=https://<some-hawkbit-url>
    environment:

[eHeinrich-wsa]

I ran into this issue as well.

The Problem is that environment variables starting with NEXT_PUBLIC_ are magic variables in next.js. They are hardcoded into the bundle at built time. I think the variable is not used client side, so i would suggest renaming NEXT_PUBLIC_HAWKBIT_API_URL. If it is actually required in the client, I would suggest to pass the args by default like in the example above.

[bobvandevijver]

This makes total sense, and also explains why keeping the NEXTAUTH_ ones as env do work. Renaming the environment should indeed solve the issue then.