Issue when running Angular app in a Docker container

[blackat]

Hello, I am using

"dependencies": {
    "@angular-devkit/build-angular": "20.3.1",
   "@angular/core": "20.3.0",
   "@ngx-env/builder": "^20.1.1",
}

I have followed the steps in the README so I have created an environment.ts file

export const environment = {
  production: true,
  deploymentColor: import.meta.env.NG_APP_DEPLOYMENT_COLOR,
  deploymentVersion: import.meta.env.NG_APP_DEPLOYMENT_VERSION
};

and the env.d.ts created when I add the @ngx-env

// Define the type of the environment variables.
declare interface Env {
  readonly NODE_ENV: string;
  // Replace the following with your own environment variables.
  // Example: NGX_VERSION: string;
  readonly NG_APP_DEPLOYMENT_COLOR: string;
  readonly NG_APP_DEPLOYMENT_VERSION: string;
}

// Choose how to access the environment variables.
// Remove the unused options.

// 1. Use import.meta.env.YOUR_ENV_VAR in your code. (conventional)
declare interface ImportMeta {
  readonly env: Env;
}

When I deploy via ng serve or a production build locally everything is fine and opening the Chrome dev tools I can see the file <define:_NGX_ENV_> is correctly populated with the env var I have defined via export.

When I pack my app into a Docker container the <define:_NGX_ENV_> file is empty, is there any advice to build the docker image? I have seen the example but I don't want to pass the env var as argument during the build, when I start the container I simply pass -e NG_APP_DEPLOYMENT_COLOR='green' etc.