I have a Angular + Spring boot application that is deployed on Heroku. To setup environment variables at Spring for Heroku to patch, I just have to declare spring.datasource.username= inside the application-prod.properties and fill up the information at Heroku Config Vars. Question : How should I do this for the Angular's environment variable inside the environment-prod.ts so that the Heroku can patch the value into it during deployment? An example would be great. Thanks.

How to setup Angular environment variables for Heroku to patch during deployment?

I have a Angular + Spring boot application that is deployed on Heroku.

To setup environment variables at Spring for Heroku to patch, I just have to declare spring.datasource.username= inside the application-prod.properties and fill up the information at Heroku Config Vars.
Question : How should I do this for the Angular's environment variable inside the environment-prod.ts so that the Heroku can patch the value into it during deployment? An example would be great.

Thanks.