Variables saved in the .env file of a project directory will be added to the environment when run by foreman.

For example, we can set SRCPATH_ENV to development in your environment, as shown in the following screenshot:

The command in the preceding screenshot runs the interactive shell and sets the value of the SRCPATH_ENV environment variable to SMS.

You can use the .env file for the local configuration as it has settings specific to your local environment. It does not need to be checked in or committed to Heroku.