Use dotenv-expand instead of dotenv

[AnandChowdhary]

I'm submitting feature request

We should use dotenv-expand instead of dotenv.

Instead of this:

import { config } from 'dotenv';
config();

We should do this:

import { config } from 'dotenv';
import dotenvExpand from 'dotenv-expand';
dotenvExpand(config());

Current behavior

We use dotenv to fetch configuration from the .env file

Expected behavior

We should switch to using dotenv-expand

What is the motivation / use case for changing the behavior?

Using dotenv-expand, we can do this:

DB_PROVIDER = "my-database-provider"
DB_USER = "my-database-user"
DB_PASSWORD = "my-database-password"
DB_HOST = "my-database-host"
DB_POST = 3306
DB_NAME = "my-database-name"
DATABASE_URL = "${DB_PROVIDER}://${DB_USER}:${DB_PASSWORD}@${DB_HOST}:${DB_POST}/${DB_NAME}"

Currently, we'd have to specify the full DATABASE_URL.

[kamilmysliwiec]

https://docs.nestjs.com/techniques/configuration#expandable-variables

[AnandChowdhary]

Oops, thanks!