Unix: Loading env variables, without messing up your environment

If you're developing a server or a web app, and this server needs to interact with third-party services, you're probably going to use a .env (dotenv) file to define those variables. At least, when running your project locally.

So, you would probably end up doing something like export $(cat .env | xargs), and then running your process.

This approach has one major drawback: it updates the environment of your current shell, and it has a few implications:

• If you're working with several services, with various dotenv files, you may end up overwriting variables, or relying on variables defined by other services...
• ...worst-case scenario, you end up connecting to a production database when running a task that was supposed to run against a test database, and things go wild.
• You may leak tokens every time you call env in your terminal. Not ideal if you're streaming your content.

You can actually make sure your application loads its necessary environment variables without those inconveniences, either by using a Shell script, or a Makefile. Two very simple solutions compared to, say, setting up and maintaining SOPS1.

So, basically by adding something like server.sh with the following:

#!/bin/sh
export $(cat .env | xargs)
# Running your server

Your env will be loaded inside the context of a new TTY (if I remember my UNIX lessons correctly).

It also works with Makefiles (and yeah, I hate the syntax, it's annoying and weird, but I always end up writing Makefiles):

include .env
export

server:
  # Running your server

And that's it. Also, make sure your variables are properly defined (such as FOO=bar, without quotes) because having additional quotes may cause issues (some loaders would escape quotes).

Not a revolutionary take, but better be safe (and clean) than sorry!