How to conditionally use a development or production environment variable

Question

I'm receiving this error when I start my node application:

ReferenceError: DEV_MAIL_HOST is not defined

The following code works, when I'm specifically defining which env variable to use.

const transport = nodemailer.createTransport({
   host: process.env.DEV_MAIL_HOST,
   port: process.env.DEV_MAIL_PORT,
   auth: {
     user: process.env.DEV_MAIL_USER,
     pass: process.env.DEV_MAIL_PASSWORD
   }
 });

However, I'm trying to conditionally inject env variables based on what mode Node starts up in.

const transport = nodemailer.createTransport({
  host: process.env.NODE_ENV === "development" ? DEV_MAIL_HOST : LIVE_MAIL_HOST,
  port: process.env.NODE_ENV === "development" ? DEV_MAIL_PORT : LIVE_MAIL_PORT,
  auth: {
    user:
      process.env.NODE_ENV === "development" ? DEV_MAIL_USER : LIVE_MAIL_USER,
    pass:
      process.env.NODE_ENV === "development"
        ? DEV_MAIL_PASSWORD
        : LIVE_MAIL_PASSWORD
  }
});

Here's is my package.json, where I define which mode to start in.

 } 
"scripts": {
    "start": "nodemon -e js,graphql -x  NODE_ENV=production node src/index.js",
    "dev": "nodemon -e js,graphql -x NODE_ENV=development node --inspect src/index.js",
 }
}

What am I missing here?

Fixed thanks to @MadWard's comment. I needed to destructure my environment variables.

Answer 1

From both snippets and the error that is shown, you appear to be using variables without declaring them first.

Either use the variables directly by their full name ( process.env.DEV_MAIL_HOST , etc.), or initialize them at the beginning of your code:

const { 
    DEV_MAIL_HOST, 
    DEV_MAIL_PORT, 
    DEV_MAIL_USER,
    DEV_MAIL_PASSWORD,
    LIVE_MAIL_HOST, 
    LIVE_MAIL_PORT, 
    LIVE_MAIL_USER, 
    LIVE_MAIL_PASSWORD
} = process.env;

Answer 2

That's not the correct way to declare environment variables. You should declare an environment variable like: MAIL_HOST

.env file should be different for each environment. In dev .env file MAIL_HOST should contain the development URL and in production .env file MAIL_HOST should contain the production URL

You can choose the env file by using dotenv library by using

require('dotenv').config();