How to run NPM run script passing env variable (calling the appropriate env.{env} file)?

Question

I'm on NodeJs app, I've create two files:

.env
.env.production

on the first I have dev settings, on the later prod settings.

Now, running on local, I'd like to do this:

npm run jobs_orders

Configured this way within package.json:

"scripts": {
    "job_orders": "supervisor --mode production jobs/job_orders.js",
},

But later on app, when doing:

import 'dotenv/config';
...
process.env.DATABASE_CONNECTION_STRING

it always read the DATABASE_CONNECTION_STRING settings on .env file, not the one on env.production.

Where am I wrong? And how do I fix it?

Answer 1

Because dotenv will load the environment variables located in path.resolve(process.cwd(), '.env') by default.

You can set the process.env.NODE_ENV variable to determine which .env to load for different environments.

index.mjs:

import { config } from 'dotenv';
import path from 'path';

const nodeEnv = process.env.NODE_ENV || '';

config({ path: path.resolve(process.cwd(), `.env${nodeEnv ? '.' + nodeEnv : ''}`) });

console.log('process.env.DATABASE_CONNECTION_STRING: ', process.env.DATABASE_CONNECTION_STRING);

.env

DATABASE_CONNECTION_STRING=dev

.env.production

DATABASE_CONNECTION_STRING=prd

Development:

$ node index.mjs 
process.env.DATABASE_CONNECTION_STRING:  dev

Production:

$ NODE_ENV=production node index.mjs 
process.env.DATABASE_CONNECTION_STRING:  prd

Reference:

• react-scripts/config/env.js

• What other .env files can be used?

Node version: v14.21.3