node-backend-example/src/db.js

// Importing the Knex library
import knex from 'knex';
import 'dotenv/config'

if (!process.env.DB_URL) {
  fail("Ensure you set DB_URL");
};

// Creating an instance of Knex
export default knex({
    client: 'postgres',
    connection: process.env.DB_URL
});