env-loader.ts

import dotenv from "dotenv";
import { readFileSync } from "fs";

const compareKeys = (sample: object, config: object) => {
  const configKeys = Object.keys(config);
  return Object.keys(sample).every(key => configKeys.includes(key));
};

const loadEnv = () => {
  const buffer = readFileSync(".env.example");
  const sample = dotenv.parse(buffer);
  const config = dotenv.config();
  const match = compareKeys(sample, config.parsed || {});
  if (!match) {
    // tslint:disable-next-line: no-console
    console.error("Failed to load .env, .env.example and .env differs.");
    process.exit(1);
  }
  return config;
};