Use OS environment variable to get configuration on Angular

set-env.ts

// This script is based from https://medium.com/@natchiketa/angular-cli-and-os-environment-variables-4cfa3b849659
import { writeFile } from 'fs';
import { argv } from 'yargs';

const environment = argv.environment;
const isProd = environment === 'prod';

require('dotenv').config({path: `./set-env/.env.${environment}`});

const targetPath = `./src/environments/environment.${environment}.ts`;

const envConfigFile = `
export const environment = {
  production: ${isProd}
};
`;

writeFile(targetPath, envConfigFile, function (err) {
  if (err) {
    console.log(err);
  }

  console.log(`Output generated at ${targetPath}`);
});