Pick the Browser, Headless Mode and Grid From Environment Variables

public static WebDriver createDriver() throws MalformedURLException {
  String browser = System.getenv().getOrDefault("BROWSER", "chrome");
  boolean headless = !"false".equalsIgnoreCase(System.getenv().getOrDefault("HEADLESS", "true"));
  String grid = System.getenv("GRID_URL");

  AbstractDriverOptions<?> options = switch (browser) {
      case "firefox" -> { FirefoxOptions o = new FirefoxOptions(); if (headless) o.addArguments("-headless"); yield o; }
      case "edge"    -> { EdgeOptions o = new EdgeOptions(); if (headless) o.addArguments("--headless=new"); yield o; }
      default        -> { ChromeOptions o = new ChromeOptions(); if (headless) o.addArguments("--headless=new"); o.addArguments("--window-size=1366,768"); yield o; }
  };

  if (grid != null && !grid.isBlank()) return new RemoteWebDriver(new URL(grid), options);
  return switch (browser) {
      case "firefox" -> new FirefoxDriver((FirefoxOptions) options);
      case "edge"    -> new EdgeDriver((EdgeOptions) options);
      default        -> new ChromeDriver((ChromeOptions) options);
  };
}

// BROWSER=firefox HEADLESS=false mvn test
// GRID_URL=http://grid:4444 mvn test

import os
from selenium import webdriver

def create_driver():
  browser = os.getenv("BROWSER", "chrome")
  headless = os.getenv("HEADLESS", "true").lower() != "false"
  grid = os.getenv("GRID_URL")

  if browser == "firefox":
      options = webdriver.FirefoxOptions()
      if headless: options.add_argument("-headless")
  elif browser == "edge":
      options = webdriver.EdgeOptions()
      if headless: options.add_argument("--headless=new")
  else:
      options = webdriver.ChromeOptions()
      if headless: options.add_argument("--headless=new")
      options.add_argument("--window-size=1366,768")

  if grid:
      return webdriver.Remote(command_executor=grid, options=options)
  return {"firefox": webdriver.Firefox, "edge": webdriver.Edge}.get(browser, webdriver.Chrome)(options=options)

# BROWSER=firefox HEADLESS=false pytest
# GRID_URL=http://grid:4444 pytest

const { Builder } = require('selenium-webdriver');
const chrome = require('selenium-webdriver/chrome');
const firefox = require('selenium-webdriver/firefox');
const edge = require('selenium-webdriver/edge');

async function createDriver() {
const browser = process.env.BROWSER ?? 'chrome';
const headless = (process.env.HEADLESS ?? 'true') !== 'false';
const grid = process.env.GRID_URL;

const chromeOpts = new chrome.Options().addArguments('--window-size=1366,768');
const firefoxOpts = new firefox.Options();
const edgeOpts = new edge.Options();
if (headless) {
  chromeOpts.addArguments('--headless=new');
  firefoxOpts.addArguments('-headless');
  edgeOpts.addArguments('--headless=new');
}

const builder = new Builder().forBrowser(browser)
  .setChromeOptions(chromeOpts).setFirefoxOptions(firefoxOpts).setEdgeOptions(edgeOpts);
if (grid) builder.usingServer(grid);
return builder.build();
}

// BROWSER=firefox HEADLESS=false npm test
// GRID_URL=http://grid:4444 npm test

public static IWebDriver CreateDriver()
{
  var browser = Environment.GetEnvironmentVariable("BROWSER") ?? "chrome";
  var headless = !string.Equals(Environment.GetEnvironmentVariable("HEADLESS") ?? "true", "false", StringComparison.OrdinalIgnoreCase);
  var grid = Environment.GetEnvironmentVariable("GRID_URL");

  DriverOptions options;
  switch (browser)
  {
      case "firefox": { var o = new FirefoxOptions(); if (headless) o.AddArgument("-headless"); options = o; break; }
      case "edge":    { var o = new EdgeOptions(); if (headless) o.AddArgument("--headless=new"); options = o; break; }
      default:        { var o = new ChromeOptions(); if (headless) o.AddArgument("--headless=new"); o.AddArgument("--window-size=1366,768"); options = o; break; }
  }

  if (!string.IsNullOrWhiteSpace(grid)) return new RemoteWebDriver(new Uri(grid), options);
  return browser switch
  {
      "firefox" => new FirefoxDriver((FirefoxOptions)options),
      "edge" => new EdgeDriver((EdgeOptions)options),
      _ => new ChromeDriver((ChromeOptions)options),
  };
}

// $env:BROWSER="firefox"; $env:HEADLESS="false"; dotnet test