cannot start selenium.WebDriver firefox in java in a box with no UI

Question

I have a something like:

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.firefox.FirefoxDriver;

class Gecko { 


...
FirefoxBinary ffB = new FirefoxBinary();
ffB.setEnvironmentProperty("DISPLAY", ":10");
...
options.setBinary(ffB);
WebDriver driver = new FirefoxDriver(options);

Then I start a virtual frame buffer with:

Xvfb :10 -screen 0 1024x768x24 &

But when I run with Selenium:

java -cp .:selenium-server-standalone-3.5.0.jar Gecko

the following problem shows:

1508364524466 geckodriver::marionette INFO Starting browser /usr/bin/firefox with args ["-marionette"]
Error: GDK_BACKEND does not match available displays
Exception in thread "main" org.openqa.selenium.WebDriverException: connection refused

Which could be a possible cause? User permission? Firewall? The current box doesn't have any desktop environment installed.

Answer 1

If it says Error: GDK_BACKEND does not match available displays then install pyvirtualdisplay:

pip install pyvirtualdisplay selenium
You might need xvfb too:

sudo apt-get install xvfb
Then try adding this code:

from pyvirtualdisplay import Display
display = Display(visible=0, size=(800, 600))
display.start()
Full example:

from pyvirtualdisplay import Display
from selenium import webdriver

display = Display(visible=0, size=(800, 600))
display.start()

browser = webdriver.Firefox()
browser.get('http://www.python.org')

browser.close()
display.stop()