How to Run Selenium Tests on Headless Servers without Encountering 'Error: cannot open display: :0'?

Running Selenium in Xvfb: Troubleshooting Display Errors on Headless Servers

Problem:

When running Selenium tests on an Amazon EC2 instance without a graphical user interface (GUI), users may encounter the error:

Error: cannot open display: :0

despite installing necessary packages like Selenium, Firefox, and Xvfb.

Solution:

To run Selenium without a visible display, PyVirtualDisplay or Xvfbwrapper provide headless solutions.

PyVirtualDisplay

from pyvirtualdisplay import Display
from selenium import webdriver

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

# now Firefox will run in a virtual display. 
# you will not see the browser.
browser = webdriver.Firefox()
browser.get('http://www.google.com')
print browser.title
browser.quit()

display.stop()

Xvfbwrapper

from xvfbwrapper import Xvfb

vdisplay = Xvfb()
vdisplay.start()

# launch stuff inside virtual display here

vdisplay.stop()

Alternatively, for cleaner context management, use Xvfbwrapper as follows:

from xvfbwrapper import Xvfb

with Xvfb() as xvfb:
    # launch stuff inside virtual display here.
    # It starts/stops in this code block.

By using these headless solutions, Selenium tests can run successfully on servers without GUI capabilities, enabling automation and testing in headless environments.

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