David David - 1 year ago 134
Python Question

unable to call firefox from selenium in python on AWS machine

I am trying to use selenium from python to scrape some dynamics pages with javascript. However, I cannot call firefox after I followed the instruction of selenium on the pypi page(http://pypi.python.org/pypi/selenium). I installed firefox on AWS ubuntu 12.04. The error message I got is:

In [1]: from selenium import webdriver

In [2]: br = webdriver.Firefox()
WebDriverException Traceback (most recent call last)
/home/ubuntu/<ipython-input-2-d6a5d754ea44> in <module>()
----> 1 br = webdriver.Firefox()

/usr/local/lib/python2.7/dist-packages/selenium/webdriver/firefox/webdriver.pyc in __init__(self, firefox_profile, firefox_binary, timeout)
49 RemoteWebDriver.__init__(self,
50 command_executor=ExtensionConnection("", self.profile,
---> 51 self.binary, timeout),
52 desired_capabilities=DesiredCapabilities.FIREFOX)

/usr/local/lib/python2.7/dist-packages/selenium/webdriver/firefox/extension_connection.pyc in __init__(self, host, firefox_profile, firefox_binary, timeout)
45 self.profile.add_extension()
---> 47 self.binary.launch_browser(self.profile)
48 _URL = "http://%s:%d/hub" % (HOST, PORT)
49 RemoteConnection.__init__(

/usr/local/lib/python2.7/dist-packages/selenium/webdriver/firefox/firefox_binary.pyc in launch_browser(self, profile)
43 self._start_from_profile_path(self.profile.path)
---> 44 self._wait_until_connectable()
46 def kill(self):

/usr/local/lib/python2.7/dist-packages/selenium/webdriver/firefox/firefox_binary.pyc in _wait_until_connectable(self)
79 raise WebDriverException("The browser appears to have exited "
80 "before we could connect. The output was: %s" %
---> 81 self._get_firefox_output())
82 if count == 30:
83 self.kill()

WebDriverException: Message: 'The browser appears to have exited before we could connect. The output was: Error: no display specified\n'

I did search on the web and found that this problem happened with other people (https://groups.google.com/forum/?fromgroups=#!topic/selenium-users/21sJrOJULZY). But I don't understand the solution, if it is.

Can anyone help me please? Thanks!

Answer Source

The problem is Firefox requires a display. I've used pyvirtualdisplay in my example to simulate a display. The solution is:

from pyvirtualdisplay import Display
from selenium import webdriver

display = Display(visible=0, size=(1024, 768))

driver= webdriver.Firefox()

<---some code--->

#driver.close() # Close the current window.
driver.quit() # Quit the driver and close every associated window.

Please note that pyvirtualdisplay requires one of the following back-ends: Xvfb, Xephyr, Xvnc.

This should resolve your issue.

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