selenium 3.6.0 geckodriver的一次坑

Traceback (most recent call last):
  File "./se3.py", line 16, in <module>
    dr=webdriver.Firefox(firefox_binary=binary,executable_path=driver_path)
  File "/opt/python36/lib/python3.6/site-packages/selenium/webdriver/firefox/webdriver.py", line 154, in __init__
    keep_alive=True)
  File "/opt/python36/lib/python3.6/site-packages/selenium/webdriver/remote/webdriver.py", line 151, in __init__
    self.start_session(desired_capabilities, browser_profile)
  File "/opt/python36/lib/python3.6/site-packages/selenium/webdriver/remote/webdriver.py", line 240, in start_session
    response = self.execute(Command.NEW_SESSION, parameters)
  File "/opt/python36/lib/python3.6/site-packages/selenium/webdriver/remote/webdriver.py", line 308, in execute
    self.error_handler.check_response(response)
  File "/opt/python36/lib/python3.6/site-packages/selenium/webdriver/remote/errorhandler.py", line 194, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.WebDriverException: Message: failed to lookup address information: Name does not resolve

一开始以为是geckodriver的问题，于是在不同的geckodriver换来换去，firefox也试过不同的版本，然而并没有解决。百度了一下也没有相关的问题。

最后还是看错误信息，failed to lookup address information: Name does not resolve，

启动geckodriver的时候1508740937900    geckodriver    INFO    Listening on 127.0.0.1:4444

想到会不会是/etc/hosts的问题，于是在/etc/hosts上添加

127.0.0.1   localhost

问题解决。