树莓派root用户运行Selenium+Chromium脚本白屏及元素找不到异常

问题说明 #

预期脚本行为：全屏打开Chromium浏览器并自动完成网站登录。
异常表现：pi用户运行正常，root用户运行时先显示data;空白页，随后跳转至隐私错误页，最终抛出找不到页面元素的异常。

测试代码 #

#!/home/pi/Documents/raspberry_screen_chrome_script/selenium/bin/python3
from selenium import webdriver
from selenium.webdriver.chrome.options import Options
from webdriver_manager.chrome import ChromeDriverManager

username_django = 'username'
password_django = 'password'

chrome_options = Options()

chrome_options.add_argument('--no-sandbox')
chrome_options.add_argument("--remote-debugging-port=9222");
chrome_options.add_experimental_option("useAutomationExtension", False)
chrome_options.add_experimental_option("excludeSwitches", ["enable-automation"])
chrome_options.add_argument("--start-fullscreen")
chrome_options.add_argument("--kiosk")

driver = webdriver.Chrome('/usr/lib/chromium-browser/chromedriver', options=chrome_options)
driver.get ("my_url")
driver.find_element_by_id('id_username').send_keys(username_django)
driver.find_element_by_id('password-input').send_keys(password_django)
driver.find_element_by_id('submit-login').click()

环境依赖版本 #

selenium==3.141.0
webdriver-manager==3.4.2
Chromium 88.0.4324.187 Built on Raspbian , running on Raspbian 10
ChromeDriver 88.0.4324.187

异常堆栈信息 #

root@raspberrypi:/home/pi/Documents/raspberry_screen_chrome_script# ./interface_login_local.py 
Traceback (most recent call last):
  File "./interface_login_local.py", line 21, in <module>
    driver.find_element_by_id('id_username').send_keys(username_django)
  File "/home/pi/Documents/raspberry_screen_chrome_script/selenium/lib/python3.7/site-packages/selenium/webdriver/remote/webdriver.py", line 360, in find_element_by_id
    return self.find_element(by=By.ID, value=id_)
  File "/home/pi/Documents/raspberry_screen_chrome_script/selenium/lib/python3.7/site-packages/selenium/webdriver/remote/webdriver.py", line 978, in find_element
    'value': value})['value']
  File "/home/pi/Documents/raspberry_screen_chrome_script/selenium/lib/python3.7/site-packages/selenium/webdriver/remote/webdriver.py", line 321, in execute
    self.error_handler.check_response(response)
  File "/home/pi/Documents/raspberry_screen_chrome_script/selenium/lib/python3.7/site-packages/selenium/webdriver/remote/errorhandler.py", line 242, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.NoSuchElementException: Message: no such element: Unable to locate element: {"method":"css selector","selector":"[id=\"id_username\"]"}
  (Session info: chrome=88.0.4324.187)

运行行为对比 #

• pi用户运行表现：
• root用户运行表现（右键点击时会出现白色块）：

问题原因 #

root用户和pi用户的证书信任存储相互独立，你访问的目标站点使用了自签名/私有CA签发的HTTPS证书，pi用户已经信任该证书，root用户未信任，导致Chromium跳转到隐私错误页，页面没有渲染登录表单，自然找不到对应元素。

解决方案 #

方案一：添加启动参数跳过证书校验 #

在chrome_options配置段新增以下两行参数，直接忽略HTTPS证书错误：

chrome_options.add_argument('--ignore-certificate-errors')
chrome_options.add_argument('--allow-running-insecure-content')

方案二：全局导入信任证书 #

如果需要保留证书校验逻辑，可将目标站点的证书导入系统全局信任存储：

1. 将证书文件（.crt后缀）放入/usr/local/share/ca-certificates/目录
2. 执行命令update-ca-certificates生效，所有用户都会信任该证书

可选优化：添加页面加载等待逻辑 #

避免网络波动导致页面未加载完成就查找元素报错，可添加显式等待：

from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
from selenium.webdriver.common.by import By

# 最多等待10秒，直到目标元素加载完成
WebDriverWait(driver, 10).until(EC.presence_of_element_located((By.ID, 'id_username')))
driver.find_element_by_id('id_username').send_keys(username_django)

内容的提问来源于stack exchange，提问作者Welyweloo