Locust Web界面访问报错AttributeError: 'Request'对象无'is_xhr'属性

问题表现 #

本地启动Locust服务后，访问Web管理界面地址localhost:8089时页面无法正常加载，服务端抛出属性不存在异常，无正常业务日志输出。

错误根因 #

该报错由依赖包版本不兼容导致：Werkzeug 1.0.0及以上版本正式移除了早已废弃的is_xhr请求属性，但低版本Locust依赖的Flask框架仍在接口返回的JSON格式化逻辑中调用该属性，触发属性不存在异常。

完整报错栈 #

Traceback (most recent call last):
  File "/Users/kuldeep.yadav/Documents/locustTutorial/venv/lib/python3.9/site-packages/gevent/pywsgi.py", line 999, in handle_one_response
    self.run_application()
  File "/Users/kuldeep.yadav/Documents/locustTutorial/venv/lib/python3.9/site-packages/gevent/pywsgi.py", line 945, in run_application
    self.result = self.application(self.environ, self.start_response)
  File "/Users/kuldeep.yadav/Documents/locustTutorial/venv/lib/python3.9/site-packages/flask/app.py", line 1997, in __call__
    return self.wsgi_app(environ, start_response)
  File "/Users/kuldeep.yadav/Documents/locustTutorial/venv/lib/python3.9/site-packages/flask/app.py", line 1985, in wsgi_app
    response = self.handle_exception(e)
  File "/Users/kuldeep.yadav/Documents/locustTutorial/venv/lib/python3.9/site-packages/flask/app.py", line 1540, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/Users/kuldeep.yadav/Documents/locustTutorial/venv/lib/python3.9/site-packages/flask/_compat.py", line 33, in reraise
    raise value
  File "/Users/kuldeep.yadav/Documents/locustTutorial/venv/lib/python3.9/site-packages/flask/app.py", line 1982, in wsgi_app
    response = self.full_dispatch_request()
  File "/Users/kuldeep.yadav/Documents/locustTutorial/venv/lib/python3.9/site-packages/flask/app.py", line 1614, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/Users/kuldeep.yadav/Documents/locustTutorial/venv/lib/python3.9/site-packages/flask/app.py", line 1517, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/Users/kuldeep.yadav/Documents/locustTutorial/venv/lib/python3.9/site-packages/flask/_compat.py", line 33, in reraise
    raise value
  File "/Users/kuldeep.yadav/Documents/locustTutorial/venv/lib/python3.9/site-packages/flask/app.py", line 1612, in full_dispatch_request
    rv = self.dispatch_request()
  File "/Users/kuldeep.yadav/Documents/locustTutorial/venv/lib/python3.9/site-packages/flask/app.py", line 1598, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/Users/kuldeep.yadav/Documents/locustTutorial/venv/lib/python3.9/site-packages/locust/web.py", line 366, in wrapper
    return view_func(*args, **kwargs)
  File "/Users/kuldeep.yadav/Documents/locustTutorial/venv/lib/python3.9/site-packages/locust/util/cache.py", line 22, in wrapper
    cache["result"] = func(*args, **kwargs)
  File "/Users/kuldeep.yadav/Documents/locustTutorial/venv/lib/python3.9/site-packages/locust/web.py", line 301, in request_stats
    return jsonify(report)
  File "/Users/kuldeep.yadav/Documents/locustTutorial/venv/lib/python3.9/site-packages/flask/json.py", line 251, in jsonify
    if current_app.config['JSONIFY_PRETTYPRINT_REGULAR'] and not request.is_xhr:
  File "/Users/kuldeep.yadav/Documents/locustTutorial/venv/lib/python3.9/site-packages/werkzeug/local.py", line 347, in __getattr__
    return getattr(self._get_current_object(), name)
AttributeError: 'Request' object has no attribute 'is_xhr'
2021-10-22T15:58:55Z {'REMOTE_ADDR': '::ffff:127.0.0.1', 'REMOTE_PORT': '50803', 'HTTP_HOST': 'localhost:8089', (hidden keys: 28)} failed with AttributeError

解决方案 #

• 方案一（推荐）：升级Locust到2.0及以上正式版本，新版已官方修复该兼容性问题，执行命令pip install -U locust即可完成升级
• 方案二：如果需要保留当前Locust版本，可降级Werkzeug到兼容版本，执行命令pip install werkzeug==0.16.1，该版本仍保留is_xhr属性，可正常适配旧版Locust
• 方案三（临时修改）：找到依赖包目录下的flask/json.py文件，将251行的判断逻辑if current_app.config['JSONIFY_PRETTYPRINT_REGULAR'] and not request.is_xhr:修改为if current_app.config['JSONIFY_PRETTYPRINT_REGULAR'] and not request.headers.get('X-Requested-With') == 'XMLHttpRequest':，替换is_xhr的原有实现逻辑即可解决问题

内容的提问来源于stack exchange，提问作者Kuldeep Yadav