RuntimeError: Working outside of application context

[jossefaz]

We have a Flask Application that sending HTTP requests to an external service (ArangoDB for instance)

From a simple route that send an HTTP Request to our DB server :

@app.route('/get_all_data', methods=['POST'])
def get_all_data():
    data = arango_db.aql.execute(query)
    return jsonify(data)

Sometimes we receiving this Traceback:

Traceback (most recent call last):

File "/usr/local/lib/python3.7/dist-packages/flask/app.py", line 2077, in wsgi_app
response = self.full_dispatch_request()

File "/usr/local/lib/python3.7/dist-packages/flask/app.py", line 1525, in full_dispatch_request
rv = self.handle_user_exception(e)

File "/usr/local/lib/python3.7/dist-packages/flask/app.py", line 1523, in full_dispatch_request
rv = self.dispatch_request()

File "/usr/local/lib/python3.7/dist-packages/flask/app.py", line 1509, in dispatch_request
return self.ensure_sync(self.view_functions[rule.endpoint])(**req.view_args)

File "./routes/data.py", line 67, in get_all_data
return jsonify(results)

File "/usr/local/lib/python3.7/dist-packages/flask/json/__init__.py", line 289, in jsonify
if current_app.config["JSONIFY_PRETTYPRINT_REGULAR"] or current_app.debug:

File "/usr/local/lib/python3.7/dist-packages/werkzeug/local.py", line 278, in __get__
obj = instance._get_current_object()

File "/usr/local/lib/python3.7/dist-packages/werkzeug/local.py", line 407, in _get_current_object
return self.__local() # type: ignore

File "/usr/local/lib/python3.7/dist-packages/flask/globals.py", line 47, in _find_app
raise RuntimeError(_app_ctx_err_msg)

RuntimeError: Working outside of application context.
This typically means that you attempted to use functionality that needed
to interface with the current application object in some way. To solve
this, set up an application context with app.app_context(). See the
documentation for more information.

I was wondering what could be the issue : how Flask would loose the request context ?

Here are the version we use :

Flask==2.1.2
Werkzeug==2.1.2

We call this function only through HTTP request (no direct call to this function)
Does this werkzug PR (pallets/werkzeug@9741ea9) could solve our issue ? Can you explain a bit more on this refactoring ?

This query to the DB server is currently returning a very large amount of data and could take some time....and even sometime, the DB server is disconnecting. But even if this occurs, I cannot face out why and if this would lead Flask app to lost the request context...