python - from cryptography.hazmat.bindings._constant_time import lib ImportError: No module named _constant_time

Question

I am basically deploying a flask app in app engine that uses pywebpush(https://github.com/web-push-libs/pywebpush). I followed the following tutorial to deploy(https://cloud.google.com/appengine/docs/standard/python/getting-started/python-standard-env) But i am constantly getting the error in app engine while it works fine in local system. The Error is: "from cryptography.hazmat.bindings._constant_time import lib ImportError: No module named _constant_time". Can Someone help me to over come this?

Answer 1

That library is not included in App Engine, so, you have to include it.

Follow the commands in Copying a third-party library, in your case, with pywebpush, to do so.

EDIT: pywebpush depends on a library with C extensions, which can not be used in Standard. To be able to use pywebpush, you will have to move to App Engine Flexible. I have followed this example, adding the pywebpush dependency and calling a function from it, and it worked both in local and deployed.