We are receiving an error:

ImportError: No module named OAuth2Client

We have noticed scores of questions around this topic, many unanswered and at least one answer that describes the solution of copying over files from the Google App Engine SDK.

This approach, however, seems tedious because all the dependencies are unclear. If we copy over oauth2client then run, the next error is another module that is missing. Fix that, then another module is missing, etc., etc.

What is ironic is that we can see all the files and modules needed, listed from Google App Engine SDK right in PyCharm but they seem inaccessible to the script.

Is there no better way to pull in all the files that oauth2client needs for Python to work on App Engine?

The answer is to "vendor" in the file(s).

We found a quick way to solve this based on this documentation https://cloud.google.com/appengine/docs/python/tools/libraries27#vendoring and this SO answer.

1. Create a new folder called "lib" in the same folder as your app.yaml file. (You can name it something else. Just use that name below.)

2. Create an empty file called appengine_config.py in the same folder as your app.yaml file

3. Add two lines to that appengine_config.py file:

   from google.appengine.ext import vendor vendor.add('lib')

4. From terminal, navigate to the directory which contains that file and execute the following command:

   sudo pip install -t lib google-api-python-client

The import error will disappear and you will have all the sub-dependent modules as well.