GAE SDK Path Fixer: detect AppEngine SDK and fix Python sys.path

Overview

Does this look familiar?

>>> from google.appengine.ext import ndb
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named google.appengine.ext

If so, you're probably working with Google App Engine in Python and have some path setup to do!

(One notable case where this happens is attempting to run unit tests for a python GAE project)

You can fix your paths the hard way by copying the ugly runner.py script from the Local Unit Testing for Python tutorial, or you can let gae-sdk-path-fixer take care of it for you in a consistent manner.

Quickstart

First, install gae-sdk-path-fixer (e.g. in a virtualenv):

pip install gae-sdk-path-fixer

Then import the gae_sdk_path_fixer module and call fix_paths() (e.g. in tests/__init__.py):

import gae_sdk_path_fixer
gae_sdk_path_fixer.fix_paths()

Now, if you attempt to run your code and the appengine SDK isn't found, you'll get a helpful error message:

App Engine SDK not found!  Please do one of the following:
- Set $APPENGINE_SDK
- Make sure `dev_appserver.py` on $PATH
- Download the SDK to ./appengine_sdk: `download-gae-sdk [--version 1.9.75] [--dir appengine_sdk]`

Once you've followed the instructions in whatever manner works best for you, rerun the code and import appengine dependencies to your heart's content!

Auto-downloading

If you'd rather make your tools just work without any user intervention, gae-sdk-path-fixer can be instructed to automatically download the SDK if it's not found:

import gae_sdk_path_fixer
gae_sdk_path_fixer.fix_paths(auto_download=True)

Optionally specify a version to download with e.g. version='1.9.75'.

Additional options:

The fix_paths functions takes the following optional arguments:

• auto_download: if True, automatically download App Engine SDK if not found.
• default_dir: default directory to look in; defaults to ./appengine_sdk.
• version: default version; defaults to 1.9.75.