I mentioned already how to set up Eclipse to get code completion for the Google App Engine development environment. To run the application from inside Eclipse has some advantages, too: All errors are logged to the console and you can directly jump to the error location in the code.

The run configuration needs to use the following main module:

/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/dev_appserver.py