Improve documetation and provide a working example

[edwardpmorris]

For a new user it is difficult to understand what the eeUtils.init variables are, and what happens when you init.

• suggest make the requirement to link earthengine to the service account clearer
• provide example for the bucket path, and make it clear how this is created and with which settings.
• the various warnings about file_cache is unavailable when using oauth2client >= 4.0.0 or google-auth can confuse users, did it work?

[fgassert]

Thanks Ed -

Would you be interested in helping to clarify/document these things?

• suggest make the requirement to link earthengine to the service account clearer
  It should be possible to auth by doing the following steps if you don't have a service account.

In a notebook

# Authenticate EarthEngine using OAuth2 and your google login. 
!earthengine authenticate --quiet
!earthengine authenticate --authorization-code="{INSERT AUTH CODE HERE}"

# Authenticate gcloud using OAuth2 and your google login
!gcloud auth application-default login

# Credentials are saved to your local environment
eeUtil.init()

If none of the input parameters or environment variables are set, it will run the default ee.Initialize() and storage.Client() which should auth using the default parameters saved to your environment with the command line libraries. Can you see if this works?

• provide example for the bucket path, and make it clear how this is created and with which settings.

The bucket in eeUtil.init() will just be a root bucket e.g. "my-bucket". If it is not specified, the eeUtil will attempt to create a bucket (using the hashed name of your GEE root directory). For functions that take a prefix that would just be a folder path. In the GS URI format these look something like gs://{bucket}/{prefix/to/my/folder}/

• the various warnings about file_cache is unavailable when using oauth2client >= 4.0.0 or google-auth can confuse users, did it work?

I'm not sure what causes this warning, but it seems to happen only if I'm already authenticated and try again. It may be resolved by updating the required library versions but I'd have to investigate. I've created a separate issue #5.