If you want to interact with google cloud storage services outside of the App Engine environment, you may use Gcloud (https://googlecloudplatform.github.io/gcloud-python/stable/) to do so.
You need a service account on your application as well as download the JSON credentials file. With those, once you install the proper packages, you'll be able to make queries as well as write data.
Here is an example of authenticating yourself to use the library:
from gcloud import datastore
# the location of the JSON file on your local machine
os.environ["GOOGLE_APPLICATION_CREDENTIALS"] = "/location/client_secret.json"
# project ID from the Developers Console
projectID = "THE_ID_OF_YOUR_PROJECT"
os.environ["GCLOUD_TESTS_PROJECT_ID"] = projectID
os.environ["GCLOUD_TESTS_DATASET_ID"] = projectID
client = datastore.Client(dataset_id=projectID)
Edit:
This library is for the following as per the docs here(https://github.com/GoogleCloudPlatform/gcloud-python):
This client supports the following Google Cloud Platform services:
Google Cloud Datastore
Google Cloud Storage
Google Cloud Pub/Sub
Google BigQuery
Google Cloud Resource Manager