Establishing a resource:    

The first task which must be completed is creating a connection to your RGW.

import boto3

access='<access>'
secret='<secret>'
endpoint = 'https://<RGW_FQDN>'

s3 = boto3.resource('s3', endpoint_url=endpoint, use_ssl=True, 
        aws_access_key_id=access, aws_secret_access_key=secret)

From here you can reference the 's3' resource to perform actions, such as listing all your buckets:

for bucket in s3.buckets.all():
    print(bucket.name)

Additional s3 examples can be referenced at Boto 3 Docs .