To authenticate against a Compute endpoint, instantiate a novaclient.v_1_1.client.Client object: from os import environ as env import novaclient.v1_1.client as nvclient nova = nvclient.Client(auth_url=env['OS_AUTH_URL'], username=env['OS_USERNAME'], api_key=env['OS_PASSWORD'], project_id=env['OS_TENANT_NAME'], region_name=env['OS_REGION_NAME']) Alternatively, you can instantiate a novaclient.client.Client object and pass the version number: from os import environ as env import novaclient nova = novaclient.client.Client("1.1", auth_url=env['OS_AUTH_URL'], username=env['OS_USERNAME'], api_key=env['OS_PASSWORD'], project_id=env['OS_TENANT_NAME'], region_name=env['OS_REGION_NAME']) If you authenticate against an endpoint that uses a custom authentication back-end, you must load the authentication plug-in and pass it to the constructor. The Rackspace public cloud is an OpenStack deployment that uses a custom authentication back end. To authenticate against this cloud, you must install the rackspace-novaclient library that contains the Rackspace authentication plug-in, called rackspace. The following Python code shows the additional modifications required to instantiate a Client object that can authenticate against the Rackspace custom authentication back end. import novaclient.auth_plugin import novaclient.v1_1.client as nvclient from os import environ as env auth_system = 'rackspace' auth_plugin = novaclient.auth_plugin.load_plugin('rackspace') nova = nvclient.Client(auth_url=env['OS_AUTH_URL'], username=env['OS_USERNAME'], api_key=env['OS_PASSWORD'], project_id=env['OS_TENANT_NAME'], region_name=env['OS_REGION_NAME'], auth_system='rackspace', auth_plugin=auth_plugin) If you set the OS_AUTH_SYSTEM environment variable, check for this variable in your Python script to determine whether you need to load a custom authentication back end: import novaclient.auth_plugin import novaclient.v1_1.client as nvclient from os import environ as env auth_system = os.get('OS_AUTH_SYSTEM') if auth_system and auth_system != "keystone": auth_plugin = novaclient.auth_plugin.load_plugin(auth_system) else: auth_plugin = None nova = nvclient.Client(auth_url=env['OS_AUTH_URL'], username=env['OS_USERNAME'], api_key=env['OS_PASSWORD'], project_id=env['OS_TENANT_NAME'], region_name=env['OS_REGION_NAME'], auth_system=auth_system, auth_plugin=auth_plugin)