In a customized OpenStack training, the client asked for an example of using the Python code to create an instance, here I want to share how to do it.

Basically the script consists of the following steps:

1. Import the python client library
2. Get the authentication information
3. Create a client object by passing the authentication parameters
4. Use the client object to perform different operations

Let me show you the code for each step.

Import the python client library

from novaclient import client

Get the authentication information

Create a dictionary variable and get the credential information from corresponding environment variables.

def get_nova_creds():
    d = {}
    d['username'] = os.environ['OS_USERNAME']
    d['api_key'] = os.environ['OS_PASSWORD']
    d['auth_url'] = os.environ['OS_AUTH_URL']
    d['project_id'] = os.environ['OS_TENANT_NAME']
    return d

Create a client object by passing the authentication parameters

creds = get_nova_creds()
nova = client.Client('2.0',**creds)

Use the client object to perform different operations

Once you create the Nova client object, you can use it to find out information (such as image, flavor etc.) that are required to launch a new instance. Following shows an example:

image = nova.images.find(name="cirros-0.3.4-x86_64")
flavor = nova.flavors.find(name="m1.tiny")
network = nova.networks.find(label="mynet2")

Now you can use the client object to launch an new instance:

server = nova.servers.create(name = "myinstance4",
                                 image = image.id,
                                 flavor = flavor.id,
                                 nics = [{'net-id':network.id}],
                                 )