Tuesday, September 30, 2014

Using python to connect remotely to Openstack

In order to beef up my DevOps skills I decided to see if I could connect through a REST API using python. I found out that there are some python modules built specifically for this.

One such module is called novaclient. You would need pip on your machine to do this.

sudo easy_install pip

Then you can use pip to install the nova client.

sudo pip install python-novaclient

If you want to look at the details of the python module it can be found here:


This is where I look more into the code and found out it’s capabilities

You can pass parameters to the “client” function.

def __init__(self, username=None, api_key=None, project_id=None,
auth_url=None, insecure=False, timeout=None,
proxy_tenant_id=None, proxy_token=None, region_name=None,
endpoint_type='publicURL', extensions=None,
service_type='compute', service_name=None,
volume_service_name=None, timings=False, bypass_url=None,
os_cache=False, no_cache=True, http_log_debug=False,
auth_system='keystone', auth_plugin=None, auth_token=None,
cacert=None, tenant_id=None, user_id=None,
connection_pool=False, session=None, auth=None,

First I built a login function that will pass these parameters which I can call from my main script.

def get_nova_credentials():
 cred =  {}
 cred['username'] = "admin"
 cred['api_key'] = “password”
 cred['auth_url'] = "http://<openstack-ip>:5000/v2.0"
 cred['project_id'] = "demo"
 cred['service_type'] = "compute"
 return cred

Now in my main script I can import the client and my credentials

#!/usr/bin/env python

import novaclient
from novaclient.v1_1 import client
from login import get_nova_credentials
credentials = get_nova_credentials()

#Pass credentials to the client function.

nova = client.Client(**credentials)

#grab the list of servers and print out the id, names and status

vms = nova.servers.list(detailed=True)
for vm in vms:
  print vm.id, vm.name, vm.status

script in action.

laptop$ python server-list.py 
f5801333-5d81-496c-b257-e589ca36e944 Cirros-VM2 ACTIVE
098270e0-e5fb-4ea6-a1f1-2dfca11a409d Cirros-VM1 ACTIVE

So what's the big deal? Why do this when you can use the Horizon web ui?

Now that I have a basic understanding of this module, I can start automating things such as building VMs, virtual networks, etc in a scaled and precise manner.

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