'Initialize EBS block device API instance.
:param _EC2 ec2_client: A record of EC2 connection and zone.
:param UUID cluster_id: UUID of cluster for this
API instance.'

def __init__(self, ec2_client, cluster_id):

    self.connection = ec2_client.connection
    self.zone = ec2_client.zone
    self.cluster_id = cluster_id
    self.lock = threading.Lock()
