Use fabric with dynamic auto scaling

fab_ec2.py

def web_cluster():
    env.user = 'ubuntu'
    env.key_filename = ['mykey.pem']
    env.conftype = 'prod'
    env.project = 'sample'

    ec2conn = ec2.connection.EC2Connection(AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY)
    web_group = ec2conn.get_all_security_groups(groupnames=['web'])
    for i in web_group[0].instances():
        hostname = i.__dict__['public_dns_name']
        if hostname is not '':
            env.hosts.append(hostname)