Launch an ec2 instance and then wait until they're ready

launchec2.py

import sys
import boto
import boto.ec2

def _launchAWSInstances():
    connection = boto.ec2.connect_to_region(AWS_REGION, aws_access_key_id = AWS_ACCESS_KEY_ID, aws_secret_access_key=AWS_ACCESS_KEY_SECRET)
    global reservation
    reservation = connection.run_instances(AWS_AMI,
        key_name=AWS_SSH_KEY_NAME,
        instance_type=AWS_INSTANCE_SIZE,
        security_groups=[AWS_SECURITY_GROUP])
    import time
    unixtime = int(time.time())

    for index, instance in enumerate(reservation.instances):
            instance.add_tag('Name', 'UDB Machine ' + str(unixtime))

    print "Awaiting Instances Ready"
    for index, instance in enumerate(reservation.instances):
            _awaitAWSInstanceReady(instance, 0)
    print "All Instances Ready"

# takes an ec2 instance object
# recursively calls itself until it's ready
def _awaitAWSInstanceReady(instance, loops):
    time_interval = 1
    if instance.update() == 'running':
        time_elapsed = loops * time_interval
        print ''
        print 'Took %d seconds' % time_elapsed
        return True
    else:
        _progressBar(loops)
        time.sleep(1)
        _awaitAWSInstanceReady(instance, loops + 1)

# simple progress bar
def _progressBar(state):
    progress_bar = '=' * state
    sys.stdout.write('\r'+progress_bar)
    sys.stdout.flush()