EC2 + Boto + Fabric

tasks.py

def create_new_fetcher():
	conn = EC2Connection(settings.AWS_ACCESS_KEY_ID, settings.AWS_SECRET_ACCESS_KEY)
	image = conn.get_image(settings.AWS_FETCHER_IMAGE_ID)
	new_reservation = image.run(key_name='zumur', security_groups=['zumur.fetcher'], instance_type='t1.micro')
	new_instance = new_reservation.instances[0]
	conn.create_tags([new_instance.id], {"Name": 'Fetcher', 'zumur.role':'fetcher'})
	return True

@task()
def cycle_fetchers():
	print "Checking fetchers"
	key_name = os.path.join(settings.PROJECT_ROOT, 'keys', 'zumur.pem')
	conn = EC2Connection(settings.AWS_ACCESS_KEY_ID, settings.AWS_SECRET_ACCESS_KEY)
	reservations = conn.get_all_instances()
	one_down = False
	valid_fetchers = 0
	for reservation in reservations:
		for instance in reservation.instances:
			if 'zumur.role' in instance.tags and instance.tags['zumur.role'] == 'fetcher' and instance.tags['Name'] == 'Fetcher' and instance.state == 'running':
				# Make sure the fetcher is running. Restart it.
				valid_fetchers += 1
				with fabric_settings(user='ubuntu', key_filename=key_name, host_string=instance.public_dns_name):
					run('/home/ubuntu/zumur/zumur-fetcher/bin/startup.sh -daemon', warn_only=True)
				one_hour_ago = datetime.datetime.now() - datetime.timedelta(minutes=60)
				if date_parse(instance.launch_time).replace(tzinfo=None) < one_hour_ago.replace(tzinfo=None) and one_down == False:
					print "... Spinning up/down a fetcher"
					create_new_fetcher()
					one_down = True
			if 'zumur.role' in instance.tags and instance.tags['zumur.role'] == 'fetcher' and instance.tags['Name'] == 'Fetcher':
				if instance.state == 'pending':
					valid_fetchers += 1
	if valid_fetchers < settings.AWS_FETCHER_COUNT:
		print "... need to launch %s fetchers" % (settings.AWS_FETCHER_COUNT - valid_fetchers)
		for i in xrange(0, settings.AWS_FETCHER_COUNT - valid_fetchers, 1):
			print "... Spinning up a fetcher"
			create_new_fetcher()