def scale_down(config, instance_id):
"""Remove one instance from the environment and put it to the pool of stopped machines"""
logger = logging.getLogger(__name__)
if not scaling_down_possible(config):
logger.warning("Scaling down not possible, minimum number of instances is running")
else:
logger.info("Downscaling started.")
# Deregister it from load balancer
elb = aws_ec2_elb.get_load_balancer(config.get("region"), config.get("elb_name"))
elb.deregister_instances([instance_id])
# stop it
time.sleep(static.AUTOSCALE_DELAY_BEFORE_REMOVING_INSTANCE) # let instance respond to pending requests
instance = aws_ec2.get_instance(config, instance_id)
instance.stop()
# Update config
try:
instances = config.get_list("stopped_instances")
except ConfigParser.NoOptionError:
instances = []
instances.append(instance_id)
config.set_list("stopped_instances", instances)
instances = config.get_list("instances")
instances.remove(instance_id)
config.set_list("instances", instances)
logger.info("Downscaling completed. 1 instance stopped and is available in the pool.")
if len(instances) > 1:
logger.info("%d instances are currently on duty." % len(instances))
else:
logger.info("1 instance is currently on duty.")
def process_instance_state(config, state):
if state.instance_id in config.get_list('instances') and \
not state.state == 'InService' and \
not state.reason_code == 'Instance registration is still in progress.' and \
not state.reason_code == 'ELB':
id = state.instance_id
if unhealthy_instances.has_key(id):
num_checks = unhealthy_instances.get(id)
if num_checks + 1 == static.HEALTH_CHECKS:
logger.info('Stopping unhealty instance %s for investigation' %id)
unhealthy_instances.pop(id)
#Instance is considered failed and should be stopped for investigation
#Deregister it from load balancer
elb = aws_ec2_elb.get_load_balancer(config.get('region'),config.get('elb_name'))
elb.deregister_instances([id])
#stop it
instance = aws_ec2.get_instance(config,id)
instance.stop()
#Update config
instances = config.get_list('instances')
instances.remove(id)
config.set_list('instances',instances)
logger.info('Unhealthy instance is successfully stopped. ')
logger.info('A new instance instead of stopped one will be allocated automatically.')
else:
unhealthy_instances[id] = num_checks + 1
else:
unhealthy_instances[id] = 1
logger.warning('Instance %s is unhealthy with state %s and code %s' %(id, state.state, state.reason_code))
logger.warning('After %s checks it will be stopped.' % static.HEALTH_CHECKS)
def get_monitoring_information_from_start(config_id,instanceID,metric_q,statistic,unit):
config = Config(config_id)
cw = boto.ec2.cloudwatch.connect_to_region(config.get('region'))
metrics = cw.list_metrics(dimensions={'InstanceId': instanceID},
metric_name=metric_q)
if metrics:
inst = aws_ec2.get_instance(config, instanceID)
end_time = datetime.datetime.utcnow()
start_time=boto.utils.parse_ts(inst.launch_time)
#get nr of seconds
diff = end_time - start_time
seconds = diff.total_seconds()
#adjust the period
period=get_adjusted_period(seconds)
result = metrics[0].query(start_time,end_time,statistic,unit,period)
return sorted(result, key = operator.itemgetter(u'Timestamp'))
def scale_up_from_pool(config):
"""Scale up an instance from an available pool of previously stopped instances"""
logger = logging.getLogger(__name__)
# Launch instance
logger.info("Upscaling from the pool started.")
stopped_instance_id = config.get_list("stopped_instances")[-1]
instance = aws_ec2.get_instance(config, stopped_instance_id)
instance.start()
time.sleep(static.AUTOSCALE_DELAY_AFTER_START)
# Start httpd service
# Do not send instance directly as it does not have public DNS attached now, need to get it again from EC2
aws_ec2.start_httpd(config, instance.id)
# Register instance at load balancer
logger.info("Registering an instance at the load balancer")
elb = aws_ec2_elb.get_load_balancer(config.get("region"), config.get("elb_name"))
elb.register_instances([instance.id])
# Update config
instances = config.get_list("stopped_instances")
instances.remove(instance.id)
config.set_list("stopped_instances", instances)
instances = config.get_list("instances")
instances.append(instance.id)
config.set_list("instances", instances)
def test():
config = Config('100')
instance_id = 'i-3029b47b'
instance = aws_ec2.get_instance(config,instance_id)
pprint(vars(instance))
