Exception occurred, ensure containers terminated.

[rpappalax]

Seems you can't quickly start another loadtest after terminating an attack cluster.
For some reason you have to wait a certain amount of time or AWS appears to tell the broker that the containers haven't terminated yet?

[2017-02-14 04:27:18,178][6130] Finished initializing: None.
[2017-02-14 04:28:06,378][6130] Msg: Running strategy: ad472bc4-e7ba-441c-aeba-9c0460d33731, ThreadID: 139717505046336
[2017-02-14 04:28:06,394][6130] Msg: Committed new session., ThreadID: 139717505046336
[2017-02-14 04:28:06,396][6130] Getting steps
[2017-02-14 04:28:06,398][6130] Exception occurred, ensure containers terminated.
Traceback (most recent call last):
  File "/home/ubuntu/git/loads-broker/loadsbroker/broker.py", line 431, in start
    yield self._initialize()
  File "/home/ubuntu/git/loads-broker/lib/python3.4/site-packages/tornado-4.4.1-py3.4-linux-x86_64.egg/tornado/gen.py", line 1015, in run
    value = future.result()
  File "/home/ubuntu/git/loads-broker/lib/python3.4/site-packages/tornado-4.4.1-py3.4-linux-x86_64.egg/tornado/concurrent.py", line 237, in result
    raise_exc_info(self._exc_info)
  File "<string>", line 3, in raise_exc_info
  File "/home/ubuntu/git/loads-broker/lib/python3.4/site-packages/tornado-4.4.1-py3.4-linux-   raise_exc_info(self._exc_info)
....
  File "/home/ubuntu/git/loads-broker/lib/python3.4/site-packages/tornado-4.4.1-py3.4-linux-x86_64.egg/tornado/concurrent.py", line 237, in result
    raise_exc_info(self._exc_info)
  File "<string>", line 3, in raise_exc_info
  File "/home/ubuntu/git/loads-broker/lib/python3.4/site-packages/tornado-4.4.1-py3.4-linux-x86_64.egg/tornado/gen.py", line 285, in wrapper
    yielded = next(result)
  File "/home/ubuntu/git/loads-broker/loadsbroker/aws.py", line 494, in _allocate_instances
    ami_id = get_ami(region, inst_type)
  File "/home/ubuntu/git/loads-broker/loadsbroker/aws.py", line 127, in get_ami
    raise KeyError(msg % (inst_type, list(instances.keys()), region))
KeyError: "Could not find instance type 'hvm' in [] for region us-east-1"
[2017-02-14 04:28:06,399][6130] Returning collections
[2017-02-14 04:28:06,399][6130] Got response of: True