Extra instance is created if evaluation period set short

[Hang Liu]

If evaluation period is set shorter than the instance starting time. And 'repeat_actions' is set to True.
Extra instances would be created, even the cooldown time has been set long enough.

Possible Reasons:

    1) No guarding logic at alarm signals in ASG code.
    2) If the 2nd instance starts up slow, a 2nd alarm may arrive before the 2nd instance is ready.
    3) The very first 'cooldown' timestamp is not computed/set because the 2nd instance is not ready. So the 3rd instance (maybe the 4th, 5th, ... instances are quickly launched).

[Deliang Fan (vanderliang)]

Should we add a para to indicate the status of ASG, for example, PROGRESS, COMPLETE. If the status of ASG resource is process autoscaling, then any signal will be ignored. Only if that the ASG status is COMPLETE and out of cool down time can scale.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/186659

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/kilo
Review: https://review.openstack.org/202660

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/202660
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=034c58261194eacfc320e9174d4240e12224cd66
Submitter: Jenkins
Branch: stable/kilo

commit 034c58261194eacfc320e9174d4240e12224cd66
Author: yanyanhu <email address hidden>
Date: Fri May 29 01:43:03 2015 -0400

    ASG scaling account for cooldown timestamp & in-progress

    There are cases where it takes a long time to create a new resource as
    requested by the scaling operation on an ASG resource, for instance, a
    nova server creation followed by a complex SoftwareDeployment. During
    this process, additional alarms may come in but failed to be blocked
    by the current cooldown checking mechanism because the very first
    timestamp has yet to be generated. This is leading to unexpected size
    adjustment to the ASG.

    This patch augments the existing cooldown checking mechanism with a
    scaling-in-progress test so that additional alarms arriving during
    the very first scaling operation will be ignored.

    Closes-Bug: #1375156

    Conflicts:
     heat/engine/resources/openstack/heat/scaling_policy.py
     heat/scaling/cooldown.py
     heat/tests/autoscaling/test_heat_scaling_group.py
     heat/tests/autoscaling/test_heat_scaling_policy.py
     heat/tests/autoscaling/test_scaling_group.py
     heat/tests/autoscaling/test_scaling_policy.py

    (cherry-picked from b76881b8bcb3e381c5b993a0c84afd37abd8ea5b)
    Change-Id: Ib8aa83eed366df7097c9cbb9247eca866ae4b620

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/juno
Review: https://review.openstack.org/224753

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/juno
Review: https://review.openstack.org/231798

[OpenStack Infra (hudson-openstack)]

Change abandoned by Zane Bitter (<email address hidden>) on branch: stable/juno
Review: https://review.openstack.org/224753
Reason: I finally got this working, so to reduce future confusion I reproposed with the correct Change-Id at https://review.openstack.org/#/c/231798/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/231798
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=e182a57c9a8ba2f5f4203fac3d2aa04d45dffb5e
Submitter: Jenkins
Branch: stable/juno

commit e182a57c9a8ba2f5f4203fac3d2aa04d45dffb5e
Author: yanyanhu <email address hidden>
Date: Thu Sep 17 09:29:50 2015 -0400

    ASG scaling account for cooldown timestamp & in-progress

    There are cases where it takes a long time to create a new resource as
    requested by the scaling operation on an ASG resource, for instance, a
    nova server creation followed by a complex SoftwareDeployment. During
    this process, additional alarms may come in but failed to be blocked
    by the current cooldown checking mechanism because the very first
    timestamp has yet to be generated. This is leading to unexpected size
    adjustment to the ASG.

    This patch augments the existing cooldown checking mechanism with a
    scaling-in-progress test so that additional alarms arriving during
    the very first scaling operation will be ignored.

    Change-Id: Ib8aa83eed366df7097c9cbb9247eca866ae4b620
    Co-Authored-By: Zane Bitter <email address hidden>
    Closes-Bug: #1375156