Cannot use default AZ with volume

[Zane Bitter]

The AvailabilityZone property of as AWS::EBS::Volume resource is required. The correct way to supply it is almost invariably by doing:

  {"Fn::GetAtt": ["MyInstance", "AvailabilityZone"]}

for the AWS::EC2::Instance it needs to be attached to. The AvailabilityZone attribute of the instance is obtained from the AvailabilityZone property, which is *optional*.

In the case where the AvailabilityZone of the Instance is not specified, we should pass None as the availability_zone value to Cinder to force it to use the default. Instead we are passing an empty string ('').

[Zane Bitter (zaneb)]

The ideal fix here would be to actually return the name of the default AZ from Instance.FnGetAtt('AvailabilityZone') even when it is not explicitly supplied as a property.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/39753

[Zane Bitter (zaneb)]

Steve B: is this ^ the right fix, or do we need to reconsider how we treat None when resolving references? I'm wondering how many similar cases might be lurking :/

[Steve Baker (steve-stevebaker)]

see comment in review

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/39753
Committed: http://github.com/openstack/heat/commit/8ede7612a0fcf56fbce2ac392812de51f2ccb878
Submitter: Jenkins
Branch: master

commit 8ede7612a0fcf56fbce2ac392812de51f2ccb878
Author: Zane Bitter <email address hidden>
Date: Thu Aug 1 17:22:18 2013 +0200

    Make Volumes work with the default AvailabilityZone

    The most common way to specify an AvailabiltyZone for a volume is to grab
    it from the Instance it is going to be attached to:

        "AvailabilityZone" : {"Fn::GetAtt": ["WikiDatabase",
                                             "AvailabilityZone"]},

    But the first unit tests to check the value passed to Cinder for the AZ,
    introduced in 134b11ccd145f982b7173bc9a5d0f1bc3e8eef8c, just forced the
    value instead of obtaining it from the Instance.

    Add a unit test to check the common case, and fix the resulting error (an
    empty string is returned instead of None).

    Fixes bug #1207416

    Change-Id: I83ea2f3f0c417eb9e97abdf27a9eaffd441cb070