[openstack-dev] [heat] update_allowed vs. immutable

Jason Dunsmore jason.dunsmore at rackspace.com
Mon May 2 18:00:45 UTC 2016

Hi Praveen,

The docs you referred to in the plugin guide is for the resource property attributes - they have nothing to do with parameters.  This is an important distinction because there is also an "immutable" parameter attribute.

The "immutable" property attribute was added because an equivalent to AWS' "Updates are not supported" functionality was needed:



From: Praveen Yalagandula <ypraveen at avinetworks.com>
Sent: Monday, May 2, 2016 11:55 AM
To: OpenStack Development Mailing List
Subject: [openstack-dev] [heat] update_allowed vs. immutable

What is the difference between "update_allowed" and "immutable" parameters for a property? According to the plugin guide at

True if an existing resource can be updated, False means update is accomplished by delete and re-create. Default is False.

True means updates are not supported, resource update will fail on every change of this property. False otherwise. Default is False.

Since any resource can be deleted and then re-created, it seems "update_allowed" is the right parameter to define. Why do we need "immutable"?

Praveen Yalagandula
Avi Networks
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