[openstack-dev] [Heat] Referencing VPC resources across templates

Zane Bitter zbitter at redhat.com
Wed Apr 3 09:23:44 UTC 2013

On 03/04/13 09:29, Simon Pasquier wrote:
> Hi,
> Let say I have a first template to create a VPC network and another one
> to create a subnet associated to that VPC.
> <snip>
> I want to pass the VpcId value as a parameter to the second template but
> the stack creation fails. Looking at the code, this use case doesn't
> seem to be supported.
> Am I right? If yes, is it something planned for a future release?
> Thanks,
> Simon

You're correct that this is not supported (the VPC must be in the same 
template as the subnet). It also doesn't appear to be supported by AWS 
(the documentation is poor, but it looks like the property type is 
"Ref", not "String") so, unless that proves not to be the case, it's 
extremely unlikely that we would add support for it.

What AWS _does_ support is creating the subnet in the same template as 
the VPC and then passing the subnet ID to another template in the way 
you describe. Heat doesn't implement the SubnetId property on an 
Instance at all yet, but when it does this is something that ought to be 
allowed IMO.


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