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> On Wed, Mar 23, 2016 at 05:25:57PM +0300, Sergey Kraynev wrote:
> >    Hello,
> >    It looks similar on issue, which was discussed here [1]
> >    I suppose, that the root cause is incorrect using get_attr for your
> >    case.
> >    Probably you got "list"  instead of "string".
> >    F.e. if I do something similar:
> >    outputs:
> >      rg_1:
> >        value: {get_attr: [rg_a, rg_a_public_ip]}
> >      rg_2:
> >        value: {get_attr: [rg_a, rg_a_public_ip, 0]}
> >                      
> >      rg_3:
> >        value: {get_attr: [rg_a]}
> >      rg_4:
> >        value: {get_attr: [rg_a, resource.0.rg_a_public_ip]}
> >    where rg_a is also resource group which uses custom template as
> >    resource.
> >    the custom template has output value rg_a_public_ip.
> >    The output for it looks like [2]
> >    So as you can see, that in first case (like it is used in your example),
> >    get_attr returns list with one element.
> >    rg_2 is also wrong, because it takes first symbol from sting with IP
> >    address.
> 
> Shouldn't rg_2 and rg_4 be equivalent?

They are the same for template version 2013-05-23. However, they behave differently
from the next  version(2014-10-16) onward and return a list of characters. I think 
this is due to the fact that `get_attr` function mapping is changed from 2014-10-16.


2013-05-23 -  https://github.com/openstack/heat/blob/master/heat/engine/hot/template.py#L70
2014-10-16 -  https://github.com/openstack/heat/blob/master/heat/engine/hot/template.py#L291

This makes me wonder why would a template author do something like 
{get_attr: [rg_a, rg_a_public_ip, 0]} when he can easily do 
{get_attr: [rg_a, resource.0.rg_a_public_ip]} or {get_attr: [rg_a, resource.0, rg_a_public_ip]}
for specific resource atrributes.

I understand that {get_attr: [rg_a, rg_a_public_ip]} cane be useful when we just want to use
the list of attributes.


> 
> {get_attr: [rg_a, rg_a_public_ip]} should return a list of all
> rg_a_public_ip attributes (one list item for each resource in the group),
> then the 0 should select the first item from that list?
> 
> If it's returning the first character of the first element, that sounds
> like a bug to me?
> 
> Steve
> 
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