[openstack-dev] [tripleo] When to use parameters vs parameter_defaults

Bogdan Dobrelya bdobreli at redhat.com
Fri Nov 10 09:27:14 UTC 2017


On 11/10/17 10:20 AM, Giulio Fidente wrote:
> On 11/26/2015 03:17 PM, Jiří Stránský wrote:
>> On 26.11.2015 14:12, Jiří Stránský wrote:
> 
> [...]
> 
>>> It seems TripleO is hitting similar composability and sanity limits with
>>> the top-down approach, and the number of parameters which can only be
>>> fed via parameter_defaults is increasing. (The disadvantage of
>>> parameter_defaults is that, unlike hiera, we currently have no clear
>>> namespacing rules, which means a higher chance of conflict. Perhaps the
>>> unit tests suggested in another subthread would be a good start, maybe
>>> we could even think about how to do proper namespacing.)
>>>
>>>
>>> Does what i described seem somewhat accurate? Should we maybe buy into
>>> the concept of "composable templates, externally fed
>>> hierarchy-transcending parameters" for the long term?
>>
>> I now realized i might have used too generic or Puppetish terms in the
>> explanation, perhaps drowning the gist of the message a bit :) What i'm
>> suggesting is: let's consider going with parameter_defaults wherever we
>> can, for the sake of composability, and figure out what is the best way
>> to prevent parameter name collisions.
> +1 I like very much the idea of parameter_defaults + strictier
> namespacing rules
> 
> Specifically regarding namespaces, puppet was great but ansible doesn't
> seem to be as good (at least to me), in fact I think we have chances for
> conflicts in both THT and the ansible playbooks
> 

Tripleo docs should have this explained, like in the ansible docs [1]

[1] 
http://docs.ansible.com/ansible/latest/playbooks_variables.html#variable-precedence-where-should-i-put-a-variable

-- 
Best regards,
Bogdan Dobrelya,
Irc #bogdando



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