Open Stack

On 30/07/14 02:21, Anant Patil wrote:
> On 28-Jul-14 22:37, Clint Byrum wrote:
>> Excerpts from Zane Bitter's message of 2014-07-28 07:25:24 -0700:
>>> On 26/07/14 00:04, Anant Patil wrote:
>>>> When the stack is updated, a diff of updated template and current
>>>> template can be stored to optimize database.  And perhaps Heat should
>>>> have an API to retrieve this history of templates for inspection etc.
>>>> when the stack admin needs it.
>>>
>>> If there's a demand for that feature we could implement it, but it
>>> doesn't easily fall out of the current implementation any more.
>>
>> We are never going to do it even 1/10th as well as git. In fact we won't
>> even do it 1/0th as well as CVS.
>>
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>
> Zane,
> I am working the defect you had filed, which would clean up backup stack
> along with the resources, templates and other data.
>
> However, I simply don't want to delete the templates for the same reason
> as we don't hard-delete the stack. Anyone who deploys a stack and
> updates it over time would want to view the the updates in the templates
> for debugging or auditing reasons.

As I mentioned, and as Ton mentioned in another thread, the old 
templates are useless for auditing (and to a large extent debugging) 
because the update process turns them into Frankentemplates that don't 
reflect either the old or the new template supplied by the user (though 
they're much closer to the new than the old).

So if you don't delete them, then you don't end up with a copy of the 
old template, you end up with a broken copy of the new template.

> It is not fair to assume that every
> user has a VCS with him to store the templates.

It most certainly is fair to assume that.

In addition, Glance has an artifact repository project already underway 
with the goal of providing versioned access to templates as part of 
OpenStack.

It's likely that not all users are making use of a VCS, but if they're 
not then I don't know why they bother using Heat. The whole point of the 
project is to provide a way for people to describe their infrastructure 
in a way that _can_ be managed in a VCS. Whenever we add new features, 
we always try to do so in a way that _encourages_ users to store their 
templates in a VCS and _discourages_ them from managing them in an ad 
hoc manner.

> It is kind of
> inconvenience for me to not have the ability to view my updates in
> templates.

I tend to agree that it would be kind-of nice to have, but you're 
talking about it as if it's a simple matter of just not deleting the old 
template and sticking an API in front of it, rather than the major new 
development that it actually is.

> We need not go as far as git or any VCS. Any library which can do a diff
> and patch of text files can be used, like the google-diff-match-patch.

We don't store the original text of templates - in heat-engine we only 
get the object tree obtained by parsing the JSON or YAML. So the 
templates we store or could store currently are of not much use to 
(human) users.

cheers,
Zane.