On Thu, Aug 26, 2010 at 1:02 PM, Luke Kanies <[email protected]> wrote:
> On Aug 26, 2010, at 12:47 PM, Nigel Kersten wrote:
>
>> On Thu, Aug 26, 2010 at 12:43 PM, Luke Kanies <[email protected]> wrote:
>>> On Aug 26, 2010, at 12:42 PM, Nigel Kersten wrote:
>>>
>>>> On Thu, Aug 26, 2010 at 12:08 PM, Rein Henrichs <[email protected]> 
>>>> wrote:
>>>>> Excerpts from Nigel Kersten's message of Thu Aug 26 11:27:25 -0700 2010:
>>>>>> So I feel that it would be immensely useful for Facter to optionally
>>>>>> store a certain amount of historical data about the fact evaluation.
>>>>>>
>>>>>> It would be great to be able to simply interrogate info like "when did
>>>>>> the amount of RAM in this machine change?" "what is my kernel version
>>>>>> history?" etc etc.
>>>>>
>>>>> Yes, this would be very useful. That said, it's not that we need Facter
>>>>> to store historical data. We need *something* to store historical data.
>>>>> Probably not Facter. Probably an inventory service. Probably something
>>>>> that provides a rich query interface, like CouchDB.
>>>>
>>>> But if we're considering adding a ttl/caching for facts, aren't we
>>>> talking about Facter storing historical data anyway?
>>>
>>> Adding a ttl isn't actually the same as doing the caching - that is, a 
>>> given fact may want to define its own ttl for downstream users (i.e., 
>>> Puppet) without actually doing any caching.
>>
>> So in that case you may get a different value for a fact when running
>> the Facter binary than when that same fact is used by Puppet? Doesn't
>> that seem suboptimal?
>
> It might be, but in that case you should set your ttl to zero.  If you're 
> comfortable with a long ttl, then it shouldn't matter, right?

It shouldn't matter, but it creates an situation that can make
debugging difficult, unless the plan is for facter --puppet
invocations to give you an accurate view of what Puppet actually sees.

> I guess the question is if there needs to clearly be a direct linkage in 
> facter between that server-side view and the client-side view, and my 
> perspective is, not really.
>
> I've always thought of facter as a means of collecting data and as little 
> else as possible.  In fact, the first use of Facter was sticking its output 
> in an ldap db, and I wrote a separate tool (enhost) for that, rather than add 
> additional functionality to Facter.

I think this restricts the utility of Facter to a point where it may
as well simply be part of Puppet.


>
>>>> Luke's next mail he says:
>>>>
>>>> "Would it be acceptable if, say, the puppet agent provided a simple
>>>> interface to the server-side fact storage, which will already have
>>>> this?  We're working on designing something like this right now,
>>>> although it's more mental goo than real ideas right now"
>>>>
>>>> This would be ok, but how on earth does this work with load-balancing?
>>>> You have no guarantee that you're hitting the same
>>>> local-to-the-server fact store when interrogating.
>>>
>>> The server-side storage would need to be centralized, which has to be done 
>>> for other reasons anyway.
>>>
>>> --
>>> I think that's how Chicago got started.  A bunch of people in New York
>>> said, 'Gee, I'm enjoying the crime and the poverty, but it just isn't
>>> cold enough. Let's go west.'         --Richard Jeni
>>> ---------------------------------------------------------------------
>>> Luke Kanies  -|-   http://puppetlabs.com   -|-   +1(615)594-8199
>>>
>>>
>>>
>>>
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>>
>>
>>
>> --
>> nigel
>>
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>
>
> --
> The advantage of a classical education is that it enables you to
> despise the wealth that it prevents you from achieving.
>    -- Russell Green
> ---------------------------------------------------------------------
> Luke Kanies  -|-   http://puppetlabs.com   -|-   +1(615)594-8199
>
>
>
>
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-- 
nigel

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