On Thursday, April 2, 2015 at 10:33:02 AM UTC-5, Thomas Hallgren wrote:
>
> John,
>
> The HI-14's requested behavior was not implemented as an afterthought. On
> the contrary. Since all facts have been available in the top scope since
> Puppet 3.5, there was simply no need for a specific handling of facts in
> Hiera and the approach taken was very deliberate. We knew that whatever we
> would put in place would be applicable for all variables in the scope. We
> also knew that since scope variables are not the only structured data out
> there, it would be somewhat congested to create solution that would work
> *only* with scope variables but not with everything else. I think that
> would have been a really bad decision and as far as I can remember it was
> never brought up to discussion.
>
>
Am I misspelling of the word "interpolation", or something? Is it too
similar to the word "interpretation" that I have been using to talk about
how hiera translates keys into corresponding values? I'm getting
frustrated here.
I have not suggested that the new feature should have been restricted to
facts specifically or even to variables generally. Although HI-14 uses
facts as its examples, the text is not so restrictive, and I agree that
such a solution would have been awkward. No, I am saying that the change
should have been restricted to the context of interpolation tokens, on
account of that being the only context contemplated by the feature
request. Protestations notwithstanding, that aspect of the change has
clearly gotten little love, even though it is both the actual intended
target and by far the most important part. It provides for doing things
with Hiera that were difficult or impossible to do before.
The change to key interpretation, on the other hand, is largely a solution
without a problem, and, moreover, without any request or change approval
that I have seen. I probably wouldn't be so on about it if it did not
constitute a breaking change, but I find it pretty concerning that a
breaking change is introduced without request, approval, or any particular
justification other than possibly that it was more convenient to make the
change than to avoid making it. Mustering up some charity, I am prepared
to believe that the changes were implemented based mostly on the ticket
title, without an effective analysis of the actual problem as set forth in
the description text. That's only a possible explanation, though, not a
justification.
The current solution works with:
>
> %{scope('some.dotted.key')}
>
Yes.
>
> and
>
> %{hiera('some.dotted.key')}
>
Why?
>
> and
>
> Hiera.lookup('some.dotted.key')
>
Why?
>
> The interpolated hiera lookup is implicitly doing the last one so they
> need to come as a package.
>
Fine, the last two need to come as a package, but why did either one need
to come at all? What would have been the problem with, say,
%{hiera('some').dotted.key}
or
%{hiera('some')[dotted][key]}
or any of probably a dozen other alternatives? Surely wherever
Hiera.lookup('some.dotted.key') now returns an object,
Hiera.lookup('some')['dotted']['key'] always did return that same object.
My apologies. Please feel no obligation to respond to those
implementation-directed comments. With the interpolation angle actually
covered (its total lack of documentation notwithstanding), my concern is
now much more with how and why the change ended up exceeding its requested
scope than with the details of change itself. The merits of the change to
key semantics aside, that change should not have been implemented under the
auspices of HI-14 as it is written.
In the end, of course, PL's change management processes are none of my
responsibility. I am speaking from the perspective of a concerned
bystander with a vested interest in Puppet and PuppetLabs remaining strong
and effective, and playing fast and loose with the change management
process is not supportive of continuing effectiveness. Frankly, at this
point I am even more more concerned that no one seems to want to
acknowledge that there even was a problem with how this went down than I am
with the fact that it did go down. But if I am whistling in the wind, then
so be it.
John
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