Hi all,
I kinda expect blank stares in response to this question, but I'll do
what I can to both describe what I'm trying to do and to do it in an
interesting way.
One of the things I've always wanted Puppet to be able to do is to
track changes of resources without having to actually manage a given
resource. For instance, I want to be able to say:
file { "/etc/passwd": check => content }
And get an event if that file's content changes, even though I'm not
specifying its content. This specific case actually worked until
0.25, but only for file content, and even then, only by specifying
'check => checksum'. Something in 0.25 broke this, though, so I'm
trying to fix it, and at the same time make it more general.
I've just converted the checksum property to a parameter (in my
refactor/master/checksum_as_parameter branch, imaginitively enough),
which mostly just removed the now-non-functional code in the checksum
parameter and made the rest of the content/checksum/source interaction
considerably cleaner.
So, life is better but we still don't have out-of-band change tracking.
It's clear we now need something at the framework level - the system
needs special support for this, rather than coding it into a parameter
- and I'm thinking the right answer is to have something akin to noop,
but comparing to previous state rather than desired state.
This obviously is a structural change and thus, most likely, a
sizeable change, so I want to make sure I'm on the right track.
Unless it's a straightforward change, I'm not at all sure I'll be
trying to get this done in the near future -- there's a lot of low-
hanging fruit with a higher-priority -- but I'd like to have it in my
head how it will work, anyway.
In looking at how noop is implemented -- we just return a noop event
instead of doing any work -- we should be able to return a similar
event ("out_of_band_change" or something). The primary difference is
that, with this, we have to track the state of every parameter for
which we're doing this. This has always been the primary purpose of
the 'state' file, and in general it shouldn't be a huge leap to start
tracking this, but it's worth pointing out, anyway.
One point worth making is that this definitely has to be done on top
of my other event work, which means it'd never work in the 0.25 line.
Comments? Fears?
--
Now and then an innocent man is sent to the legislature.
--Kin Hubbard
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Luke Kanies -|- http://reductivelabs.com -|- +1(615)594-8199
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