As I understand it, refreshonly ensures the command will only run when a
dependent object is changed, hence only subscribe and notify trigger it, not
require. So I don't think either exec would be called in your manifest. I might
be missing something there though.
But regardless, I'm not sure how you could get the exec to run before the
binary
is changed. As I understand it, if you use require without refreshonly, the
exec
resource will just be applied before the file resource regardless of whether
the
file is being changed or not. To only run the exec when the file is being
changed, you'd have to use refreshonly with notify or subscribe, or
independently determine that the file is about to be changed (possibly with an
onlyif command).
And if you do use refreshonly, with notify, it will only notify after the file
has changed I believe. Similarly a subscribe will only run the exec after the
file has changed. I don't think there's any way to notify an object that
something is about to change. Basically, notify is 'notify after', and AFAIK
there's no 'notify before'.
One option might be to stop and start the server every time regardless of
whether the file is being updated or not, but that seems less than ideal. An
expert may well be able to offer a better solution, but as a workaround I'd
suggest managing a copy of the server binary rather than the binary itself.
Then
have an exec type subscribed to the copy that, upon changes, stops the server,
copies the new binary over the old binary, and starts the server. It's not
particularly elegant, but it should definitely work and it's probably simpler
than trying to determine whether the file is about to change from within the
stop-server exec.
Rob
Mathew Binkley wrote:
> Hi. I'm hoping that someone can help me with a simple example. We
> are trying to use puppet to update a server binary to a group of
> machines. Here's pseudocode for what I'm trying:
>
> if (server_binary has changed) {
> 1) stop the old server
> 2) overwrite the old server binary by
> fetching the new server binary from puppet
> 3) start the new server
> }
>
> Below is the puppet manifest I wrote to handle this, but it isn't
> working properly. It is 1) downloading the new binary and then 2)
> stopping the server, which screws up our data. I've been looking
> through the documentation, and it isn't clear which permutation of
> before, require, subscribe, or notify is necessary to accomplish
> this. Hope someone can enlighten me. - Mat
>
>
> file { "/usr/local/sbin/server_binary":
> source => "puppet:///files/server_binary",
> require => Exec["stop-server"],
> before => Exec["start-server"]
> }
>
> # Stops the server
> exec { "/usr/local/sbin/stop-server":
> alias => "stop-server",
> refreshonly => true
> }
>
> # Starts the server
> exec { "/usr/local/sbin/start-server":
> alias => "start-server",
> refreshonly => true
> }
>
>
--
Robert Fay [EMAIL PROTECTED]
System Administrator office: 220
High Energy Physics Division tel (int): 43396
Oliver Lodge Laboratory tel (ext): +44 (0)151 794 3396
University of Liverpool http://www.liv.ac.uk/physics/hep/
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