Burkholder, Peter wrote: > I just finished listening to the Configuration Management panel from > OSBridge (on blip.tv). > > Near the end of it, Adam Jacob states that Puppet's resource dependency > ordering is non-deterministic, > and that manifests that work fine 19 times will fail the 20th time. > > Is this true? I'm puzzled that what Luke considers one of Puppet's > strong suits is derided by > others as its Achille's heel. >
There is a change in 0.25.0 that I also should have mentioned because it
impacts this discussion.
In 0.25.0 we've added a 'require' function. The doco is here:
"Evaluate one or more classes, adding the required class as a dependency.
The relationship metaparameters work well for specifying relationships
between individual resources, but they can be clumsy for specifying
relationships between classes. This function is a superset of the
'include' function, adding a class relationship so that the requiring
class depends on the required class.
.. Warning:: using require in place of include can lead to unwanted
dependency cycles. For instance the following manifest, with 'require'
instead of 'include' would produce a nasty dependence cycle, because
notify imposes a before between File[/foo] and Service[foo]::
class myservice {
service { foo: ensure => running }
}
class otherstuff {
include myservice
file { '/foo': notify => Service[foo] }
}
"
This takes some of the (potential) pain out of the ordering by allowing
class level dependencies. This adds dependency resolution higher than
between individual resources. It doesn't solve issues where you haven't
built the right dependencies at a resource level but does provide more
flexibility.
This isn't the same as Chef - as Adam has pointed out Chef has top-down
ordering rather than Puppet's dependency graph - but I think it'll make
life easier for some people.
Regards
James Turnbull
--
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