On Apr 19, 8:26 am, Felix Frank <felix.fr...@alumni.tu-berlin.de>
wrote:
> On 04/19/2011 03:18 PM, jcbollinger wrote:
[...]
> > The bottom line as far as our discussion goes, however, is that it is
> > *intentional* that the yum Package provider fails to remove packages
> > on which other installed packages depend, and that there is good
> > technical justification for that design choice. I would be surprised
> > if other Package providers were different in that regard. Your Puppet
> > manifests need to account for that, one way or another.
>
> I disagree.
>
> First off, the apt provider *will* recursively uninstall depending packages.
That's an unfortunate inconsistency between providers. I am
surprised.
Oddly enough, I found bug 1739, closed on 0.24.x, that makes exactly
the change from "rpm -e" to "yum -y remove". That would make the yum
provider work like the apt provider. I didn't find anything
suggesting that it was reverted, yet the change is not present in the
released code.
> Second, this *is* sound design. If I tell puppet that I don't want
> package "X" on my system, I expect it to remove it and do whatever is
> necessary, except the provider's backend objects.
I didn't say that behavior such as the apt provider's is unsound or
unjustified, rather I said that the Yum provider's behavior is
intentional (my deduction) and justified. When there is justification
for two incompatible alternatives, a design decision must be made, and
it was made -- inconsistently -- for the Package providers.
> It is your opinion that a package manager should object as soon as a
> depended package would be removed by an uninstallation.
It is my opinion that it is *reasonable* for a Puppet Package provider
refuse to remove a package on which others depend instead of removing
all dependencies along with it. It is _not_ my opinion that the
alternative would be _un_reasonable. Both approaches have advantages
and disadvantages.
It is less reasonable, however, that providers are inconsistent in
this regard.
> Myself, I don't
> want to be bothered with such details. I fully expect my package manager
> do care about all aspects of dependeny resolution, be it during
> installation or its opposite.
That's fair. But consider this:
package { "foo":
ensure => absent
}
package { "i-depend-on-foo":
ensure => latest
}
The manifest is inherently inconsistent, yet if the Package provider
performs automatic dependency installation and removal then it can be
applied without error. The result depends on which package is managed
first, and at least one of the packages will flip-flop between being
installed and uninstalled. The specified configuration can never be
achieved. If I had that situation in one of my manifests, I would
want an error message.
John
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