[chef] Re: Duelling resources

[Adam Jacob < >]

There are none. 

Resources (and their actions) promise to ensure that each resource is in the 
correct state at that moment in the run. If, for some reason, you actually 
*wanted* to install a package, run a command from it, then uninstall the 
package, Chef won't pretend to know better than you. This is the same thing 
that makes more complicated use cases, like installing mysql on ec2 (where 
the workflow is "install package, stop service, format EBS, mount EBS, 
configure mysql, start service") easy to do.

If you wanted some reporting here, you could get it from a custom report 
handler that walks the resource collection looking for duplicate names, and 
prints them out.

Best,
Adam

-- 
Opscode, Inc.
Adam Jacob, Chief Product Officer
T: (206) 619-7151 E: 

 


On Wednesday, August 31, 2011 at 5:59 PM, Matt Palmer wrote:

> How do people handle duelling resources, like the following trivial example:
> 
>  package "foo" do
>  action :remove
>  end
> 
>  package "foo" do
>  action :install
>  end
> 
> I would expect that to error out, or at least pick the last version
> and run with it, but no, on every run I get:
> 
>  [Thu, 01 Sep 2011 10:37:46 +1000] INFO: Removing package[foo]
>  [Thu, 01 Sep 2011 10:37:48 +1000] INFO: Installing package[foo]
> version x.y.z
> 
> Swapping the resources swaps the log messages and the end state.
> 
> Now, I'm well aware that having two conflicting packages defined
> side-by-side like this isn't likely in the real world, and even a
> direct disagreement of "this package should/shouldn't be installed" is
> similarly unlikely in a system. I'll note that a similar result is
> observed with template resources, which are *far* more likely to
> suffer from this sort of disagreement. It's *certainly* possible in
> the real world (with manifests consisting of thousands of resources,
> from cookbooks written by separate groups of people), that there will
> be some amount of disagreement, and it'd be nice if Chef provided a
> bit more protection. What methods and practices are there to
> minimise, or preferably detect and warn the user of this sort of
> warfare?
> 
> - Matt