knife exec search configurable directories

Attempted to implement this. It seems to work but comments are welcome. Pull request sent:

https://github.com/opscode/chef/pull/183

Details:
This adds a key called script_path in the chef config that takes an array of paths to look for knife exec scripts. It defaults to an empty array to mimic existing behavior. If you set a path in your knife.rb, it'll be searched in cases where the specified script isn't found in the current directory. Has debug logging. It doesn't support ~ expansion in the script paths, which is true of other paths in the knife config (I think).

After some refactoring, it adds some extra error handling that is a bit more graceful and ~ expansion in paths is supported.

If you prefer, this is the execdir branch on my github:

https://github.com/kcbraunschweig/chef/tree/execdir

I think it could be a good feature. In my workflow I almost always create directory 'script' in chef repo and after that when I'm inside it I can do calls like

knife exec script/deploy "nodes-query"

I'm removing the fix_version of 0.10.6. That will be set when this is merged (likely to 0.10.8)

We currently keep our knife exec scripts in CHEF-REPO/knife, but I could see CHEF-REPO/scripts as well. We should set a standard though and look for a similar directory in .chef/knife or .chef/scripts as well.

This would establish a best practice. If the choice isn't obvious to you upon consideration, please ask around a bit on the mailing list now, but I don't feel strongly on either choice.

Allowing the other paths is great, but we should cover most scenarios out of the box.

So by default you would want it to find from BOTH chef-repo/foo and ~/.chef/foo or should one supersede the other? If both, then if the specific script exists in both, which one wins? Not really asking what you want so much as if these sorts of things already have a pattern in other commands you could point me at. I poked around a little but not sure what represents "standard" precedence for this type of case, which is why I just left it out entirely. Happy to add it in though.

Yeah, I think it should look first in $chef-repo/scripts then in .chef/scripts.

Both of these directories should be determined automatically, the same as we do now. I maintain multiple .chef directories for different hosted chef organizations and chef servers. If I'm in ~/chef/opscode-btm/cookbooks/apache2 and I run 'knife exec magic.rb' it should run it from ~/chef/opscode-btm/.chef/scripts/magic.rb.

I don't recall if it is possible to determine where $chef-repo is. Maybe "#{cookbook_path}/../scripts" ?

Committed an update that adds default script paths as requested. I think this is ready to merge now. Too bad I didn't get in gear before 0.10.10.

config[:script_path] ||= Chef::Config[:script_path]
# should be:
config[:script_path] ||= Array(Chef::Config[:script_path])

Just in case the user sets this to a string in the config, we don't want to blow up.

Otherwise good to go and marked for merge.

Merged to master.