# Shef for recipe writing - maybe

**URL:** <https://discourse.chef.io/t/shef-for-recipe-writing-maybe/2157>\
**Category:** Chef Infra (archive)\
**Created:** [October 4, 2011, 11:03pm UTC](https://discourse.chef.io/t/shef-for-recipe-writing-maybe/2157 "2011-10-04T23:03:38Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Michael\_Glenney](https://avatars.discourse-cdn.com/v4/letter/m/a9adbd/32.png) [@Michael\_Glenney](https://discourse.chef.io/u/Michael_Glenney)\
**Post date:** [October 4, 2011, 11:03pm UTC](https://discourse.chef.io/t/shef-for-recipe-writing-maybe/2157/1 "2011-10-04T23:03:38Z")

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Hi,

I’m looking for some general help here as a chef n00b. I’m getting hung up  
while writing recipes with logic because I don’t know how to test my cases.  
For instance, in bash if I were going to write some lines that test for a  
variable or parses command output I’ll drop to the shell, run the command or  
set the variable, test, and verify I’m getting what I expect, then drop back  
into vi and write to that output. I’m getting lost while writing recipes  
because I don’t know how to do this (and maybe I shouldn’t)

For example, I have a recipe that I want to test if an attribute is set, if  
set do something, else, do something else. I know I can do:

if node.tomcat.attribute?(“folder”)  
do some stuff  
else  
do some other stuff  
end

But what I don’t know is how to test that attribute first, before committing  
that to a recipe. Generally, for ruby scripting, I do that in IRB. Was  
kind of hoping shef would provide that for me but I can’t get it to work  
like I think it should (and/or don’t understand how it should so I can  
change the way I do things). Another case might be verifying that an  
attribute has been overridden as expected.

I’ve tried dumping attributes from a node with ‘knife node show   
-F json \> somefile.json’ and then launching shef and importing those ‘shef  
-j somefile.json’ but I still don’t seem to be able to access my attributes.

I’ve tried ‘become\_node’ but limited success with that.

I’m not really seeking tech support here. More I’d like to hear from the  
people who are knee deep in chef every day. Is shef the IRB of Chef as I  
assumed it was? Do you know of any “best practices” guides or how-tos for  
writing recipes and the best tools/environment settings for doing so? Am I  
completely off in left field (aka, I’m looking at this all wrong)?

Thanks,

Mike G.

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**Author:** ![Joshua\_Timberman](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.chef.io/joshua_timberman/32/424_2.png) [@Joshua\_Timberman](https://discourse.chef.io/u/Joshua_Timberman)\
**Post date:** [October 5, 2011, 2:13am UTC](https://discourse.chef.io/t/shef-for-recipe-writing-maybe/2157/2 "2011-10-05T02:13:44Z")

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Hello!

On Tue, Oct 4, 2011 at 7:03 PM, Michael Glenney [mike.glenney@gmail.com](mailto:mike.glenney@gmail.com) wrote:

> But what I don't know is how to test that attribute first, before committing  
> that to a recipe. Generally, for ruby scripting, I do that in IRB. Was  
> kind of hoping shef would provide that for me but I can't get it to work  
> like I think it should (and/or don't understand how it should so I can  
> change the way I do things). Another case might be verifying that an  
> attribute has been overridden as expected.
> 
> I've tried dumping attributes from a node with 'knife node show   
> -F json \> somefile.json' and then launching shef and importing those 'shef  
> -j somefile.json' but I still don't seem to be able to access my attributes.

In Shef, you can enter the attributes context:

chef \> attributes  
chef:attributes \>

Which lets you apply attributes to the node object as though you were  
modifying a cookbook's attributes file.

If you want to operate on the node object as though in the context of a recipe:

chef \> recipe

Then use the set, default or override methods on the node object to  
set the attributes you want for testing purposes.

chef \> recipe  
chef:recipe \> node.set['tomcat']['folder'] = "/usr/local/tomcat"

To 'erase' the attribute value (e.g., test for non-extistence, simply  
set it to nil.

> I'm not really seeking tech support here. More I'd like to hear from the  
> people who are knee deep in chef every day. Is shef the IRB of Chef as I  
> assumed it was? Do you know of any "best practices" guides or how-tos for  
> writing recipes and the best tools/environment settings for doing so? Am I  
> completely off in left field (aka, I'm looking at this all wrong)?

Yes. Shef is an IRB console with a bunch of Chef classes already  
loaded. It can function in different contexts (attributes, recipe,  
main) and modes (solo, client, standalone). I probably use Shef daily  
in testing recipe development.

The wiki has:

[http://wiki.opscode.com/display/chef/Shef](http://wiki.opscode.com/display/chef/Shef)

We're working on adding a unit on Shef to the Chef Advanced training class.

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**Author:** ![Michael\_Glenney](https://avatars.discourse-cdn.com/v4/letter/m/a9adbd/32.png) [@Michael\_Glenney](https://discourse.chef.io/u/Michael_Glenney)\
**Post date:** [October 5, 2011, 5:58pm UTC](https://discourse.chef.io/t/shef-for-recipe-writing-maybe/2157/3 "2011-10-05T17:58:41Z")

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On Tue, Oct 4, 2011 at 7:13 PM, Joshua Timberman [joshua@opscode.com](mailto:joshua@opscode.com) wrote:

> Hello!
> 
> On Tue, Oct 4, 2011 at 7:03 PM, Michael Glenney [mike.glenney@gmail.com](mailto:mike.glenney@gmail.com)  
> wrote:
> 
> > But what I don't know is how to test that attribute first, before  
> > committing  
> > that to a recipe. Generally, for ruby scripting, I do that in IRB. Was  
> > kind of hoping shef would provide that for me but I can't get it to work  
> > like I think it should (and/or don't understand how it should so I can  
> > change the way I do things). Another case might be verifying that an  
> > attribute has been overridden as expected.
> > 
> > I've tried dumping attributes from a node with 'knife node show  
> >   
> > -F json \> somefile.json' and then launching shef and importing those  
> > 'shef  
> > -j somefile.json' but I still don't seem to be able to access my  
> > attributes.
> 
> In Shef, you can enter the attributes context:
> 
> chef \> attributes  
> chef:attributes \>

I was kind of hoping for a way to "assume" the attributes already on the  
node but I think what you described here may actually work out better  
because it gives me better control and allows me to test what I want to  
test. Thanks for your reply. I'll be trying this out today.

In my trial and error I thought what I would want is "become\_node". But I  
haven't been able to get that to work yet. I would start a separate thread  
to troubleshoot that but I don't know what I would use it for. have you  
found "become\_node" a useful feature in shef? If so what type of tasks is  
it useful for?

And let me be the first to vote for a rename of shef. It works well in  
writing but around the office we have to spell it out "Hey Bob, you should  
try to troubleshoot that recipe in s-h-e-f", "Does anyone have experience  
with this s-h-e-f tool?", etc. How about "chirb"? Or, keeping with the  
theme, "crockpot"? "wok"? 😉

> Which lets you apply attributes to the node object as though you were  
> modifying a cookbook's attributes file.
> 
> If you want to operate on the node object as though in the context of a  
> recipe:
> 
> chef \> recipe
> 
> Then use the set, default or override methods on the node object to  
> set the attributes you want for testing purposes.
> 
> chef \> recipe  
> chef:recipe \> node.set['tomcat']['folder'] = "/usr/local/tomcat"
> 
> To 'erase' the attribute value (e.g., test for non-extistence, simply  
> set it to nil.
> 
> > I'm not really seeking tech support here. More I'd like to hear from the  
> > people who are knee deep in chef every day. Is shef the IRB of Chef as I  
> > assumed it was? Do you know of any "best practices" guides or how-tos  
> > for  
> > writing recipes and the best tools/environment settings for doing so? Am  
> > I  
> > completely off in left field (aka, I'm looking at this all wrong)?
> 
> Yes. Shef is an IRB console with a bunch of Chef classes already  
> loaded. It can function in different contexts (attributes, recipe,  
> main) and modes (solo, client, standalone). I probably use Shef daily  
> in testing recipe development.
> 
> The wiki has:
> 
> [http://wiki.opscode.com/display/chef/Shef](http://wiki.opscode.com/display/chef/Shef)
> 
> We're working on adding a unit on Shef to the Chef Advanced training class.

MG

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**Author:** ![Brad\_Knowles](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.chef.io/brad_knowles/32/716_2.png) [@Brad\_Knowles](https://discourse.chef.io/u/Brad_Knowles)\
**Post date:** [October 5, 2011, 7:10pm UTC](https://discourse.chef.io/t/shef-for-recipe-writing-maybe/2157/4 "2011-10-05T19:10:54Z")

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On Oct 5, 2011, at 12:58 PM, Michael Glenney wrote:

> And let me be the first to vote for a rename of shef. It works well in writing but around the office we have to spell it out "Hey Bob, you should try to troubleshoot that recipe in s-h-e-f", "Does anyone have experience with this s-h-e-f tool?", etc. How about "chirb"? Or, keeping with the theme, "crockpot"? "wok"? 😉

I always thought that the pronunciation should be "shee-eff".

But with Ruby being "rb", and Interactive Ruby being "irb", if we were to follow the same model with chef, then we would have "ichef-client" or somesuch. Another alternative might be "chefsh". I tried translating "test kitchen" into a variety of other languages but didn't hit on any good solutions. Certain languages like Japanese and Korean weren't in an ASCII-readable format, so I have no idea what they actually might have said.

--  
Brad Knowles [bknowles@ihiji.com](mailto:bknowles@ihiji.com)  
SAGE Level IV, Chef Level 0.0.1