[chef] Re: Roles and Versioning

[Bryan Berry < >]

hey Kevin,

I recommend reading Adam Jacob's comments on my "Gangnam Style" post. 

In his argument for roles he essentially says that roles should be used as aliases to a run_list and do your best to keep data out of them. I can live w/ that use of roles, because they are friendlier to search for.

Call me crazy but I think we are rapidly approaching consensus that you should use generic cookbooks for the generic part of your configuration - whether or not u ever open-source them - and put the data and tweaks that drive the generic cookbook in an application cookbook. That said, this consensus may only exist in my head :)

My advice, listen closely to whatever Peter Donald and Jamie Winsor say or write

On Tue, Nov 20, 2012 at 7:31 PM, Kevin Christen < " target="_blank"> > wrote:

Here's a scenario for the use of roles and cookbooks in Chef server that confuses me. I'd like to know how the community handles this situation. Imagine that I have a cookbook "foo" at version 1.0.0 with a single recipe "bar". I define a role "foo_host" with "recipe[foo::bar]" in its run_list. 

Now imagine that I improve the "foo" cookbook by adding a "baz" recipe and increment it's version number to 1.1.0. What do I do with the role? If I add the new recipe to the "foo_host" run_list, I will break any nodes that won't use the latest version of the cookbook because of an environment version constraint. I can only think of a few solutions:

• Version the role through its name. In other words, leave "foo_host" alone and create a "foo_host_1" role with both recipes in its run_list.
  
• Run separate versions of chef server for each environment, as mentioned here. Update the role in only those servers who's environment will pick up the latest version of the cookbook.
• Don't use a role for this purpose. Instead, define a separate, versioned "wrapper" cookbook as described by Bryan Berry here.

Is there a community consensus on how to deal with this situation?

Thanks,

Kevin Christen