[chef] Re: Re: Re: Re: Re: More on Cookbook Design Patterns

[Lamont Granquist < >]

On Thu Apr  3 13:38:12 2014, Jason Perry wrote:
> What I'm also following is that it's probably not a good idea to combine the application cookbook with a role 
> cookbook.  Currently our application cookbooks have replaced the roles runlist setting where previously the role 
> would have a run list that was something like 
> "recipe[acme_java],recipe[tomcat],recipe[groovy],recipe[myapp]" with the role being called 
> "myapp".  Now the myapp default recipe has a bunch of include_recipe calls and the role now just has 
> "recipe[myapp]".  When the node is bootstrapped the run list ends up looking like so 
> "role[datacenterA],role[base],role[myapp]".  In this model I would have to move whatever the base role is 
> doing down to the myapp::default recipe level or parts of it for testing.  I think this is probably the most tricky 
> part of  it all and how to avoid too many dependencies with still being able to test the cookbooks purpose.
>
>    -- Jay

i'd suggest that all roles do is map 1-1 with role cookbooks.  then i'd 
suggest that recipe[myapp] be pretty thin and it would just setup some 
attributes to point at the instance of the software to deploy and then 
include_recipe something like "acme_tomcat_server".  the 
acme_tomcat_server recipe would be more complicated and would express 
all the dependencies including pulling in the your java cookbook, and 
the actual tomcat cookbook along with monitoring and whatnot.  you 
might want to have this export an LWRP that your myapp cookbook could 
use rather than have it be attribute-driven.

then if installing java requires setting up an internal corporate yum 
repo mirror then you would want to break that out into its own recipe 
and include_recipe it there in the java cookbook.  you might also 
include_recipe this from the base role cookbook as well, but that's 
fine.  chef will figure that out and the yum repo will get setup before 
anything that depends on it.   if you're doing your testing correctly 
and expressing your dependencies correctly then you shouldn't have any 
issues with this.  myapp will pick up the tomcat_server cookbook which 
will pickup the java cookbook which will pickup your yum repo cookbook 
(even if your base role comes after your role cookbook it should still 
work out fine so long as you've tested your myapp cookbook in isolation 
and it has passed -- although generally i'd suggest that base comes 
first so that your user accounts get setup early so you can login to 
servers and troubleshoot -- but the further down the 
test-driven-infrastructure road you get, hopefully the less likely this 
is a real concern).