From Chef Summit 2013

1. Cookbook Reusability
Noah Kantrowitz
Balanced, Inc

2. The problem
Community cookbooks only
do 90% of what you need.

4. New Problem
•
Complex contribution process.
•
Forking during iteration.
•
Proliferation of special cases.

5. Wrapper Cookbooks
•
Overriding attributes.
•
chef-rewind, here be dragons.
•
Extension by prepend/append.

6. Requirements
• Responsive effort:
5% change
~5% work
• Documented extension mechanism.
Integration with kitchen, berks, etc.
•

7. DevOps

8. LWRPs?
•
Still only prepend/append.
•
No substitution except rewind.
•
Better, but not by much.

9. Enter: Classes
class Chef
class Resource::Something < Resource
...
end
class Provider::Something < Provider
...
end
end

10. Chef::Resource
def initialize(*args)
super
@resource_name = :something
@action = :enable
@allowed_actions = [
:enable, :disable
]
end

11. Chef::Resource
def path(arg=nil)
set_or_return(:path, arg, {
kind_of: String
})
end

12. Chef::Provider
def load_current_resource
end
def whyrun_supported?
true
end
def action_enable
...
end

13. Why?
•
• No really, subclassing!
Allows detailed, responsive
•
Subclassing.
customization.

14. Verbosity
• A lot of boilerplate code.
Missing some LWRP DSL goodies.
•

15. Poise

16. Poise
class Resource::Something < Resource
include Poise
...
end
class Provider::Something < Provider
include Poise
...
end

17. LWRP-ese
class Resource::Something < Resource
include Poise
actions(:enable, :disable)
attribute(:path, kind_of: String)
end

18. Notifying Block
def action_enable
notifying_block do
...
end
end

19. Include Recipe
def action_enable
include_recipe 'something'
end

20. Lazy Defaults
class Resource::Something < Resource
include Poise
attribute(:path,
default: lazy { node['path'] }
)
end

21. Option Collector
class Resource::Something < Resource
include Poise
attribute(:database,
option_collector: True)
end

22. Option Collector
something 'one' do
database host: 'a', port: 8000
end

23. Option Collector
something 'one' do
database do
host 'a'
port 8000
end
end

24. Sub-resources
class Resource::Something < Resource
include Poise(container: true)
end

25. Sub-resources
class Resource::Foo < Resource
include Poise(parent: Something)
end

26. Sub-resources
something 'one' do
...
foo 'asdf' do
...
end
end

27. Sub-resources
something 'one' do
...
end
foo 'asdf' do
parent 'one'
end

28. Sub-resources
something 'one'
foo 'asdf'

29. Distribution
• Cookbooks?
• Gems?