[chef] Re: Re: Re: Re: Re: Re: deep merge - !merge users

[Matt Ray < >]

You just described how the firewall and ufw cookbooks work, they
depend on merging of attributes.

Thanks,
Matt Ray
Senior Technical Evangelist | Opscode Inc.

 
 | (512) 731-2218
Twitter, IRC, GitHub: mattray



On Thu, Dec 8, 2011 at 4:22 PM, Jay Feldblum 
<
 >
 wrote:
> Imagine a cookbook for implementing firewall rules, which inspected the node
> attributes to discover the rules, and was expected to be configured via
> roles. One role might want to append a rule, where each rule can include
> multiple source and destination interfaces, ip-addresses, protocols, port
> ranges, etc. Another node might want to append another rule, and a third
> role might want to update the first rule by appending e.g. an additional
> port range.
>
> Imagine the application or database cookbooks were implemented differently,
> where they inspected node attributes rather than searched data bags. The
> configurations for these are rather complex. Then one role might want to add
> a some data, while another role might want to update it; the first role
> providing blanket/default data, the second role being application-specific.
>
> Imagine fnichol's chef-rvm cookbook had default attributes that you don't
> like. You want your role to add the cookbook to the run-list but delete
> those default attributes, for example, delete the nested attribute that says
> ruby vX should be installed by default or gem Y should be installed by
> default in each ruby.
>
> - Jay Feldblum
>
>
> On Thu, Dec 8, 2011 at 10:45 AM, Bryan McLellan 
> <
 >
>  wrote:
>>
>> On Thu, Dec 8, 2011 at 10:03 AM, Jay Feldblum 
>> <
 >
>> wrote:
>> > But it is helpful when it comes to reusing third-party cookbooks: it
>> > permits
>> > writing custom roles to control and integrate with complex generic
>> > third-party cookbooks which look at deep attributes structures to decide
>> > what to do.
>>
>> Could you provide a specific example for others to follow to understand?
>>
>> Bryan
>
>