Comments prefixed with [aa] (outlook goes nuts with HTML formatted messages)
From: crowbar-bounces On Behalf Of Judd Maltin Sent: Thursday, March 07, 2013 2:07 PM To: Ralf Haferkamp Cc: crowbar Subject: Re: [Crowbar] Attribute injection Hi Ralf! > a) With pure Chef - via the default attributes in the cookbook, the > environments facility of Chef, or roles > > b) In Crowbar - crowbar will compute and inject override values for > these attributes, at runtime, via chef API's. Just out of curiousity. How will that be done? Will crowbar create roles with the attributes via the API or directly assigne the attributes to the node objects? Or is there another approach? [aa] - Both in crowbar 1.0 and 2.0 the idea is to use the Chef rest API, via the Ruby classes in the chef gem. > c) In other deployment systems - in a manner either like a) or b) or > telepathically. ^^^^^^^^^^^^^^ I'd like to see the source code for that :) FWIW, telepathy will not be necessary. Andi omits in option (a) a very common pattern for many Chefs - "data bags." In fact, data bags are generally preferred over roles for attribute injection. I'd recommend that we create an "eventual consistency knob" pattern. It would allow the user to dial in "search," "data_bag," or "Crowbar" as desired. More coming on my blog soon.. soon. -judd [aa] - Judd , imho there are a few issues with switching from node/role attributes to databag based values: * There are no clear override semantics for data bags - you specify the values in one place, and that's it. There a few cases where we rely on the ability to set a safe default, and then override it on node-specific basis when needed. * The changes to the existing recipes are much larger. Rather than say something like node["nova"]["api"]["endpoint"], you'd have to go load the databag, find the item and use it. At this point, neither rcp, att or crowbar uses a databag based pattern. I would suggest we keep changes relative to CB1.0 to a minimum around the mapping of attributes to chef data, so we can ship this thing. _______________________________________________ Crowbar mailing list Crowbar@dell.com https://lists.us.dell.com/mailman/listinfo/crowbar For more information: http://crowbar.github.com/
