[chef] Re: Re: Re: Re: Environment Cookbook Patterns & Questions

[Torben Knerr < >]

My favorite approach is to use a "top-level cookbook". A top-level
cookbook roughly represents a VM. It is essentially the same as an
"environment cookbook" but uses metadata.rb for locking the dependency
graph rather than environments.

This lets you use environments for representing your infrastructure
environments rather than (ab?)using them for locking dependency
graphs. The only cookbook dependency you have in the environment is
the one to the top-level cookbook (all others come in transitively via
metadata.rb).

Related discussions:
 * http://lists.opscode.com/sympa/arc/chef/2014-01/msg00419.html
 * http://lists.opscode.com/sympa/arc/chef/2014-06/msg00173.html

Examples:
 * https://github.com/tknerr/sample-toplevel-cookbook
 * https://gist.github.com/tknerr/4e3236d00ceba917abea

Word of caution: I'm using this with chef-solo and have not checked
whether this way of keeping metadata.rb and Berksfile.lock in sync
(https://gist.github.com/tknerr/4e3236d00ceba917abea) works with
chef-client too. If not, you might want to us a generative approach
instead.

HTH,
Torben

On Mon, Jan 5, 2015 at 12:04 AM, Matt Juszczak 
<
 >
 wrote:
> Agreed!! Thanks for the help! It's worth mentioning that "poise-appenv"
> seems to try to solve this problem.
>
> Matt
>
> On Jan 4, 2015, at 7:08 AM, Christine Draper
> <
 >
>  wrote:
>
> Matt,
>
> Your analysis makes a lot of sense to me. We need a way to separate the
> inherent variances between infrastructure environments as one dimension; and
> the through-time release ("code") variances as another.
>
> Christine
>
> On Sat, Jan 3, 2015 at 10:09 PM, Matt Juszczak 
> <
 >
>  wrote:
>>
>> Christine,
>>
>> > It makes sense to me to create a base 'myface' cookbook that knows how
>> > to set up the logical components of the application like database 
>> > servers,
>> > application servers, the actual application code etc.  I'd consider this 
>> > to
>> > be an application cookbook, one that you could then reuse in multiple
>> > contexts (e.g. the different production data centers).  Perhaps it might
>> > even be reused in different lifecycle phases (prod, staging, systest).
>> >
>> > The above might become an environment cookbook if you use it to lock
>> > down the cookbook versioning for actual deployments.
>>
>> Gotcha. So in this case, the application cookbook and environment cookbook
>> are *literally* the same thing and you don’t have BOTH. An application
>> cookbook simply becomes an environment cookbook once a Berksfile.lock is
>> checked in. Jamie mentions that application cookbooks and environment
>> cookbooks don’t differ much, except to me it’s been unclear whether having
>> an environment cookbook for an app replaces the functionality of the
>> application cookbook all-together (simply by now having a Berksfile.lock in
>> revision control). I think I got it now.
>>
>> > In your case it sounds like intend the east and west data centers to be
>> > part of one overall production environment and want to keep them in sync
>> > from a cookbook (and application software) version perspective. If so, 
>> > the
>> > environment cookbook could be 'myface-prod' and consist of little more 
>> > than
>> > a berksfile.lock plus attributes to customize the application cookbook
>> > specifically for prod environment.
>>
>> I’m thinking we would make our environment cookbooks *code environments*
>> only. In other words, while a prod environment might have static attributes
>> that differ from a staging environment and will *always* differ, it seems
>> the environment cookbook pattern that Jamie describes is about managing an
>> SDLC. You apply version 1.0.1 of a cookbook to your staging environment, 
>> and
>> eventually that makes its way to prod. Therefore, to me, it makes sense to
>> have a “myface” environment cookbook that can be versioned, and utilize the
>> berkflow tool to promote different versions of that cookbook through chef
>> server environments.
>>
>> But that still doesn’t solve the problem of *infrastructure environments*
>> (IE: configuration that applies to servers in the staging environment but
>> never the prod environment and vice versa). For example, if you deploy
>> version 1.0.0 of myface to staging, you’re eventually going to deploy that
>> to production. However, if you deploy changes to “staging environment
>> configuration” (perhaps network addresses?), you likely aren’t going to 
>> copy
>> those configuration parameters to production any time soon. That
>> configuration is strictly for the staging infrastructure environment!
>>
>> So…
>>
>> > The key question is how you can then add in the 'east' and 'west' data
>> > center variances. Environment files for myface-prod-east and
>> > myface-prod-west would seem a decent option, if the variances are fairly
>> > simple attribute differences, and particularly if the variances were
>> > relatively independent/orthogonal to the application (e.g. updating
>> > networking information for one data center is relatively independent of
>> > changes to the myface application). You'd likely want to version the
>> > environment definitions externally in source control.  You may need to
>> > coordinate cookbook changes with environment changes, in the case where 
>> > an
>> > application change requires networking changes in the two data centers.
>>
>> Based on your feedback, and the more I think about this, the more I think
>> it does make sense to create more environment files in chef server and
>> maintain them in revision control. These environment files would contain
>> both application (managed by berkflow) and infrastructure environment
>> configuration options (such as network configuration). Therefore, we would
>> likely create something like:
>>
>> myface-prod-us-east
>> myface-prod-us-west
>> myface-staging-us-east
>> myface-staging-us-west
>>
>> and use berkflow to manage version pinning:
>>
>> blo upgrade myface-prod-useast myface
>> blo upgrade myface-prod-uswest myface
>>
>> ...and simply build a wrapper tool to upgrade all “prod” environments at
>> once that calls blo upgrade numerous times. Meanwhile, the environments
>> above (myface-prod-useast) have specific configuration for servers in that
>> environment, such as network configuration.
>>
>> Thanks for your insight. I’m still curious to hear some other opinions but
>> it’s good to know others have been confused on this and I’m not missing
>> something simple.
>>
>> -Matt
>
>