Re: Config spec for git

> On Wed, Nov 17 2021, Wallace, Brooke T (US 349D-Affiliate) wrote:
>
>> Has any one considered adding a config spec feature to Git or does Git alreadt have some way to support the same features?
>>
>> I've been using Git for a while now for small projects but taking on a
>> new larger project I've come to realize that Git does not have config
>> specs and so seems to be missing an important feature for managing
>> large projects.
>>
>> We use configuration specs to select directories from a common code
>> base (repo) and map them into different baselines to creat multiple
>> product builds with different feature sets. We used this feature in
>> VCSs such as Clearcase and Perforce. Ultimately this allows us to
>> manage the repo in one directory structure and create product builds
>> with a different one. For example the repo has multiple directories
>> for different products/targets, but a baseline, the workspace, has
>> only one target directory always with the same name mapped to the same
>> location. Obviously the corresponding directories in the repo have
>> different names.
>>
>> Git supports the notion of submodules, but I see no way to map a
>> submodule directory to a different name, remove unwanted subdirs of a
>> submodule, or map a submodule over a subdirectory of the primary
>> repo. Config specs also allow you to specify a specific branch or
>> version that you want to map to your workspace independent of other
>> directories, branches and versions.
>>
>> I suppose it may be possible to achieve the same result by treating
>> the primary repo as the configspec. But I feel like there are some
>> features config specs support that i do not have using submodules, but
>> might need down the road.
>>
>> I can see that omitting, obscuring, or overwriting parts of a repo
>> would not play well with the commit id. So I imagine there could be
>> some real complications trying to add support for the notion of a
>> flexible config spec.
>>
>> Appreciate any comments/feedback
> I understand all the terms involved in your E-Mail except "config spec",
> so on the first couple of readings I was thoroughly confused.
>
> I gather from some Google searching that you may be referring to
> ClearCase SCM jargon:
> https://en.wikipedia.org/wiki/Rational_ClearCase#The_configuration_specification
> &
> https://www.ibm.com/docs/en/rational-clearcase/8.0.0?topic=views-how-config-spec-works
>
> From your description it seems like you're talking about some
> combination of the work-in-progress "sparse checkout" feature, and a
> feature to compose arbitrary subdirectories and overlays of existing
> repositories.
>
> As far as I know nobody's working on the latter, although I suppose some
> clever combination of submodules and sparse checkouts might make it
> possible.
>
> All of that's really a shot in the dark, I think I'm probably not the
> only one who'd benefit from a description of what you'd expect a "config
> spec" to do for you that doesn't assume pre-existing knowledge of the
> term.
>
> More generally it's a very common initial migration stategy between
> SCM's and X SCM -> Git in particular to first consider how you could 1=1
> map existing behavior to Git.
>
> Those sorts of migrations are generally much more painful in the longer
> term than considering how you'd map the software or assets you have to
> Git if you were starting out today, which may be something to think
> about.