Re: [PATCH] docs: clarify that credential discards unrecognised attributes

[M Hickford <mirth.hickford@gmail.com>]

On Tue, 25 Oct 2022 at 00:59, Jeff King <peff@peff.net> wrote:
>
> On Mon, Oct 24, 2022 at 07:57:48AM +0000, M Hickford via GitGitGadget wrote:
>
> > It was previously unclear how unrecognised attributes are handled.
>
> Yeah, this was always part of the intended behavior, but I agree we did
> not say it very explicitly (aside from an in-code comment!). Both the
> intent and content of your patch look good to me.

Thanks. What happens next? I should look for this change in the seen
branch? https://git-scm.com/docs/MyFirstContribution#after-approval

> We did discuss patches a long time ago that would let Git carry
> arbitrary keys between helpers, even if Git itself didn't understand it.
> One of the intended uses was to let helpers talk to each other about
> TTLs. So if you had say:
>
>   [credential]
>   helper = generate-some-token
>   helper = cache
>
> where the first helper generates a token, and the second caches it, the
> first one could shove a "ttl" or "expiration" key into the protocol,
> which the cache could then learn to respect.

Composing helpers like this is how I encourage users to configure
git-credential-oauth [1][2]. Note that the storage helper should come
*before* the generator, so that `credential fill` finds a stored
credential before it generates a fresh credential.

> the first one could shove a "ttl" or "expiration" key into the protocol,
> which the cache could then learn to respect.
>
> But we never merged such a thing, and in practice I think people would
> just implement both parts as a single helper for simplicity.

Composing helpers has the advantage that the user can choose their
preferred storage. Generated credentials aren't necessarily short
lived. GitHub OAuth tokens, for example, are good for at least one
year [3].

[1] https://lore.kernel.org/git/CAGJzqs=+fCQzkDX53H8Mz-DjXicVVgRmmzPjkatSiOpYO7wGGA@mail.gmail.com/
[2] https://github.com/hickford/git-credential-oauth
[3] https://docs.github.com/en/authentication/keeping-your-account-and-data-secure/token-expiration-and-revocation#token-expired-due-to-lack-of-use