Re: [PATCH v2 0/2] setup.c: make bare repo discovery optional

From: Glen Choo <chooglen@google.com>
Date: May 16, 2022, 18:36 UTC
Message-ID: <kl6ly1z1iati.fsf@chooglen-macbookpro.roam.corp.google.com>
In-Reply-To: <xmqqy1z12zxr.fsf@gitster.g>

Junio C Hamano <gitster@pobox.com> writes:

Show 13 quoted lines

> "Glen Choo via GitGitGadget" <gitgitgadget@gmail.com> writes:
>
>>  * die()-ing is necessary if we're trying to flip the default value of
>>    discovery.bare. We'd expect many bare repo users to be broken, and it's
>>    more helpful to fail loudly than to silently ignore the bare repo.
>>
>>    But in the long term, long after we've flipped the default and users know
>>    that they need to opt into bare repo discovery, would it be a better UX
>>    to just silently ignore the bare repo?
>
> Would a middle-ground of giving a warning() message help?  Can it be
> loud and annoying enough to knudge the users to adjust without
> breaking the functionality?

Personally, when my tool changes its behavior, I would strongly prefer it to die than to "change behavior + warn". I'd feel more comfortable knowing that the tool did nothing as opposed to doing the wrong thing and only being informed after the fact. Also, I sometimes ignore warnings ;)

When we _do_ transition away from die(), ignore + warning() sounds like a good first step.

But if any of this flies in the face of the project's conventions, let me know as such.

Show 5 quoted lines

>>      +    Add a config variable, `discovery.bare`, that tells Git whether or not
>>      +    it should work with the bare repository it has discovered i.e. Git will
>>      +    die() if it discovers a bare repository, but it is not allowed by
>
> Missing comma before "i.e."

Thanks.

Show 12 quoted lines

>>      +++
>>      ++The currently supported values are `always` (Git always recognizes bare
>>      ++repositories) and `never` (Git never recognizes bare repositories).
>>      ++This defaults to `always`, but this default is likely to change.
>>      +++
>>      ++If your workflow does not rely on bare repositories, it is recommended that
>>      ++you set this value to `never`. This makes repository discovery easier to
>>      ++reason about and prevents certain types of security and non-security
>>      ++problems, such as:
>
> Hopefully "git fetch" over ssh:// and file:/// would run the other
> side with GIT_DIR explicitly set?

Ah, I'll check this and get back to you.

>                                                        I do not yet
> find these "problems, such as..." so convincing.

What would be a convincing rationale to you? I'll capture that here.

I'm assuming that you already have such an rationale in mind when you say that the longer-term default is that "we respect bare repositories only if they are the cwd.". I'm also assuming that this rationale is something other than embedded bare repos, because "cwd-only" does not protect against that.

Perhaps "never" sounds better to folks who don't ever expect bare repositories and want to lock down the environment. Randall (cc-ed) suggests one such use case in [1].

(To Randall: Oops, I actually meant to cc you earlier, since you were the first to suggest a practical use case for never allowing bare repos. It must've slipped my mind).

[1] https://lore.kernel.org/git/005d01d84ad0$782e8fc0$688baf40$@nexbridge.com.