Re: [PATCH] http: add custom hostname to IP address resolves

From: Junio C Hamano <gitster@pobox.com>
Date: May 4, 2022, 14:34 UTC
Message-ID: <xmqqzgjxnz73.fsf@gitster.g>
In-Reply-To: <CAP8UFD0hWUudP6pZVGS5yOVCjbBCm1LdK_EbrsQp9KiVPPMCyA@mail.gmail.com>

Christian Couder <christian.couder@gmail.com> writes:

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>> The above is a reasonable summary of CURLOPT_RESOLVE documentation
>> that is appropriate to have here for those of us who are not
>> familiar with it.  For those of us who may want to learn more, it
>> would help to have an URL to the canonical documentation page, e.g.
>> https://curl.se/libcurl/c/CURLOPT_RESOLVE.html but it is not
>> required.  People should be able to find it easily.
>
> Yeah, I also thought that it wasn't required, but I will add it
> anyway, as I agree it could be useful and hopefully it doesn't change
> very often.

Ah, I didn't consider the URL going stale at all. Forcing readers to look for the keyword certainly is a way to avoid it, but they will do that once they realize URL went stale, so there is not a strong incentive to avoid recording the now-current URL, I would think.

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>> > +http.hostResolve::
>>
>> Is "host" a good prefix for it?
>>
>> In the context of HTTP(s), if there is no other thing than host that
>> we resolve, "http.resolve" may be sufficient.  For those who are
>> looking for CURLOPT_RESOLVE equivalent, "http.curloptResolve" may
>> make it easier to find.
>
> I am Ok with just "http.resolve". I think using "curlopt" is perhaps
> going into too many details about the implementation of the feature,
> which could theoretically change if we ever decided to use something
> other than curl.

You may want to step back a bit and rethink.

Even if we decide to rewrite that part of the system not to depend on cURL, end-user facing documented interface, i.e. how the mappings are given to the system, will stay with us, and it is clear that it was modeled after CURLOPT_RESOLVE---well, it was stolen from them verbatim ;-).

So we may wean ourselves off of cURL, but CURLOPT_RESOLVE will stay with us for this particular feature.

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>> I am wondering if we want to mention the expected use case here
>> as well, something like
>>
>>     This is designed to be used primarily from the command line
>>     configuration variable override, e.g.
>>
>>         $ git -c http.resolve=example.com:443:127.0.0.1 \
>>             clone https://example.com/user/project.git
>>
>> perhaps?  Not a suggestion, but soliciting thoughts.
>
> I am also interested in others' thoughts about this. If no one thinks
> that a config option could be useful, I am Ok with making it a
> "--resolve" command line option that can be passed to any Git command
> similar to "-c <name>=<value>":
>
> git --resolve=... <command> [<args>]

Absolutely not.

"git [push|fetch|clone|ls-remote] --dns-pre-resolve=..." that is *NOT* git wide, but is only for transport commands might be a possibility, but even then, you'd need to invent a way to do the same for non cURL transports (we want to be able to pin the IP when going over SSH to a certain host, for the same reason) if we promote it to an officially supported command line option.

Unless we do that, it is probably better to leave it as an obscure configuration meant to help server operators. At least, with the name of the configuration variable prefixed with http.*, we have a valid excuse when somebody complains "the feature does not do anything for git:// transport".

Thanks.