Re: [ANNOUNCE] Git v2.16.0-rc0

[Jeff King <peff@peff.net>]

On Thu, Jun 14, 2018 at 09:20:33PM -0700, Jonathan Nieder wrote:

> What we've switched to is a versioned interface.  By setting
> GIT_SSH_VARIANT=simple, you are asking Git to promise to pass exactly
> <x> options.  If Git has a new option it wants to pass (like the "-o
> SendEnv" thing) but can live without it, then it can avoid breaking
> your wrapper and continue to follow this new promise.
> 
> The trouble is that GIT_SSH_VARIANT=simple is too... simple.  You
> would like a variant that passes in [-p port] [-4] [-6] as well.  We
> didn't implement that because we didn't have the attention of any
> wrapper writer who wanted it; in absence of a potential user, we
> decided to wait for a user to propose the interface they want.  Now we
> can celebrate, since that day has come.

I'm not sure I'm celebrating. It seems like work for not much benefit.
I'd just as soon use VARIANT=ssh and deal with any fallouts if my script
does not behave exactly like openssh in all regards.

> How would you like your ssh variant to work?  Some possibilities to
> get the thought process going:
> 
>  A. Would you want to set a variable 'GIT_SSH_SUPPORTS_OPTIONS=p46'
>     to inform Git about what options you support?

Not really. That just creates more work when I have to later use "op46"
to support "-o", even though my script already handles it fine (or
worse, since "-o" is open-ended).

>  B. Alternatively, what about a 'GIT_SSH_VARIANT=capabilities' variant
>     that calls "your-ssh-variant --capabailities" to get a
>     machine-readable list of capabilities it supports?

Not really. Now I have to implement this --capabilities thing. This is
literally a 10 line script.

>  C. Alternatively, would you like all parameters to come in on stdin,
>     credential helper style?

That's even worse. ;)

>  D. Other ideas?

I really am happy just saying "look, my script is basically openssh, so
just assume that". If it breaks, it breaks, and I'll fix it.

The one thing I was left puzzled by is why "-G" didn't work in the first
place, since the script really does just pass through its options.
Poking around, I think the problem actually _is_ the old ssh version
thing. I have a new one on my workstation, but our CI boxes are jessie,
and have openssh 1:6.7p1-5+deb8u4. And that's where I was digging into
the failure.

So sorry for misleading you earlier. The wrapper script looks like it's
a red herring to some degree (I guess its name not being "ssh"
contributed, but then the -G detection failed).

> If you were using an old version of OpenSSH, this would be a reason to
> revive the old patch, but I'm tempted to stall longer just to get more
> use cases like this to come out of the woodwork.

So apparently I am using an old version. Just switching to use "-V"
seems like it might be another solution, then.

-Peff