Re: git 2.16, Jenkins git client plugin, and ""

From: Bryan Turner <bturner@atlassian.com>
Date: Jan 25, 2018, 00:31 UTC
Message-ID: <CAGyf7-Hb+w23sbW8rZxmLXBDO-+kBDFwirN3siSNwveYdX4qPg@mail.gmail.com>
In-Reply-To: <CAM2y_jWnpDSA8kE+9z1jKW0dCzjOz053HrD479qc0ZjL13Gabw@mail.gmail.com>

On Wed, Jan 24, 2018 at 3:55 PM, Mark Waite <mwaite@cloudbees.com> wrote:

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> It appears that git 2.16.0 and 2.16.1 have introduced a change which
> surprises the Jenkins git client plugin.
>
> Git 2.16.0 and 2.16.1 on Linux both report "fatal: ssh variant
> 'simple' does not support setting port" when used in the context of
> the Jenkins git client plugin.

We noticed a similar issue in Bitbucket Server's tests, related to us using a wrapper script with the GIT_SSH variable. Some further discussion is available in [1].

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>
> The solution we've accepted into the git client plugin source code is
> to set the environment variable "GIT_SSH_VARIANT=ssh".  That allows
> the failing case to pass, and does not seem to harm older versions of
> git.
>
> The documentation at https://git-scm.com/docs/git says that
> GIT_SSH_VARIANT "overrides Git’s autodetection whether
> GIT_SSH/GIT_SSH_COMMAND/core.sshCommand refer to OpenSSH, plink or
> tortoiseplink."
>
> I haven't seen the same message from Git 2.16.1 for Windows.

Our Windows builds didn't seem to fail for this either, which was interesting.

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>
> The Jenkins bug report
> (https://issues.jenkins-ci.org/browse/JENKINS-49111) describes the
> user experience.
>
> Is the GIT_SSH_VARIANT solution expected to be used by git consumers
> like the Jenkins git client plugin when passing credential information
> through environment variables like SSH_ASKPASS?

The expectation seems to be that if you use GIT_SSH or GIT_SSH_COMMAND, you'll also use GIT_SSH_VARIANT to tell Git what to expect, because it doesn't (shouldn't?) make assumptions, starting in 2.16, that your custom SSH uses OpenSSH syntax.

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>
> I see "ssh", "plink", and "tortoiseplink" as values of GIT_SSH_VARIANT
> used in tests, and "auto", "putty", and "simple" used in the source
> code in addition to "ssh", "plink", and "tortoiseplink".  What are the
> allowed values for GIT_SSH_VARIANT?
>
> What is the recommended value so that the Jenkins git client plugin
> can remain most compatible with previous behavior?

"ssh" is probably the most compatible, because I'm pretty sure prior to 2.16 that behavior was the assumed behavior.

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>
> No value was assigned previously to GIT_SSH_VARIANT in the Jenkins git
> client plugin.  I was expecting that git would choose "ssh" as the
> default value for GIT_SSH_VARIANT, rather than apparently choosing
> "simple".
>
> Is this a bug, or is this the new, intentional behavior of git?

It's intentional. There was some discussion (again, see [1]) about whether the change needed further changes, but it doesn't appear any further changes were made.

>
> Thanks,
> Mark Waite

[1]: https://public-inbox.org/git/CAGyf7-FQp4q2vvH1ponQvmVDTu0hiMSK1JKytQZ4O1i0MCnz7g@mail.gmail.com/

Hope this helps! Bryan