Re: SSH in git-fetch

[Leo Prikler]

Hello Peter,

Am Dienstag, den 13.07.2021, 22:38 +0800 schrieb Lo Peter:
> Dear all,
> 
> I am experimenting with writing a package definition for an example R
> package (https://github.com/jennybc/foofactors) in a PRIVATE channel,
> where the R source is also at a PRIVATE github repository.
> While the private channel works with proper setup of SSH key (that
> needs to be in PEM format due to a bug in libssh2), I am having
> trouble with the private git repository for package source.
> 
> Is it that git-fetch does not support fetching over SSH?
Indeed, git-fetch does not support fetching over SSH.

> The package definition I have is:
> 
> (define-module (my-packages r-pkgs)
>   #:use-module ((guix licenses) #:prefix license:)
>   #:use-module (guix packages)
>   #:use-module (guix download)
>   #:use-module (guix git-download)
>   #:use-module (guix utils)
>   #:use-module (guix build-system r)
>   #:use-module (gnu packages)
>   #:use-module (gnu packages statistics))
> 
> (define-public r-foofactors
>   (let ((commit "ef71e8d2e82fa80e0cfc249fd42f50c01924326d")
>         (revision "1"))
>     (package
>       (name "r-foofactors")
>       (version (git-version "0.0.0.9000" revision commit))
>       (source
>        (origin
>          (method git-fetch)
>          (uri (git-reference
>                (url "git@github.com:peterloleungyau/foofactors.git")
>                (commit commit)))
>          (file-name (git-file-name name version))
>          (sha256
>           (base32
>            "1hmfwac2zdl8x6r21yy5b257c4891106ana4j81hfn6rd0rl9f72"))))
>       (build-system r-build-system)
>       (propagated-inputs
>        `(("r-forcats" ,r-forcats)))
>       (home-page "https://github.com/jennybc/foofactors";)
>       (synopsis "A R package to make factors less aggravating.")
>       (description
>        "Factors have driven people to extreme measures, like ordering
> custom conference ribbons and laptop stickers to express how HELLNO
> we
> feel about stringsAsFactors. And yet, sometimes you need them. Can
> they
> be made less maddening? Let's find out.")
>       (license license:expat))))
> 
> 
> Note that I have cloned the original public repository to my private
> repository (for testing purpose). I have added the package definition
> to my local ~/to_keep/projects/my-guix-pkgs/my-packages/r-pkgs.scm
> 
> Then I test building it locally with
> 
> $ guix build -L ~/to_keep/projects/my-guix-pkgs/ r-foofactors
> The following derivations will be built:
>    /gnu/store/gnzw26jl9vw3z10cdnpcahd67zlf1ziy-r-foofactors-
> 0.0.0.9000-1.ef71e8d.drv
>    /gnu/store/2l35rb0s5fjk1v8vczir6cp6lfmbbf12-r-foofactors-
> 0.0.0.9000-1.ef71e8d-checkout.drv
> building /gnu/store/2l35rb0s5fjk1v8vczir6cp6lfmbbf12-r-foofactors-
> 0.0.0.9000-1.ef71e8d-checkout.drv...
> guile: warning: failed to install locale
> environment variable `PATH' set to
> `/gnu/store/378zjf2kgajcfd7mfr98jn5xyc5wa3qv-gzip-
> 1.10/bin:/gnu/store/sf3rbvb6iqcphgm1afbplcs72hsywg25-tar-1.32/bin'
> hint: Using 'master' as the name for the initial branch. This default
> branch name
> hint: is subject to change. To configure the initial branch name to
> use in all
> hint: of your new repositories, which will suppress this warning,
> call:
> hint:
> hint:   git config --global init.defaultBranch <name>
> hint:
> hint: Names commonly chosen instead of 'master' are 'main', 'trunk'
> and
> hint: 'development'. The just-created branch can be renamed via this
> command:
> hint:
> hint:   git branch -m <name>
> Initialized empty Git repository in
> /gnu/store/7i9py1b47lsg2d2wqjk68ha04rv2l89i-r-foofactors-0.0.0.9000-
> 1.ef71e8d-checkout/.git/
> error: cannot run ssh: No such file or directory
> fatal: unable to fork
> Failed to do a shallow fetch; retrying a full fetch...
> error: cannot run ssh: No such file or directory
> fatal: unable to fork
> git-fetch: '/gnu/store/ra24wp6glfzmpx1w6i3471aqcqqdrk96-git-minimal-
> 2.32.0/bin/git
> fetch origin' failed with exit code 128
> Trying content-addressed mirror at berlin.guix.gnu.org...
> Trying content-addressed mirror at berlin.guix.gnu.org...
> Trying to download from Software Heritage...
> builder for `/gnu/store/2l35rb0s5fjk1v8vczir6cp6lfmbbf12-r-
> foofactors-0.0.0.9000-1.ef71e8d-checkout.drv'
> failed to produce output path `/gnu/store/7i9py1b47lsg2d2wqjk68ha04r
> build of /gnu/store/2l35rb0s5fjk1v8vczir6cp6lfmbbf12-r-foofactors-
> 0.0.0.9000-1.ef71e8d-checkout.drv
> failed
> View build log at
> '/var/log/guix/drvs/2l/35rb0s5fjk1v8vczir6cp6lfmbbf12-r-foofactors-
> 0.0.0.9000-1.ef71e8d-checkout.drv.bz2'.
> cannot build derivation
> `/gnu/store/gnzw26jl9vw3z10cdnpcahd67zlf1ziy-r-foofactors-0.0.0.9000-
> 1.ef71e8d.drv':
> 1 dependencies couldn't be built
> guix build: error: build of
> `/gnu/store/gnzw26jl9vw3z10cdnpcahd67zlf1ziy-r-foofactors-0.0.0.9000-
> 1.ef71e8d.drv'
> failed
> 
> 
> Why is there an error of "cannot run ssh"? Is it that git-fetch does
> not support fetching over SSH?
Yes, git-fetch does not support fetching over SSH.  "Cannot run ssh" is
the error returned because the ssh program is missing at fetch time,
but even if it existed, you'd get a different error, namely one of
lacking keys.  You'd have to set up Guix to authenticate itself as you
for pulling the source and while that is in theory possible, there is a
potential security risk attached to most ways of solving it and no
clear path forward.

Furthermore, such a feature, were it integrated in Guix, is likely only
to be used for nonfree software and thus located closely to such
software itself.

> I would like to prompt the use of Guix for per-project management in
> my small team of data scientists, so we would need a private channel
> for a few internal R packages. The above problem is a real blocker.
> Any help is greatly appreciated.
I don't think this has to necessarily be a blocker.  You can point git-
fetch to file:// URIs, so your channel could have file:///path/to/repo
and it'd work under the assumption that your scientists run git pull on
those repos frequently enough (you could automate that with a script,
perhaps even one written in Guile/a handwritten Guix extension).  If
you have company/university intranet, you could also expose those
internal package over that on a well-known address, that's not
reachable from outside.

Regards,
Leo