bug#38320: Cuirass: Allow to use authenticated Git repositories as inputs

[Mathieu Othacehe <m.othacehe@gmail.com>]

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Hello,

Here's a small patch to (guix git) so that cloning/fetching from ssh
authenticated repositories is supported using ssh agent.

I tested:

* guix pull --url=git@gitlab.com:mothacehe/private.git
* guix pull with the following channel configuration

--8<---------------cut here---------------start------------->8---
(cons* (channel
        (name 'gitlab)
        (url "git@gitlab.com:mothacehe/test-channel.git"))
       %default-channels)
--8<---------------cut here---------------end--------------->8---

This works fine, but we still need to see how it works for Cuirass
inputs and (guix git-download) module.

Mathieu

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From ae380c15f1c37e2c94e0954975f5f712e76340ac Mon Sep 17 00:00:00 2001
From: Mathieu Othacehe <m.othacehe@gmail.com>
Date: Mon, 3 Feb 2020 18:05:02 +0100
Subject: [PATCH] git: Add ssh authentication support.

SSH agent authentication method is used.

* guix/git.scm (auth-method): New variable,
(clone*): pass previous variable in clone options,
(update-cached-checkout): pass previous variable in fetch options.
---
 guix/git.scm | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/guix/git.scm b/guix/git.scm
index a12f1eec8e..aee7b325e0 100644
--- a/guix/git.scm
+++ b/guix/git.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
+;;; Copyright © 2017, 2020 Mathieu Othacehe <m.othacehe@gmail.com>
 ;;; Copyright © 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
@@ -108,6 +108,9 @@ the 'SSL_CERT_FILE' and 'SSL_CERT_DIR' environment variables."
                               (string-append "R:" url)
                               url))))))
 
+;; Default authentication method.
+(define auth-method (%make-auth-ssh-agent))
+
 (define (clone* url directory)
   "Clone git repository at URL into DIRECTORY.  Upon failure,
 make sure no empty directory is left behind."
@@ -119,7 +122,9 @@ make sure no empty directory is left behind."
       ;; value in Guile-Git: <https://bugs.gnu.org/29238>.
       (if (module-defined? (resolve-interface '(git))
                            'clone-init-options)
-          (clone url directory (clone-init-options))
+          (clone url directory
+                 (make-clone-options
+                  #:fetch-options (make-fetch-options auth-method)))
           (clone url directory)))
     (lambda _
       (false-if-exception (rmdir directory)))))
@@ -281,7 +286,8 @@ When RECURSIVE? is true, check out submodules as well, if any."
      ;; Only fetch remote if it has not been cloned just before.
      (when (and cache-exists?
                 (not (reference-available? repository ref)))
-       (remote-fetch (remote-lookup repository "origin")))
+       (remote-fetch (remote-lookup repository "origin")
+                     #:fetch-options (make-fetch-options auth-method)))
      (when recursive?
        (update-submodules repository #:log-port log-port))
      (let ((oid (switch-to-ref repository canonical-ref)))
-- 
2.25.0


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Ludovic Courtès writes:

> Hey ho!
>
> Clément Lassieur <clement@lassieur.org> skribis:
>
>> Whoo, nice, thank you so much Mathieu!  I'll test everything this
>> week-end probably, and start working on the (guix git) / Cuirass
>> counterpart (which is 1% of the work :D).
>
> Neat!
>
>>> So "latest-repository-commit" could be call with ssh authentication
>>> parameters. However, the guix-daemon won't be able to communicate with the
>>> user ssh-agent, and storing an unencrypted private ssh key in the store
>>> doesn't feel great to me.
>>>
>>> Do you see any workaround?
>>
>> As far as I understand, LATEST-REPOSITORY-COMMIT is never called by the
>> daemon, it downloads stuff first and then calls ADD-TO-STORE.  So both
>> using the SSH agent or passing a private SSH key should be
>> straightforward.
>
> Indeed.  ‘guix pull --url’ and ‘guix build --with-git-url’ (and similar)
> should work just fine.
>
> Thanks!
>
> Ludo’.