From ed15dfcf31ec35c58f5a44d1d8adf5048da67ea6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Tue, 3 Dec 2019 21:59:09 +0100
Subject: [PATCH] machine: ssh: <machine-ssh-configuration> can include the
 host key.

* gnu/machine/ssh.scm (<machine-ssh-configuration>)[host-key]: New field.
(machine-ssh-session): Pass #:host-key to 'open-ssh-session'.
* doc/guix.texi (Invoking guix deploy): Document it.
---
 doc/guix.texi       | 12 ++++++++++++
 gnu/machine/ssh.scm |  9 +++++++--
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/doc/guix.texi b/doc/guix.texi
index c1ce5bc896..7d50f31d20 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -26447,6 +26447,18 @@ keyring.
 @item @code{identity} (default: @code{#f})
 If specified, the path to the SSH private key to use to authenticate with the
 remote host.
+
+@item @code{host-key} (default: @code{#f})
+This should be the SSH host key of the machine, which looks like this:
+
+@example
+ssh-ed25519 AAAAC3Nz@dots{} root@@example.org
+@end example
+
+When @code{host-key} is @code{#f}, the server is authenticated against
+the @file{~/.ssh/known_hosts} file, just like the OpenSSH @command{ssh}
+client does.
+
 @end table
 @end deftp
 
diff --git a/gnu/machine/ssh.scm b/gnu/machine/ssh.scm
index 6e3ed0e092..23ae917b79 100644
--- a/gnu/machine/ssh.scm
+++ b/gnu/machine/ssh.scm
@@ -54,6 +54,7 @@
             machine-ssh-configuration-authorize?
             machine-ssh-configuration-port
             machine-ssh-configuration-user
+            machine-ssh-configuration-host-key
             machine-ssh-configuration-session))
 
 ;;; Commentary:
@@ -87,6 +88,8 @@
   (identity       machine-ssh-configuration-identity       ; path to a private key
                   (default #f))
   (session        machine-ssh-configuration-session        ; session
+                  (default #f))
+  (host-key       machine-ssh-configuration-host-key       ; #f | string
                   (default #f)))
 
 (define (machine-ssh-session machine)
@@ -98,11 +101,13 @@ one from the configuration's parameters if one was not provided."
         (let ((host-name (machine-ssh-configuration-host-name config))
               (user (machine-ssh-configuration-user config))
               (port (machine-ssh-configuration-port config))
-              (identity (machine-ssh-configuration-identity config)))
+              (identity (machine-ssh-configuration-identity config))
+              (host-key (machine-ssh-configuration-host-key config)))
           (open-ssh-session host-name
                             #:user user
                             #:port port
-                            #:identity identity)))))
+                            #:identity identity
+                            #:host-key host-key)))))
 
 
 ;;;