machine: hetzner: Fix initial deploy when ssh-key is #f.

This fixes a regression introduced in commit a2ef2bcbfd7 ("machine: hetzner:
Allow connections using ssh-agent"), where having no ssh-key would cause the
early Hetzner provisioning to fail due to the lack of SSH authentication.

* gnu/machine/hetzner.scm (%hetzner-ssh-key-file): New parameter.
(<hetzner-configuration>) [ssh-public-key]: Compute default according to the
value of the private ssh-key field.  Introduce an indirection via...
(hetzner-configuration-ssh-public-key): ... this new procedure, to honor
%hetzner-ssh-key-file.
(hetzner-configuration-ssh-key): Likewise for the private ssh-key.
(hetzner-configuration-ssh-key-fingerprint): Rename to...
(public-key->fingerprint): ... this, taking just the public key as argument.
Update doc.
(hetzner-configuration-ssh-key-public): Rename to...
(public-key->string-with-type): ...this, for clarity, and accept just a
public-key object.  Update doc.
(hetzner-machine-ssh-key): Exit early with #f when no ssh key is provided.
(temporary-ssh-key-file): New procedure.
(hetzner-machine-ssh-key-create): Assert a public key is defined.  Adjust
calls to renamed procedures, and adjust for the `hetzner-api-server-create'
API change.
(hetzner-machine-enable-rescue-system): Refine doc and fix code path when
ssh-key is #f.
(hetzner-machine-rescue-install-os): Document.
(hetzner-machine-provision): Refine doc. Remove extraneous sleep and #:unwind
argument. Limit ssh-session dynamic scope to where it's needed.
(cleanup-temporary-ssh-key/maybe): New procedure.
(deploy-hetzner): Create and use a temporary SSH key when none is defined, and
clean it up when done or on errors.
* gnu/machine/hetzner/http.scm (hetzner-api-server-create): Make ssh-keys a
keyword argument, and fix execution when it's #f.
(hetzner-api-server-enable-rescue-system): Likewise.
* tests/machine/hetzner.scm ("deploy-machine-mock-with-unprovisioned-server"):
Adjust test.
* tests/machine/hetzner/http.scm (create-server)
("hetzner-api-server-create-unit")
("hetzner-api-server-enable-rescue-system-unit")
("hetzner-api-actions-integration")
("hetzner-api-server-enable-rescue-system-integration"): Likewise.
* doc/guix.texi (Invoking guix deploy): Precise what happens when 'ssh-key' is
 #f in hetzner-configuration, and suggest declaratively authorizing your SSH
key.

Change-Id: I812b348fb553f3b5aebd0bf66850c6ecb9e06653

1 files changed, 13 insertions, 1 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index b194dab4b89..14bcc5817b0 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -50346,6 +50346,8 @@ accepts store items it receives from the coordinator:
 # guix archive --authorize < coordinator-public-key.txt
 @end example
 
+@cindex @command{guix deploy, sudo configuration}
+@anchor{guix-deploy-via-sudo}
 @code{user}, in this example, specifies the name of the user account to log in
 as to perform the deployment.  Its default value is @code{root}, but root
 login over SSH may be forbidden in some cases.  To work around this,
@@ -50562,7 +50564,17 @@ small to bootstrap a Guix system from.
 
 @item @code{ssh-key} (default: @code{#f})
 If specified, the file name of the SSH private key to use to
-authenticate with the remote host.
+authenticate with the remote host.  If left unspecified, a temporary SSH
+key is used during the early provisioning of the machine, after which
+the authentication with the final machine is handled by your SSH client
+or agent.  It's a good idea to have your public SSH key authorized
+declaratively in the @code{operating-system} specification provided, via
+the @code{authorized-keys} field of the @code{openssh-configuration}
+record.  To be able to run @samp{guix deploy} after the initial
+provisioning is done, an SSH connection to the root account or a
+password-less sudo configuration is needed (@pxref{guix-deploy-via-sudo,
+Invoking guix deploy}).  For the later, you must also explicitly specify
+the @code{user} field, which otherwise defaults to @code{"root"}.
 
 @item @code{ssh-public-key} (default: extracted from @code{ssh-key})
 If specified, either a public key as returned by