services: openssh: Start as an inetd service.

* gnu/services/ssh.scm (openssh-shepherd-service): Use
'make-inetd-constructor' when it is defined.
(<openssh-configuration>)[max-connections]: New field.
* gnu/tests/ssh.scm (run-ssh-test)["sshd PID"]: Adjust to cope with
PID-FILE being #f.
* gnu/tests/ssh.scm (%test-openssh): Pass #f as the 'pid-file'
argument.
* doc/guix.texi (Networking Services): Document 'max-connections'.

1 files changed, 17 insertions, 15 deletions

diff --git a/gnu/tests/ssh.scm b/gnu/tests/ssh.scm
index 791ff7b73f..e3dd601603 100644
--- a/gnu/tests/ssh.scm
+++ b/gnu/tests/ssh.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2016, 2017, 2018, 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2016-2022 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2017, 2018 Clément Lassieur <clement@lassieur.org>
 ;;; Copyright © 2017 Marius Bakke <mbakke@fastmail.com>
 ;;;
@@ -120,19 +120,21 @@ root with an empty password."
                marionette))
 
             ;; Check sshd's PID file.
-            (test-equal "sshd PID"
-              (wait-for-file #$pid-file marionette)
-              (marionette-eval
-               '(begin
-                  (use-modules (gnu services herd)
-                               (srfi srfi-1))
-
-                  (live-service-running
-                   (find (lambda (live)
-                           (memq 'ssh-daemon
-                                 (live-service-provision live)))
-                         (current-services))))
-               marionette))
+            (test-assert "sshd PID"
+              (let ((pid (marionette-eval
+                          '(begin
+                             (use-modules (gnu services herd)
+                                          (srfi srfi-1))
+
+                             (live-service-running
+                              (find (lambda (live)
+                                      (memq 'ssh-daemon
+                                            (live-service-provision live)))
+                                    (current-services))))
+                          marionette)))
+                (if #$pid-file
+                    (= pid (wait-for-file #$pid-file marionette))
+                    pid)))
 
             (test-assert "wait for port 22"
               (wait-for-tcp-port 22 marionette))
@@ -222,7 +224,7 @@ root with an empty password."
                                  (openssh-configuration
                                   (permit-root-login #t)
                                   (allow-empty-passwords? #t)))
-                        "/var/run/sshd.pid"
+                        #f                        ;inetd-style, no PID file
                         #:sftp? #t))))
 
 (define %test-dropbear