services: caddy: Expose configuration interfaces for shepherd service.

* modules/rosenthal/services/web.scm (caddy-configuration)
[shepherd-provision, shepherd-requirement, auto-start?]: New fields.
* modules/rosenthal/services/web.scm (caddy-shepherd-services): Use them.

modules/rosenthal/services/web.scm

@@ -51,6 +51,16 @@
    "")
   (caddyfile
    file-like
+   "")
+  ;; Shepherd
+  (shepherd-provision
+   (list-of-symbols '(caddy))
+   "")
+  (shepherd-requirement
+   (list-of-symbols '())
+   "")
+  (auto-start?
+   (boolean #t)
    ""))
 
 (define (caddy-accounts config)
@@ -91,10 +101,12 @@
                (chown file (passwd:uid user) (passwd:gid user)))
              (find-files data-dir #:directories? #t)))))))
 
-(define (caddy-shepherd-services config)
+(define caddy-shepherd-services
+  (match-record-lambda <caddy-configuration>
+      (shepherd-provision shepherd-requirement auto-start?)
     (list (shepherd-service
-          (provision '(caddy))
+            (provision shepherd-provision)
-          (requirement '(user-processes loopback))
+            (requirement `(user-processes loopback ,@shepherd-requirement))
             (start
              #~(make-forkexec-constructor
                 (list "/run/privileged/bin/caddy" "run"
@@ -106,7 +118,8 @@
                 #:resource-limits '((nofile 1048576 1048576))
                 #:environment-variables '("HOME=/var/lib/caddy")))
             (stop
-           #~(make-kill-destructor)))))
+             #~(make-kill-destructor))
+            (auto-start? auto-start?)))))
 
 (define caddy-service-type
   (service-type