Subject: bug#71144: Interactive prompt opened upon shepherd config file error

From: Ludovic Courtès <[email-masked]>
Date: Sat, 25 May 2024 11:11:04 +0200

Ludovic Courtès <[email-masked]> skribis:

> I think we should change the above to log and gracefully handle failure
> to load an individual service file.

With the change below, every service except the offending one is loaded
and started as expected:

--8<---------------cut here---------------start------------->8---
[   22.450515] shepherd[1]: Service root running with value #t.
[   22.454624] shepherd[1]: Service root has been started.
[   22.711738] shepherd[1]: Exception caught while loading '/gnu/store/fjis6iqpjfcnr90fy8rsg9v4j828jslv-shepherd-gwl-web.go': #<&compound-exception components: (#<&undefined-variable> #<&origin origin: #f> #<&message message: "Unbound variable: ~S"> #<&irritants irri
[   22.711839] tants: (make-forkexec-constructor/container)> #<&exception-with-kind-and-args kind: unbound-variable args: (#f "Unbound variable: ~S" (make-forkexec-constructor/container) #f)>)>
[   22.755146] shepherd[1]: starting services...
[   22.756491] shepherd[1]: Configuration successfully loaded from '/gnu/store/mq7y31xnjcjwjkyf6w7qiaq61g6n9f5x-shepherd.conf'.
Uncaught exception in task:
In fibers.scm:
    172:8  7 (_)
In ice-9/exceptions.scm:
   406:15  6 (_)
In ice-9/boot-9.scm:
  1752:10  5 (with-exception-handler _ _ #:unwind? _ # _)
In shepherd/service.scm:
   824:39  4 (_)
In oop/goops.scm:
  1567:11  3 (cache-miss #f)
   1585:2  2 (_ _ _)
In ice-9/boot-9.scm:
  1685:16  1 (raise-exception _ #:continuable? _)
  1683:16  0 (raise-exception _ #:continuable? _)
ice-9/boot-9.scm:1683:16: In procedure raise-exception:
No applicable method for #<<generic> one-shot-service? (1)> in call (one-shot-service? #f)
[   22.798737] shepherd[1]: Starting service user-file-systems...
[   22.800361] shepherd[1]: Starting service root-file-system...
[   22.802015] shepherd[1]: Starting service host-name...
[   22.803688] shepherd[1]: Starting service pam...
[   22.805372] shepherd[1]: Starting service sysctl...
[   22.806926] shepherd[1]: Starting service loopback...
[   22.808225] shepherd[1]: Starting service firewall...
--8<---------------cut here---------------end--------------->8---

(There’s still this scary-looking but harmless backtrace in the middle:
that’s because (start-in-the-background '(something-that-does-not-exist))
throws like that as of 0.10.4.)

Once booted, shepherd is fine and you can interact normally with it; the
only thing missing is, in this case, the ‘gwl-web’ service, which we
failed to load.

I think that’s a significant improvement.

Thoughts?

Ludo’.

diff --git a/gnu/services/shepherd.scm b/gnu/services/shepherd.scm
index 455e972535d..f13c52c37ba 100644
--- a/gnu/services/shepherd.scm
+++ b/gnu/services/shepherd.scm
@@ -380,8 +380,7 @@ (define (shepherd-configuration-file services shepherd)
         (scm->go (cute scm->go <> shepherd)))
     (define config
       #~(begin
-          (use-modules (srfi srfi-34)
-                       (system repl error-handling))
+          (use-modules (srfi srfi-1))
 
           (define (make-user-module)
             ;; Copied from (shepherd support), where it's private.
@@ -417,17 +416,22 @@ (define (shepherd-configuration-file services shepherd)
 
           ;; Arrange to spawn a REPL if something goes wrong.  This is better
           ;; than a kernel panic.
-          (call-with-error-handling
-            (lambda ()
-              (register-services
-               (parameterize ((current-warning-port
-                               (%make-void-port "w")))
-                 (map (lambda (file)
-                        (save-module-excursion
-                         (lambda ()
-                           (set-current-module (make-user-module))
-                           (load-compiled file))))
-                      '#$(map scm->go files))))))
+          (register-services
+           (parameterize ((current-warning-port (%make-void-port "w")))
+             (filter-map (lambda (file)
+                           (with-exception-handler
+                               (lambda (exception)
+                                 (format #t "Exception caught \
+while loading '~a': ~s~%"
+                                         file exception)
+                                 #f)
+                             (lambda ()
+                               (save-module-excursion
+                                (lambda ()
+                                  (set-current-module (make-user-module))
+                                  (load-compiled file))))
+                             #:unwind? #t))
+                         '#$(map scm->go files))))
 
           (format #t "starting services...~%")
           (let ((services-to-start