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services: herd: Move UI handling to 'guix system'. 

This makes (gnu services herd) independent of (guix ui).

* gnu/services/herd.scm (&shepherd-error, &service-not-found-error)
(&action-not-found-error, &action-exception-error)
(&unknown-shepherd-error): New error condition types.
(report-action-error): Remove.
(raise-shepherd-error): New procedure.
(display-message): Do not use 'info' and '_'.
(invoke-action): Use 'raise-shepherd-error' instead of
'report-action-error'.  Do not use 'warning'.
(current-services): Do not use 'warning'.
* guix/scripts/system.scm (with-shepherd-error-handling): New macro.
(report-shepherd-error, call-with-service-upgrade-info): New
procedures.
(upgrade-shepherd-services): Use it.
This commit is contained in:
Ludovic Courtès 2016-05-04 16:38:22 +02:00
parent af5640d1dd
commit 8bf92e3904
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GPG Key ID: 090B11993D9AEBB5
2 changed files with 151 additions and 67 deletions
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80
gnu/services/herd.scm
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@ -17,12 +17,27 @@
;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
(define-module (gnu services herd)
#:use-module (guix ui)
#:use-module (guix utils)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-11)
#:use-module (srfi srfi-34)
#:use-module (srfi srfi-35)
#:use-module (ice-9 match)
#:export (current-services
#:export (shepherd-error?
service-not-found-error?
service-not-found-error-service
action-not-found-error?
action-not-found-error-service
action-not-found-error-action
action-exception-error?
action-exception-error-service
action-exception-error-action
action-exception-error-key
action-exception-error-arguments
unknown-shepherd-error?
unknown-shepherd-error-sexp
current-services
unload-services
unload-service
load-services
@ -61,31 +76,54 @@ return the socket."
(let ((connection (open-connection)))
body ...))
(define (report-action-error error)
"Report ERROR, an sexp received by a shepherd client in reply to COMMAND, a
command object."
(define-condition-type &shepherd-error &error
shepherd-error?)
(define-condition-type &service-not-found-error &shepherd-error
service-not-found-error?
(service service-not-found-error-service))
(define-condition-type &action-not-found-error &shepherd-error
action-not-found-error?
(service action-not-found-error-service)
(action action-not-found-error-action))
(define-condition-type &action-exception-error &shepherd-error
action-exception-error?
(service action-exception-error-service)
(action action-exception-error-action)
(key action-exception-error-key)
(args action-exception-error-arguments))
(define-condition-type &unknown-shepherd-error &shepherd-error
unknown-shepherd-error?
(sexp unknown-shepherd-error-sexp))
(define (raise-shepherd-error error)
"Raise an error condition corresponding to ERROR, an sexp received by a
shepherd client in reply to COMMAND, a command object. Return #t if ERROR
does not denote an error."
(match error
(('error ('version 0 x ...) 'service-not-found service)
(report-error (_ "service '~a' could not be found~%")
service))
(raise (condition (&service-not-found-error
(service service)))))
(('error ('version 0 x ...) 'action-not-found action service)
(report-error (_ "service '~a' does not have an action '~a'~%")
service action))
(raise (condition (&action-not-found-error
(service service)
(action action)))))
(('error ('version 0 x ...) 'action-exception action service
key (args ...))
(report-error (_ "exception caught while executing '~a' \
on service '~a':~%")
action service)
(print-exception (current-error-port) #f key args))
(raise (condition (&action-exception-error
(service service)
(action action)
(key key) (args args)))))
(('error . _)
(report-error (_ "something went wrong: ~s~%")
error))
(raise (condition (&unknown-shepherd-error (sexp error)))))
(#f ;not an error
#t)))
(define (display-message message)
;; TRANSLATORS: Nothing to translate here.
(info (_ "shepherd: ~a~%") message))
(format (current-error-port) "shepherd: ~a~%" message))
(define* (invoke-action service action arguments cont)
"Invoke ACTION on SERVICE with ARGUMENTS. On success, call CONT with the
@ -107,10 +145,10 @@ result. Otherwise return #f."
(('reply ('version 0 x ...) ('result y) ('error error)
('messages messages))
(for-each display-message messages)
(report-action-error error)
(raise-shepherd-error error)
#f)
(x
(warning (_ "invalid shepherd reply~%"))
;; invalid reply
#f))))
(define-syntax-rule (with-shepherd-action service (action args ...)
@ -129,7 +167,8 @@ of pairs."
(define (current-services)
"Return two lists: the list of currently running services, and the list of
currently stopped services."
currently stopped services. Return #f and #f if the list of services could
not be obtained."
(with-shepherd-action 'root ('status) services
(match services
((('service ('version 0 _ ...) _ ...) ...)
@ -144,7 +183,6 @@ currently stopped services."
'()
services))
(x
(warning (_ "failed to obtain list of shepherd services~%"))
(values #f #f)))))
(define (unload-service service)

84
guix/scripts/system.scm
View File

@ -236,37 +236,59 @@ BODY..., and restore them."
(with-monad %store-monad
(return #f)))))
(define (upgrade-shepherd-services os)
"Upgrade the Shepherd (PID 1) by unloading obsolete services and loading new
services specified in OS and not currently running.
(define-syntax-rule (with-shepherd-error-handling body ...)
(warn-on-system-error
(guard (c ((shepherd-error? c)
(report-shepherd-error c)))
body ...)))
This is currently very conservative in that it does not stop or unload any
running service. Unloading or stopping the wrong service ('udev', say) could
bring the system down."
(define (report-shepherd-error error)
"Report ERROR, a '&shepherd-error' error condition object."
(cond ((service-not-found-error? error)
(report-error (_ "service '~a' could not be found~%")
(service-not-found-error-service error)))
((action-not-found-error? error)
(report-error (_ "service '~a' does not have an action '~a'~%")
(action-not-found-error-service error)
(action-not-found-error-action error)))
((action-exception-error? error)
(report-error (_ "exception caught while executing '~a' \
on service '~a':~%")
(action-exception-error-action error)
(action-exception-error-service error))
(print-exception (current-error-port) #f
(action-exception-error-key error)
(action-exception-error-arguments error)))
((unknown-shepherd-error? error)
(report-error (_ "something went wrong: ~s~%")
(unknown-shepherd-error-sexp error)))
((shepherd-error? error)
(report-error (_ "shepherd error~%")))
((not error) ;not an error
#t)))
(define (call-with-service-upgrade-info new-services mproc)
"Call MPROC, a monadic procedure in %STORE-MONAD, passing it the list of
names of services to load (upgrade), and the list of names of services to
unload."
(define (essential? service)
(memq service '(root shepherd)))
(define new-services
(service-parameters
(fold-services (operating-system-services os)
#:target-type shepherd-root-service-type)))
(define new-service-names
(map (compose first shepherd-service-provision)
new-services))
;; Arrange to simply emit a warning if we cannot connect to the shepherd.
(warn-on-system-error
(let-values (((running stopped) (current-services)))
(define to-load
(if (and running stopped)
(let* ((to-load
;; Only load services that are either new or currently stopped.
(remove (lambda (service)
(memq (first (shepherd-service-provision service))
running))
new-services))
(define to-unload
;; Unload services that are (1) no longer required, or (2) are in
;; TO-LOAD.
(to-unload
;; Unload services that are (1) no longer required, or (2) are
;; in TO-LOAD.
(remove essential?
(append (remove (lambda (service)
(memq service new-service-names))
@ -274,8 +296,28 @@ bring the system down."
(filter (lambda (service)
(memq service stopped))
(map shepherd-service-canonical-name
to-load)))))
to-load))))))
(mproc to-load to-unload))
(with-monad %store-monad
(warning (_ "failed to obtain list of shepherd services~%"))
(return #f)))))
(define (upgrade-shepherd-services os)
"Upgrade the Shepherd (PID 1) by unloading obsolete services and loading new
services specified in OS and not currently running.
This is currently very conservative in that it does not stop or unload any
running service. Unloading or stopping the wrong service ('udev', say) could
bring the system down."
(define new-services
(service-parameters
(fold-services (operating-system-services os)
#:target-type shepherd-root-service-type)))
;; Arrange to simply emit a warning if the service upgrade fails.
(with-shepherd-error-handling
(call-with-service-upgrade-info new-services
(lambda (to-load to-unload)
(for-each (lambda (unload)
(info (_ "unloading service '~a'...~%") unload)
(unload-service unload))
@ -295,7 +337,7 @@ bring the system down."
(for-each start-service
(map shepherd-service-canonical-name to-start))
(return #t))))))))
(return #t)))))))))
(define* (switch-to-system os
#:optional (profile %system-profile))
@ -839,4 +881,8 @@ argument list and OPTS is the option alist."
(parameterize ((%graft? (assoc-ref opts 'graft?)))
(process-command command args opts)))))
;;; Local Variables:
;;; eval: (put 'call-with-service-upgrade-info 'scheme-indent-function 1)
;;; End:
;;; system.scm ends here