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|
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2016 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
(define-module (gnu services herd)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-9)
#:use-module (srfi srfi-11)
#:use-module (srfi srfi-34)
#:use-module (srfi srfi-35)
#:use-module (ice-9 match)
#:export (%shepherd-socket-file
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
live-service?
live-service-provision
live-service-requirement
live-service-running
current-services
unload-services
unload-service
load-services
start-service
stop-service))
;;; Commentary:
;;;
;;; This module provides an interface to the GNU Shepherd, similar to the
;;; 'herd' command. Essentially it implements a subset of the (shepherd comm)
;;; module, but focusing only on the parts relevant to 'guix system
;;; reconfigure'.
;;;
;;; Code:
(define %shepherd-socket-file
(make-parameter "/var/run/shepherd/socket"))
(define* (open-connection #:optional (file (%shepherd-socket-file)))
"Open a connection to the daemon, using the Unix-domain socket at FILE, and
return the socket."
;; The protocol is sexp-based and UTF-8-encoded.
(with-fluids ((%default-port-encoding "UTF-8"))
(let ((sock (socket PF_UNIX SOCK_STREAM 0))
(address (make-socket-address PF_UNIX file)))
(catch 'system-error
(lambda ()
(connect sock address)
(setvbuf sock _IOFBF 1024)
sock)
(lambda args
(close-port sock)
(apply throw args))))))
(define-syntax-rule (with-shepherd connection body ...)
"Evaluate BODY... with CONNECTION bound to an open socket to PID 1."
(let ((connection (open-connection)))
body ...))
(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)
(raise (condition (&service-not-found-error
(service service)))))
(('error ('version 0 x ...) 'action-not-found action service)
(raise (condition (&action-not-found-error
(service service)
(action action)))))
(('error ('version 0 x ...) 'action-exception action service
key (args ...))
(raise (condition (&action-exception-error
(service service)
(action action)
(key key) (args args)))))
(('error . _)
(raise (condition (&unknown-shepherd-error (sexp error)))))
(#f ;not an error
#t)))
(define (display-message 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
result. Otherwise return #f."
(with-shepherd sock
(write `(shepherd-command (version 0)
(action ,action)
(service ,service)
(arguments ,arguments)
(directory ,(getcwd)))
sock)
(force-output sock)
(match (read sock)
(('reply ('version 0 _ ...) ('result result) ('error #f)
('messages messages))
(for-each display-message messages)
(cont result))
(('reply ('version 0 x ...) ('result y) ('error error)
('messages messages))
(for-each display-message messages)
(raise-shepherd-error error)
#f)
(x
;; invalid reply
#f))))
(define-syntax-rule (with-shepherd-action service (action args ...)
result body ...)
(invoke-action service action (list args ...)
(lambda (result) body ...)))
(define-syntax alist-let*
(syntax-rules ()
"Bind the given KEYs in EXP to the corresponding items in ALIST. ALIST
is assumed to be a list of two-element tuples rather than a traditional list
of pairs."
((_ alist (key ...) exp ...)
(let ((key (and=> (assoc-ref alist 'key) car)) ...)
exp ...))))
;; Information about live Shepherd services.
(define-record-type <live-service>
(live-service provision requirement running)
live-service?
(provision live-service-provision) ;list of symbols
(requirement live-service-requirement) ;list of symbols
(running live-service-running)) ;#f | object
(define (current-services)
"Return the list of currently defined Shepherd services, represented as
<live-service> objects. Return #f if the list of services could not be
obtained."
(with-shepherd-action 'root ('status) services
(match services
((('service ('version 0 _ ...) _ ...) ...)
(map (lambda (service)
(alist-let* service (provides requires running)
(live-service provides requires running)))
services))
(x
#f))))
(define (unload-service service)
"Unload SERVICE, a symbol name; return #t on success."
(with-shepherd-action 'root ('unload (symbol->string service)) result
result))
(define (%load-file file)
"Load FILE in the Shepherd."
(with-shepherd-action 'root ('load file) result
result))
(define (eval-there exp)
"Eval EXP in the Shepherd."
(with-shepherd-action 'root ('eval (object->string exp)) result
result))
(define (load-services files)
"Load and register the services from FILES, where FILES contain code that
returns a shepherd <service> object."
(eval-there `(register-services
,@(map (lambda (file)
`(primitive-load ,file))
files))))
(define (start-service name)
(with-shepherd-action name ('start) result
result))
(define (stop-service name)
(with-shepherd-action name ('stop) result
result))
;; Local Variables:
;; eval: (put 'alist-let* 'scheme-indent-function 2)
;; eval: (put 'with-shepherd 'scheme-indent-function 1)
;; eval: (put 'with-shepherd-action 'scheme-indent-function 3)
;; End:
;;; herd.scm ends here
|
