services: udev: Use a fixed location for the rules directory and config.

Fixes <https://issues.guix.gnu.org/47681>.

This change adjusts the location of the udev configuration file and rules
directory to a fixed location.  Since udev relies on inotify to discover
change to its rules directory (/etc/udev/rules.d), by using a fixed directory
layout, new udev rules can be automatically picked up without restarting the
service.

* gnu/services/base.scm (udev-rules-union): Build rules output directly
in #$output.
(udev-shepherd-service)[start]: Adjust the UDEV_CONFIG_FILE and
EUDEV_RULES_DIRECTORY environment variables.
[actions]: Remove field.  The 'rules' action is no longer useful.
(udev.conf): New variable.
(udev-etc): New procedure.
(udev-service-type): Extend the etc-service-type with it.
This commit is contained in:
Maxim Cournoyer 2022-02-01 00:32:50 -05:00
parent 82d19441b9
commit e9fa17eb98
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@ -15,7 +15,7 @@
;;; Copyright © 2020, 2021 Brice Waegeneire <brice@waegenei.re>
;;; Copyright © 2021 qblade <qblade@protonmail.com>
;;; Copyright © 2021 Hui Lu <luhuins@163.com>
;;; Copyright © 2021 Maxim Cournoyer <maxim.cournoyer@gmail.com>
;;; Copyright © 2021, 2022 Maxim Cournoyer <maxim.cournoyer@gmail.com>
;;; Copyright © 2022 Guillaume Le Vaillant <glv@posteo.net>
;;;
;;; This file is part of GNU Guix.
@ -1995,8 +1995,7 @@ (define (rules-sub-directory directory)
(find directory-exists?
(map (cut string-append directory <>) %standard-locations)))
(mkdir-p (string-append #$output "/lib/udev"))
(union-build (string-append #$output "/lib/udev/rules.d")
(union-build #$output
(filter-map rules-sub-directory '#$packages)))))
(computed-file "udev-rules" build))
@ -2045,116 +2044,115 @@ (define kvm-udev-rule
(define udev-shepherd-service
;; Return a <shepherd-service> for UDEV with RULES.
(match-lambda
(($ <udev-configuration> udev)
(list
(shepherd-service
(provision '(udev))
;; Udev needs /dev to be a 'devtmpfs' mount so that new device nodes can
;; be added: see
;; <http://www.linuxfromscratch.org/lfs/view/development/chapter07/udev.html>.
(requirement '(root-file-system))
(documentation "Populate the /dev directory, dynamically.")
(start
(with-imported-modules (source-module-closure
'((gnu build linux-boot)))
#~(lambda ()
(define udevd
;; 'udevd' from eudev.
#$(file-append udev "/sbin/udevd"))
(define (wait-for-udevd)
;; Wait until someone's listening on udevd's control
;; socket.
(let ((sock (socket AF_UNIX SOCK_SEQPACKET 0)))
(let try ()
(catch 'system-error
(lambda ()
(connect sock PF_UNIX "/run/udev/control")
(close-port sock))
(lambda args
(format #t "waiting for udevd...~%")
(usleep 500000)
(try))))))
;; Allow udev to find the modules.
(setenv "LINUX_MODULE_DIRECTORY"
"/run/booted-system/kernel/lib/modules")
(let* ((kernel-release
(utsname:release (uname)))
(linux-module-directory
(getenv "LINUX_MODULE_DIRECTORY"))
(directory
(string-append linux-module-directory "/"
kernel-release))
(old-umask (umask #o022)))
;; If we're in a container, DIRECTORY might not exist,
;; for instance because the host runs a different
;; kernel. In that case, skip it; we'll just miss a few
;; nodes like /dev/fuse.
(when (file-exists? directory)
(make-static-device-nodes directory))
(umask old-umask))
(let ((pid (fork+exec-command
(list udevd)
#:environment-variables
(cons*
;; The first one is for udev, the second one for
;; eudev.
"UDEV_CONFIG_FILE=/etc/udev/udev.conf"
"EUDEV_RULES_DIRECTORY=/etc/udev/rules.d"
(string-append "LINUX_MODULE_DIRECTORY="
(getenv "LINUX_MODULE_DIRECTORY"))
(default-environment-variables)))))
;; Wait until udevd is up and running. This appears to
;; be needed so that the events triggered below are
;; actually handled.
(wait-for-udevd)
;; Trigger device node creation.
(system* #$(file-append udev "/bin/udevadm")
"trigger" "--action=add")
;; Wait for things to settle down.
(system* #$(file-append udev "/bin/udevadm")
"settle")
pid))))
(stop #~(make-kill-destructor))
;; When halting the system, 'udev' is actually killed by
;; 'user-processes', i.e., before its own 'stop' method was called.
;; Thus, make sure it is not respawned.
(respawn? #f)
;; We need additional modules.
(modules `((gnu build linux-boot) ;'make-static-device-nodes'
,@%default-modules)))))))
(define udev.conf
(computed-file "udev.conf"
#~(call-with-output-file #$output
(lambda (port)
(format port "udev_rules=\"/etc/udev/rules.d\"~%")))))
(define udev-etc
(match-lambda
(($ <udev-configuration> udev rules)
(let* ((rules (udev-rules-union (cons* udev kvm-udev-rule rules)))
(udev.conf (computed-file "udev.conf"
#~(call-with-output-file #$output
(lambda (port)
(format port
"udev_rules=\"~a/lib/udev/rules.d\"\n"
#$rules))))))
(list
(shepherd-service
(provision '(udev))
;; Udev needs /dev to be a 'devtmpfs' mount so that new device nodes can
;; be added: see
;; <http://www.linuxfromscratch.org/lfs/view/development/chapter07/udev.html>.
(requirement '(root-file-system))
(documentation "Populate the /dev directory, dynamically.")
(start
(with-imported-modules (source-module-closure
'((gnu build linux-boot)))
#~(lambda ()
(define udevd
;; 'udevd' from eudev.
#$(file-append udev "/sbin/udevd"))
(define (wait-for-udevd)
;; Wait until someone's listening on udevd's control
;; socket.
(let ((sock (socket AF_UNIX SOCK_SEQPACKET 0)))
(let try ()
(catch 'system-error
(lambda ()
(connect sock PF_UNIX "/run/udev/control")
(close-port sock))
(lambda args
(format #t "waiting for udevd...~%")
(usleep 500000)
(try))))))
;; Allow udev to find the modules.
(setenv "LINUX_MODULE_DIRECTORY"
"/run/booted-system/kernel/lib/modules")
(let* ((kernel-release
(utsname:release (uname)))
(linux-module-directory
(getenv "LINUX_MODULE_DIRECTORY"))
(directory
(string-append linux-module-directory "/"
kernel-release))
(old-umask (umask #o022)))
;; If we're in a container, DIRECTORY might not exist,
;; for instance because the host runs a different
;; kernel. In that case, skip it; we'll just miss a few
;; nodes like /dev/fuse.
(when (file-exists? directory)
(make-static-device-nodes directory))
(umask old-umask))
(let ((pid (fork+exec-command (list udevd)
#:environment-variables
(cons*
;; The first one is for udev, the second one for
;; eudev.
(string-append "UDEV_CONFIG_FILE=" #$udev.conf)
(string-append "EUDEV_RULES_DIRECTORY="
#$(file-append
rules "/lib/udev/rules.d"))
(string-append "LINUX_MODULE_DIRECTORY="
(getenv "LINUX_MODULE_DIRECTORY"))
(default-environment-variables)))))
;; Wait until udevd is up and running. This appears to
;; be needed so that the events triggered below are
;; actually handled.
(wait-for-udevd)
;; Trigger device node creation.
(system* #$(file-append udev "/bin/udevadm")
"trigger" "--action=add")
;; Wait for things to settle down.
(system* #$(file-append udev "/bin/udevadm")
"settle")
pid))))
(stop #~(make-kill-destructor))
;; When halting the system, 'udev' is actually killed by
;; 'user-processes', i.e., before its own 'stop' method was called.
;; Thus, make sure it is not respawned.
(respawn? #f)
;; We need additional modules.
(modules `((gnu build linux-boot) ;'make-static-device-nodes'
,@%default-modules))
(actions (list (shepherd-action
(name 'rules)
(documentation "Display the directory containing
the udev rules in use.")
(procedure #~(lambda (_)
(display #$rules)
(newline))))))))))))
`(("udev"
,(file-union
"udev" `(("udev.conf" ,udev.conf)
("rules.d" ,(udev-rules-union (cons* udev kvm-udev-rule
rules))))))))))
(define udev-service-type
(service-type (name 'udev)
(extensions
(list (service-extension shepherd-root-service-type
udev-shepherd-service)))
udev-shepherd-service)
(service-extension etc-service-type udev-etc)))
(compose concatenate) ;concatenate the list of rules
(extend (lambda (config rules)
(match config