services: base: Add file->udev-rule function.

This function allows passing a file-like object to the udev service.

* gnu/services/base.scm (file->udev-rule): New function.
* doc/guix.texi (Base Services): Document it.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>
This commit is contained in:
Maxim Cournoyer 2017-09-27 21:33:25 -04:00 committed by Ludovic Courtès
parent 2f05dd6b4c
commit 6e644cfdb3
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2 changed files with 115 additions and 21 deletions

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@ -9790,35 +9790,112 @@ Return a service that runs the Guix build daemon according to
@var{config}.
@end deffn
@cindex udev-service
@cindex udev-rule
@deffn {Scheme Procedure} udev-service [#:udev @var{udev}] [#:rules @var{'()}]
@deffn {Scheme Procedure} udev-service [#:udev @var{eudev} #:rules @code{'()}]
Run @var{udev}, which populates the @file{/dev} directory dynamically.
Additional udev rules can be provided as a list of files through the
@var{rules} variable. The procedure @var{udev-rule} simplifies the
creation of these rule files.
udev rules can be provided as a list of files through the @var{rules}
variable. The procedures @var{udev-rule} and @var{file->udev-rule} from
@code{(gnu services base)} simplify the creation of such rule files.
@deffn {Scheme Procedure} udev-rule [@var{file-name} @var{contents}]
Return a udev-rule file named @var{file-name} containing the rules
defined by the @var{contents} literal.
In the following example, a rule for a USB device is defined to be
stored in the file @file{90-usb-thing.rules}, and the default
@var{udev-service} is extended with it. The rule runs a script upon
detecting a USB device with a given product identifier.
stored in the file @file{90-usb-thing.rules}. The rule runs a script
upon detecting a USB device with a given product identifier.
@example
(define %example-udev-rule
(udev-rule "90-usb-thing.rules"
"ACTION==\"add\", SUBSYSTEM==\"usb\", ATTR@{product@}==\"Example\", RUN+=\"/path/to/script\""))
(operating-system
;; @dots{}
(services (modify-services %desktop-services
(udev-service-type config =>
(udev-configuration (inherit config)
(rules (append (udev-configuration-rules config)
(list %example-udev-rule))))))))
(udev-rule
"90-usb-thing.rules"
(string-append "ACTION==\"add\", SUBSYSTEM==\"usb\", "
"ATTR@{product@}==\"Example\", "
"RUN+=\"/path/to/script\"")))
@end example
@end deffn
@deffn {Scheme Procedure} urandom-seed-service @var{#f}
Here we show how the default @var{udev-service} can be extended with it.
@example
(operating-system
;; @dots{}
(services
(modify-services %desktop-services
(udev-service-type config =>
(udev-configuration (inherit config)
(rules (append (udev-configuration-rules config)
(list %example-udev-rule))))))))
@end example
@deffn {Scheme Procedure} file->udev-rule [@var{file-name} @var{file}]
Return a udev file named @var{file-name} containing the rules defined
within @var{file}, a file-like object.
The following example showcases how we can use an existing rule file.
@example
(use-modules (guix download) ;for url-fetch
(guix packages) ;for origin
;; @dots{})
(define %android-udev-rules
(file->udev-rule
"51-android-udev.rules"
(let ((version "20170910"))
(origin
(method url-fetch)
(uri (string-append "https://raw.githubusercontent.com/M0Rf30/"
"android-udev-rules/" version "/51-android.rules"))
(sha256
(base32 "0lmmagpyb6xsq6zcr2w1cyx9qmjqmajkvrdbhjx32gqf1d9is003"))))))
@end example
@end deffn
Additionally, Guix package definitions can be included in @var{rules} in
order to extend the udev rules with the definitions found under their
@file{lib/udev/rules.d} sub-directory. In lieu of the previous
@var{file->udev-rule} example, we could have used the
@var{android-udev-rules} package which exists in Guix in the @code{(gnu
packages android)} module.
The following example shows how to use the @var{android-udev-rules}
package so that the Android tool @command{adb} can detect devices
without root privileges. It also details how to create the
@code{adbusers} group, which is required for the proper functioning of
the rules defined within the @var{android-udev-rules} package. To
create such a group, we must define it both as part of the
@var{supplementary-groups} of our @var{user-account} declaration, as
well as in the @var{groups} field of the @var{operating-system} record.
@example
(use-modules (gnu packages android) ;for android-udev-rules
(gnu system shadow) ;for user-group
;; @dots{})
(operating-system
;; @dots{}
(users (cons (user-acount
;; @dots{}
(supplementary-groups
'("adbusers" ;for adb
"wheel" "netdev" "audio" "video"))
;; @dots{})))
(groups (cons (user-group (system? #t) (name "adbusers"))
%base-groups))
;; @dots{}
(services
(modify-services %desktop-services
(udev-service-type config =>
(udev-configuration (inherit config)
(rules (cons* android-udev-rules
(udev-configuration-rules config))))))))
@end example
@end deffn
@deffn {Scheme Procedure} urandom-seed-service
Save some entropy in @var{%random-seed-file} to seed @file{/dev/urandom}
when rebooting.
@end deffn
@ -9930,7 +10007,7 @@ to add @var{device} to the kernel's entropy pool. The service will fail if
@cindex session limits
@cindex ulimit
@cindex priority
@deffn {Scheme Procedure} pam-limits-service [#:limits @var{limits}]
@deffn {Scheme Procedure} pam-limits-service [#:limits @code{'()}]
Return a service that installs a configuration file for the
@uref{http://linux-pam.org/Linux-PAM-html/sag-pam_limits.html,

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@ -71,6 +71,7 @@
udev-service-type
udev-service
udev-rule
file->udev-rule
login-configuration
login-configuration?
@ -1630,6 +1631,22 @@ item of @var{packages}."
(lambda (port)
(display #$contents port)))))))
(define (file->udev-rule file-name file)
"Return a directory with a udev rule file FILE-NAME which is a copy of FILE."
(computed-file file-name
(with-imported-modules '((guix build utils))
#~(begin
(use-modules (guix build utils))
(define rules.d
(string-append #$output "/lib/udev/rules.d"))
(define file-copy-dest
(string-append rules.d "/" #$file-name))
(mkdir-p rules.d)
(copy-file #$file file-copy-dest)))))
(define kvm-udev-rule
;; Return a directory with a udev rule that changes the group of /dev/kvm to
;; "kvm" and makes it #o660. Apparently QEMU-KVM used to ship this rule,