[bug#64471] [PATCH 0/2] File database update services

[bug#64471] [PATCH 0/2] File database update services

[Ludovic Courtès]

Hi!

These patches add two system services to periodically update file
databases: one for 'updatedb', and one for 'guix locate --update'.

I did not add them to '%base-services' mainly because: (1) 'updatedb'
builds a database of all the files available on the system, which
can be a problem on multi-user systems, and (2) the 'guix locate'
service is quite expensive ('time-machine' + 'store' method by
default) and eventually users may often download a pre-built database
from ci.guix or similar.

Thoughts?

Ludo'.

Ludovic Courtès (2):
  services: Add 'file-database' service.
  services: Add 'package-database' service.

 doc/guix.texi          | 111 ++++++++++++++++++++++++++++++++++++++-
 gnu/services/admin.scm | 116 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 226 insertions(+), 1 deletion(-)


base-commit: c4a836f65d178786a5dd1f7c2d9491bb2c7482b3
-- 
2.40.1

[bug#64471] [PATCH 1/2] services: Add 'file-database' service.

[Ludovic Courtès]

* gnu/services/admin.scm (%default-file-database-update-schedule)
(%default-file-database-excluded-directories): New variables.
(<file-database-configuration>): New record type.
(file-database-mcron-jobs): New procedure.
(file-database-service-type): New variable.
* doc/guix.texi (File Search Services): New node.
---
 doc/guix.texi          | 62 ++++++++++++++++++++++++++++++++++++++
 gnu/services/admin.scm | 67 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 129 insertions(+)

diff --git a/doc/guix.texi b/doc/guix.texi
index 853396f776..21ff15ccbc 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -388,6 +388,7 @@ Top
 * Printing Services::           Local and remote printer support.
 * Desktop Services::            D-Bus and desktop services.
 * Sound Services::              ALSA and Pulseaudio services.
+* File Search Services::        Tools to search for files.
 * Database Services::           SQL databases, key-value stores, etc.
 * Mail Services::               IMAP, POP3, SMTP, and all that.
 * Messaging Services::          Messaging services.
@@ -18414,6 +18415,7 @@ Services
 * Printing Services::           Local and remote printer support.
 * Desktop Services::            D-Bus and desktop services.
 * Sound Services::              ALSA and Pulseaudio services.
+* File Search Services::        Tools to search for files.
 * Database Services::           SQL databases, key-value stores, etc.
 * Mail Services::               IMAP, POP3, SMTP, and all that.
 * Messaging Services::          Messaging services.
@@ -24924,6 +24926,66 @@ Sound Services
 
 @end defvar
 
+@node File Search Services
+@subsection File Search Services
+
+@cindex file search
+@cindex searching for a file
+The services in this section populate @dfn{file databases} that let you
+search for files on your machine.  These services are provided by the
+@code{(gnu services admin)} module.
+
+The first one, @code{file-database-service-type}, periodically runs the
+venerable @command{updatedb} command (@pxref{Invoking updatedb,,, find,
+GNU Findutils}).  That command populates a database of file names that
+you can then search with the @command{locate} command (@pxref{Invoing
+locate,,, find, GNU Findutils}), as in this example:
+
+@example
+locate important-notes.txt
+@end example
+
+You can enable this service with its default settings by adding this
+snippet to your operating system services:
+
+@lisp
+(service file-database-service-type)
+@end lisp
+
+This updates the database once a week, excluding files from
+@file{/gnu/store}---these are more usefully handled by @command{guix
+locate} (@pxref{Invoking guix locate}).  You can of course provide a
+custom configuration, as described below.
+
+@defvar file-database-service-type
+This is the type of the file database service, which runs
+@command{updatedb} periodically.  Its associated value must be a
+@code{file-database-configuration} record, as described below.
+@end defvar
+
+@deftp {Data Type} file-database-configuration
+Record type for the @code{file-database-service-type} configuration,
+with the following fields:
+
+@table @asis
+@item @code{package} (default: @code{findutils})
+The GNU@tie{}Findutils package from which the @command{updatedb} command
+is taken.
+
+@item @code{schedule} (default: @code{%default-file-database-update-schedule})
+String or G-exp denoting an mcron schedule for the periodic
+@command{updatedb} job (@pxref{Guile Syntax,,, mcron, GNU@tie{}mcron}).
+
+@item @code{excluded-directories} (default @code{%default-file-database-excluded-directories})
+List of directories to ignore when building the file database.  By
+default, this includes @file{/tmp} and @file{/gnu/store}, which should
+instead be indexed by @command{guix locate} (@pxref{Invoking guix
+locate}).  This list is passed to the @option{--prunepaths} option of
+@command{updatedb} (@pxref{Invoking updatedb,,, find,
+GNU@tie{}Findutils}).
+@end table
+@end deftp
+
 @node Database Services
 @subsection Database Services
 
diff --git a/gnu/services/admin.scm b/gnu/services/admin.scm
index 1c10cfb1f6..57fdfc35c0 100644
--- a/gnu/services/admin.scm
+++ b/gnu/services/admin.scm
@@ -21,11 +21,14 @@
 
 (define-module (gnu services admin)
   #:use-module (gnu packages admin)
+  #:use-module ((gnu packages base)
+                #:select (canonical-package findutils))
   #:use-module (gnu packages certs)
   #:use-module (gnu packages package-management)
   #:use-module (gnu services)
   #:use-module (gnu services mcron)
   #:use-module (gnu services shepherd)
+  #:use-module ((guix store) #:select (%store-prefix))
   #:use-module (guix gexp)
   #:use-module (guix modules)
   #:use-module (guix packages)
@@ -55,6 +58,15 @@ (define-module (gnu services admin)
             log-cleanup-configuration-expiry
             log-cleanup-configuration-schedule
 
+            file-database-service-type
+            file-database-configuration
+            file-database-configuration?
+            file-database-configuration-package
+            file-database-configuration-schedule
+            file-database-configuration-excluded-directories
+            %default-file-database-update-schedule
+            %default-file-database-excluded-directories
+
             unattended-upgrade-service-type
             unattended-upgrade-configuration
             unattended-upgrade-configuration?
@@ -255,6 +267,61 @@ (define log-cleanup-service-type
    (description
     "Periodically delete old log files.")))
 
+\f
+;;;
+;;; File databases.
+;;;
+
+(define %default-file-database-update-schedule
+  ;; Default mcron schedule for the periodic 'updatedb' job: once every
+  ;; Sunday.
+  "10 23 * * 0")
+
+(define %default-file-database-excluded-directories
+  ;; Directories excluded from the 'locate' database.
+  (list (%store-prefix)
+        "/tmp" "/var/tmp" "/var/cache" ".*/\\.cache"
+        "/run/udev"))
+
+(define-record-type* <file-database-configuration>
+  file-database-configuration make-file-database-configuration
+  file-database-configuration?
+  (package              file-database-configuration-package
+                        (default
+                          (let-system (system target)
+                            ;; Unless we're cross-compiling, avoid pulling a
+                            ;; second copy of findutils.
+                            (if target
+                                findutils
+                                (canonical-package findutils)))))
+  (schedule             file-database-configuration-schedule
+                        (default %default-file-database-update-schedule))
+  (excluded-directories file-database-configuration-excluded-directories
+                        (default %default-file-database-excluded-directories)))
+
+(define (file-database-mcron-jobs configuration)
+  (match-record configuration <file-database-configuration>
+    (package schedule excluded-directories)
+    (let ((updatedb (program-file
+                     "updatedb"
+                     #~(execl #$(file-append package "/bin/updatedb")
+                              "updatedb"
+                              #$(string-append "--prunepaths="
+                                               (string-join
+                                                excluded-directories))))))
+      (list #~(job #$schedule #$updatedb)))))
+
+(define file-database-service-type
+  (service-type
+   (name 'file-database)
+   (extensions (list (service-extension mcron-service-type
+                                        file-database-mcron-jobs)))
+   (description
+    "Periodically update the file database used by the @command{locate} command,
+which lets you search for files by name.  The database is created by running
+the @command{updatedb} command.")
+   (default-value (file-database-configuration))))
+
 \f
 ;;;
 ;;; Unattended upgrade.
-- 
2.40.1

[bug#64471] [PATCH 2/2] services: Add 'package-database' service.

[Ludovic Courtès]

* gnu/services/admin.scm (%default-package-database-update-schedule):
New variable.
(<package-database-configuration>): New record type.
(package-database-mcron-jobs): New procedure.
(package-database-service-type): New variable.
* doc/guix.texi (File Search Services): Document it.
---
 doc/guix.texi          | 49 +++++++++++++++++++++++++++++++++++++++++-
 gnu/services/admin.scm | 49 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 97 insertions(+), 1 deletion(-)

diff --git a/doc/guix.texi b/doc/guix.texi
index 21ff15ccbc..05cfdb9bc7 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -4481,7 +4481,9 @@ Invoking guix locate
 exist or is too old, it falls back to the per-user database, by default
 under @file{~/.cache/guix/locate}.  On a multi-user system,
 administrators may want to periodically update the system-wide database
-so that all users can benefit from it.
+so that all users can benefit from it, for instance by setting up
+@code{package-database-service-type} (@pxref{File Search Services,
+@code{package-database-service-type}}).
 
 The general syntax is:
 
@@ -24986,6 +24988,51 @@ File Search Services
 @end table
 @end deftp
 
+The second service, @code{package-database-service-type}, builds the
+database used by @command{guix locate}, which lets you search for
+packages that contain a given file (@pxref{Invoking guix locate}).  The
+service periodically updates a system-wide database, which will be
+readily available to anyone running @command{guix locate} on the system.
+To use this service with its default settings, add this snippet to your
+service list:
+
+@lisp
+(service package-database-service-type)
+@end lisp
+
+This will run @command{guix locate --update} once a week.
+
+@defvar package-database-service-type
+This is the service type for periodic @command{guix locate} updates
+(@pxref{Invoking guix locate}).  Its value must be a
+@code{package-database-configuration} record, as shown below.
+@end defvar
+
+@deftp {Data Type} package-database-configuration
+Data type to configure periodic package database updates.  It has the
+following fields:
+
+@table @asis
+@item @code{package} (default: @code{guix})
+The Guix package to use.
+
+@item @code{schedule} (default: @code{%default-package-database-update-schedule})
+String or G-exp denoting an mcron schedule for the periodic
+@command{guix locate --update} job (@pxref{Guile Syntax,,, mcron,
+GNU@tie{}mcron}).
+
+@item @code{method} (default: @code{'store})
+Indexing method for @command{guix locate}.  The default value,
+@code{'store}, yields a more complete database but is relatively
+expensive in terms of CPU and input/output.
+
+@item @code{channels} (default: @code{#~%default-channels})
+G-exp denoting the channels to use when updating the database
+(@pxref{Channels}).
+@end table
+@end deftp
+
+
 @node Database Services
 @subsection Database Services
 
diff --git a/gnu/services/admin.scm b/gnu/services/admin.scm
index 57fdfc35c0..f16880029f 100644
--- a/gnu/services/admin.scm
+++ b/gnu/services/admin.scm
@@ -28,6 +28,8 @@ (define-module (gnu services admin)
   #:use-module (gnu services)
   #:use-module (gnu services mcron)
   #:use-module (gnu services shepherd)
+  #:use-module (gnu system accounts)
+  #:use-module ((gnu system shadow) #:select (account-service-type))
   #:use-module ((guix store) #:select (%store-prefix))
   #:use-module (guix gexp)
   #:use-module (guix modules)
@@ -67,6 +69,14 @@ (define-module (gnu services admin)
             %default-file-database-update-schedule
             %default-file-database-excluded-directories
 
+            package-database-service-type
+            package-database-configuration
+            package-database-configuration?
+            package-database-configuration-package
+            package-database-configuration-schedule
+            package-database-configuration-method
+            package-database-configuration-channels
+
             unattended-upgrade-service-type
             unattended-upgrade-configuration
             unattended-upgrade-configuration?
@@ -322,6 +332,45 @@ (define file-database-service-type
 the @command{updatedb} command.")
    (default-value (file-database-configuration))))
 
+(define %default-package-database-update-schedule
+  ;; Default mcron schedule for the periodic 'guix locate --update' job: once
+  ;; every Monday.
+  "10 23 * * 1")
+
+(define-record-type* <package-database-configuration>
+  package-database-configuration make-package-database-configuration
+  package-database-configuration?
+  (package   package-database-configuration-package
+             (default guix))
+  (schedule  package-database-configuration-schedule
+             (default %default-package-database-update-schedule))
+  (method    package-database-configuration-method
+             (default 'store))
+  (channels  package-database-configuration-channels
+             (default #~%default-channels)))
+
+(define (package-database-mcron-jobs configuration)
+  (match-record configuration <package-database-configuration>
+    (package schedule method channels)
+    (let ((channels (scheme-file "channels.scm" channels)))
+      (list #~(job #$schedule
+                   ;; XXX: The whole thing's running as "root" just because it
+                   ;; needs write access to /var/cache/guix/locate.
+                   (string-append #$(file-append package "/bin/guix")
+                                  " time-machine -C " #$channels
+                                  " -- locate --update --method="
+                                  #$(symbol->string method)))))))
+
+(define package-database-service-type
+  (service-type
+   (name 'package-database)
+   (extensions (list (service-extension mcron-service-type
+                                        package-database-mcron-jobs)))
+   (description
+    "Periodically update the package database used by the @code{guix locate} command,
+which lets you search for packages that provide a given file.")
+   (default-value (package-database-configuration))))
+
 \f
 ;;;
 ;;; Unattended upgrade.
-- 
2.40.1

[bug#64471] [PATCH 1/2] services: Add 'file-database' service.

[Bruno Victal]

Hi Ludo’,

On 2023-07-05 11:16, Ludovic Courtès wrote:
> +(define-record-type* <file-database-configuration>
> +  file-database-configuration make-file-database-configuration
> +  file-database-configuration?
> +  (package              file-database-configuration-package
> +                        (default
> +                          (let-system (system target)
> +                            ;; Unless we're cross-compiling, avoid pulling a
> +                            ;; second copy of findutils.
> +                            (if target
> +                                findutils
> +                                (canonical-package findutils)))))
> +  (schedule             file-database-configuration-schedule
> +                        (default %default-file-database-update-schedule))
> +  (excluded-directories file-database-configuration-excluded-directories
> +                        (default %default-file-database-excluded-directories)))

How about using define-configuration instead to have the documentation neatly
in sync with the fields?

> +
> +(define (file-database-mcron-jobs configuration)
> +  (match-record configuration <file-database-configuration>
> +    (package schedule excluded-directories)
> +    (let ((updatedb (program-file
> +                     "updatedb"
> +                     #~(execl #$(file-append package "/bin/updatedb")
> +                              "updatedb"
> +                              #$(string-append "--prunepaths="
> +                                               (string-join
> +                                                excluded-directories))))))
> +      (list #~(job #$schedule #$updatedb)))))

I'm afraid #$schedule might be insufficient if this is a _mcron_ time-spec.
There's an elaborate dance done by fstrim-service-type to handle the more exotic
mcron time expressions, perhaps you can reuse it here?


-- 
Furthermore, I consider that nonfree software must be eradicated.

Cheers,
Bruno.

[bug#64471] [PATCH 0/2] File database update services

[Ludovic Courtès]

Hello,

Bruno Victal <mirai@makinata.eu> skribis:

> On 2023-07-05 11:16, Ludovic Courtès wrote:
>> +(define-record-type* <file-database-configuration>
>> +  file-database-configuration make-file-database-configuration
>> +  file-database-configuration?
>> +  (package              file-database-configuration-package
>> +                        (default
>> +                          (let-system (system target)
>> +                            ;; Unless we're cross-compiling, avoid pulling a
>> +                            ;; second copy of findutils.
>> +                            (if target
>> +                                findutils
>> +                                (canonical-package findutils)))))
>> +  (schedule             file-database-configuration-schedule
>> +                        (default %default-file-database-update-schedule))
>> +  (excluded-directories file-database-configuration-excluded-directories
>> +                        (default %default-file-database-excluded-directories)))
>
> How about using define-configuration instead to have the documentation neatly
> in sync with the fields?

Hmm, good point, I’ll take a look.

>> +(define (file-database-mcron-jobs configuration)
>> +  (match-record configuration <file-database-configuration>
>> +    (package schedule excluded-directories)
>> +    (let ((updatedb (program-file
>> +                     "updatedb"
>> +                     #~(execl #$(file-append package "/bin/updatedb")
>> +                              "updatedb"
>> +                              #$(string-append "--prunepaths="
>> +                                               (string-join
>> +                                                excluded-directories))))))
>> +      (list #~(job #$schedule #$updatedb)))))
>
> I'm afraid #$schedule might be insufficient if this is a _mcron_ time-spec.
> There's an elaborate dance done by fstrim-service-type to handle the more exotic
> mcron time expressions, perhaps you can reuse it here?

I’m not sure what fstrim-service-type is trying to achieve with this:

    #~(job
       ;; Note: The “if” below is to ensure that
       ;; lists are ungexp'd correctly since @var{schedule}
       ;; can be either a procedure, a string or a list.
       #$(if (list? schedule)
             #~'(#$@schedule)
             schedule)
       …")

If we simply have:

  #~(job #$schedule …)

then ‘schedule’ can be anything you might expect, like:

  • "0 * * * *"         ;string

  • #~(next-hour …)     ;gexp

  • #~(lambda (x) …)    ;another gexp

What’s the problem? :-)

Ludo’.

[bug#64471] [PATCH v2 1/2] services: Add 'file-database' service.

[Ludovic Courtès]

* gnu/services/admin.scm (%default-file-database-update-schedule)
(%default-file-database-excluded-directories): New variables.
(<file-database-configuration>): New record type.
(file-database-mcron-jobs): New procedure.
(file-database-service-type): New variable.
* doc/guix.texi (File Search Services): New node.
---
 doc/guix.texi          | 62 +++++++++++++++++++++++++++++++
 gnu/services/admin.scm | 83 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 145 insertions(+)

Change since v1: use of 'define-configuration' instead of
'define-record-type*'.

However, I am not using the generated documentation due
to <https://issues.guix.gnu.org/64754>.  (Overall I'm not
fully satisfied with 'define-configuration'.)

Thoughts?

Ludo'.

diff --git a/doc/guix.texi b/doc/guix.texi
index 1d8ebcd72f..1d5f7c6b47 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -388,6 +388,7 @@ Top
 * Printing Services::           Local and remote printer support.
 * Desktop Services::            D-Bus and desktop services.
 * Sound Services::              ALSA and Pulseaudio services.
+* File Search Services::        Tools to search for files.
 * Database Services::           SQL databases, key-value stores, etc.
 * Mail Services::               IMAP, POP3, SMTP, and all that.
 * Messaging Services::          Messaging services.
@@ -18428,6 +18429,7 @@ Services
 * Printing Services::           Local and remote printer support.
 * Desktop Services::            D-Bus and desktop services.
 * Sound Services::              ALSA and Pulseaudio services.
+* File Search Services::        Tools to search for files.
 * Database Services::           SQL databases, key-value stores, etc.
 * Mail Services::               IMAP, POP3, SMTP, and all that.
 * Messaging Services::          Messaging services.
@@ -24938,6 +24940,66 @@ Sound Services
 
 @end defvar
 
+@node File Search Services
+@subsection File Search Services
+
+@cindex file search
+@cindex searching for a file
+The services in this section populate @dfn{file databases} that let you
+search for files on your machine.  These services are provided by the
+@code{(gnu services admin)} module.
+
+The first one, @code{file-database-service-type}, periodically runs the
+venerable @command{updatedb} command (@pxref{Invoking updatedb,,, find,
+GNU Findutils}).  That command populates a database of file names that
+you can then search with the @command{locate} command (@pxref{Invoing
+locate,,, find, GNU Findutils}), as in this example:
+
+@example
+locate important-notes.txt
+@end example
+
+You can enable this service with its default settings by adding this
+snippet to your operating system services:
+
+@lisp
+(service file-database-service-type)
+@end lisp
+
+This updates the database once a week, excluding files from
+@file{/gnu/store}---these are more usefully handled by @command{guix
+locate} (@pxref{Invoking guix locate}).  You can of course provide a
+custom configuration, as described below.
+
+@defvar file-database-service-type
+This is the type of the file database service, which runs
+@command{updatedb} periodically.  Its associated value must be a
+@code{file-database-configuration} record, as described below.
+@end defvar
+
+@deftp {Data Type} file-database-configuration
+Record type for the @code{file-database-service-type} configuration,
+with the following fields:
+
+@table @asis
+@item @code{package} (default: @code{findutils})
+The GNU@tie{}Findutils package from which the @command{updatedb} command
+is taken.
+
+@item @code{schedule} (default: @code{%default-file-database-update-schedule})
+String or G-exp denoting an mcron schedule for the periodic
+@command{updatedb} job (@pxref{Guile Syntax,,, mcron, GNU@tie{}mcron}).
+
+@item @code{excluded-directories} (default @code{%default-file-database-excluded-directories})
+List of directories to ignore when building the file database.  By
+default, this includes @file{/tmp} and @file{/gnu/store}, which should
+instead be indexed by @command{guix locate} (@pxref{Invoking guix
+locate}).  This list is passed to the @option{--prunepaths} option of
+@command{updatedb} (@pxref{Invoking updatedb,,, find,
+GNU@tie{}Findutils}).
+@end table
+@end deftp
+
 @node Database Services
 @subsection Database Services
 
diff --git a/gnu/services/admin.scm b/gnu/services/admin.scm
index 1c10cfb1f6..636367a6f3 100644
--- a/gnu/services/admin.scm
+++ b/gnu/services/admin.scm
@@ -21,16 +21,21 @@
 
 (define-module (gnu services admin)
   #:use-module (gnu packages admin)
+  #:use-module ((gnu packages base)
+                #:select (canonical-package findutils))
   #:use-module (gnu packages certs)
   #:use-module (gnu packages package-management)
   #:use-module (gnu services)
+  #:use-module (gnu services configuration)
   #:use-module (gnu services mcron)
   #:use-module (gnu services shepherd)
+  #:use-module ((guix store) #:select (%store-prefix))
   #:use-module (guix gexp)
   #:use-module (guix modules)
   #:use-module (guix packages)
   #:use-module (guix records)
   #:use-module (srfi srfi-1)
+  #:use-module (ice-9 match)
   #:use-module (ice-9 vlist)
   #:export (%default-rotations
             %rotated-files
@@ -55,6 +60,15 @@ (define-module (gnu services admin)
             log-cleanup-configuration-expiry
             log-cleanup-configuration-schedule
 
+            file-database-service-type
+            file-database-configuration
+            file-database-configuration?
+            file-database-configuration-package
+            file-database-configuration-schedule
+            file-database-configuration-excluded-directories
+            %default-file-database-update-schedule
+            %default-file-database-excluded-directories
+
             unattended-upgrade-service-type
             unattended-upgrade-configuration
             unattended-upgrade-configuration?
@@ -255,6 +269,75 @@ (define log-cleanup-service-type
    (description
     "Periodically delete old log files.")))
 
+\f
+;;;
+;;; File databases.
+;;;
+
+(define %default-file-database-update-schedule
+  ;; Default mcron schedule for the periodic 'updatedb' job: once every
+  ;; Sunday.
+  "10 23 * * 0")
+
+(define %default-file-database-excluded-directories
+  ;; Directories excluded from the 'locate' database.
+  (list (%store-prefix)
+        "/tmp" "/var/tmp" "/var/cache" ".*/\\.cache"
+        "/run/udev"))
+
+(define (string-or-gexp? obj)
+  (or (string? obj) (gexp? obj)))
+
+(define string-list?
+  (match-lambda
+    (((? string) ...) #t)
+    (_ #f)))
+
+(define-configuration/no-serialization file-database-configuration
+  (package
+    (file-like (let-system (system target)
+                 ;; Unless we're cross-compiling, avoid pulling a second copy
+                 ;; of findutils.
+                 (if target
+                     findutils
+                     (canonical-package findutils))))
+    "The GNU@tie{}Findutils package from which the @command{updatedb} command
+is taken.")
+  (schedule
+   (string-or-gexp %default-file-database-update-schedule)
+   "String or G-exp denoting an mcron schedule for the periodic
+@command{updatedb} job (@pxref{Guile Syntax,,, mcron, GNU@tie{}mcron}).")
+  (excluded-directories
+   (string-list %default-file-database-excluded-directories)
+   "List of directories to ignore when building the file database.  By
+default, this includes @file{/tmp} and @file{/gnu/store}, which should instead
+be indexed by @command{guix locate} (@pxref{Invoking guix locate}).  This list
+is passed to the @option{--prunepaths} option of
+@command{updatedb} (@pxref{Invoking updatedb,,, find, GNU@tie{}Findutils})."))
+
+(define (file-database-mcron-jobs configuration)
+  (match-record configuration <file-database-configuration>
+    (package schedule excluded-directories)
+    (let ((updatedb (program-file
+                     "updatedb"
+                     #~(execl #$(file-append package "/bin/updatedb")
+                              "updatedb"
+                              #$(string-append "--prunepaths="
+                                               (string-join
+                                                excluded-directories))))))
+      (list #~(job #$schedule #$updatedb)))))
+
+(define file-database-service-type
+  (service-type
+   (name 'file-database)
+   (extensions (list (service-extension mcron-service-type
+                                        file-database-mcron-jobs)))
+   (description
+    "Periodically update the file database used by the @command{locate} command,
+which lets you search for files by name.  The database is created by running
+the @command{updatedb} command.")
+   (default-value (file-database-configuration))))
+
 \f
 ;;;
 ;;; Unattended upgrade.

base-commit: 283969d0c527aa41e65bb4f5c2a7fa3baf86c49a
-- 
2.41.0

[bug#64471] [PATCH v2 2/2] services: Add 'package-database' service.

[Ludovic Courtès]

* gnu/services/admin.scm (%default-package-database-update-schedule):
New variable.
(<package-database-configuration>): New record type.
(package-database-mcron-jobs): New procedure.
(package-database-service-type): New variable.
* doc/guix.texi (File Search Services): Document it.
---
 doc/guix.texi          | 49 +++++++++++++++++++++++++++++++++++++-
 gnu/services/admin.scm | 53 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 101 insertions(+), 1 deletion(-)

diff --git a/doc/guix.texi b/doc/guix.texi
index 1d5f7c6b47..833865f009 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -4481,7 +4481,9 @@ Invoking guix locate
 exist or is too old, it falls back to the per-user database, by default
 under @file{~/.cache/guix/locate}.  On a multi-user system,
 administrators may want to periodically update the system-wide database
-so that all users can benefit from it.
+so that all users can benefit from it, for instance by setting up
+@code{package-database-service-type} (@pxref{File Search Services,
+@code{package-database-service-type}}).
 
 The general syntax is:
 
@@ -25000,6 +25002,51 @@ File Search Services
 @end table
 @end deftp
 
+The second service, @code{package-database-service-type}, builds the
+database used by @command{guix locate}, which lets you search for
+packages that contain a given file (@pxref{Invoking guix locate}).  The
+service periodically updates a system-wide database, which will be
+readily available to anyone running @command{guix locate} on the system.
+To use this service with its default settings, add this snippet to your
+service list:
+
+@lisp
+(service package-database-service-type)
+@end lisp
+
+This will run @command{guix locate --update} once a week.
+
+@defvar package-database-service-type
+This is the service type for periodic @command{guix locate} updates
+(@pxref{Invoking guix locate}).  Its value must be a
+@code{package-database-configuration} record, as shown below.
+@end defvar
+
+@deftp {Data Type} package-database-configuration
+Data type to configure periodic package database updates.  It has the
+following fields:
+
+@table @asis
+@item @code{package} (default: @code{guix})
+The Guix package to use.
+
+@item @code{schedule} (default: @code{%default-package-database-update-schedule})
+String or G-exp denoting an mcron schedule for the periodic
+@command{guix locate --update} job (@pxref{Guile Syntax,,, mcron,
+GNU@tie{}mcron}).
+
+@item @code{method} (default: @code{'store})
+Indexing method for @command{guix locate}.  The default value,
+@code{'store}, yields a more complete database but is relatively
+expensive in terms of CPU and input/output.
+
+@item @code{channels} (default: @code{#~%default-channels})
+G-exp denoting the channels to use when updating the database
+(@pxref{Channels}).
+@end table
+@end deftp
+
+
 @node Database Services
 @subsection Database Services
 
diff --git a/gnu/services/admin.scm b/gnu/services/admin.scm
index 636367a6f3..0c24cedd43 100644
--- a/gnu/services/admin.scm
+++ b/gnu/services/admin.scm
@@ -29,6 +29,8 @@ (define-module (gnu services admin)
   #:use-module (gnu services configuration)
   #:use-module (gnu services mcron)
   #:use-module (gnu services shepherd)
+  #:use-module (gnu system accounts)
+  #:use-module ((gnu system shadow) #:select (account-service-type))
   #:use-module ((guix store) #:select (%store-prefix))
   #:use-module (guix gexp)
   #:use-module (guix modules)
@@ -69,6 +71,14 @@ (define-module (gnu services admin)
             %default-file-database-update-schedule
             %default-file-database-excluded-directories
 
+            package-database-service-type
+            package-database-configuration
+            package-database-configuration?
+            package-database-configuration-package
+            package-database-configuration-schedule
+            package-database-configuration-method
+            package-database-configuration-channels
+
             unattended-upgrade-service-type
             unattended-upgrade-configuration
             unattended-upgrade-configuration?
@@ -338,6 +348,49 @@ (define file-database-service-type
 the @command{updatedb} command.")
    (default-value (file-database-configuration))))
 
+(define %default-package-database-update-schedule
+  ;; Default mcron schedule for the periodic 'guix locate --update' job: once
+  ;; every Monday.
+  "10 23 * * 1")
+
+(define-configuration/no-serialization package-database-configuration
+  (package (file-like guix)
+           "The Guix package to use.")
+  (schedule (string-or-gexp
+             %default-package-database-update-schedule)
+            "String or G-exp denoting an mcron schedule for the periodic
+@command{guix locate --update} job (@pxref{Guile Syntax,,, mcron,
+GNU@tie{}mcron}).")
+  (method    (symbol 'store)
+             "Indexing method for @command{guix locate}.  The default value,
+@code{'store}, yields a more complete database but is relatively expensive in
+terms of CPU and input/output.")
+  (channels (gexp #~%default-channels)
+            "G-exp denoting the channels to use when updating the database
+(@pxref{Channels})."))
+
+(define (package-database-mcron-jobs configuration)
+  (match-record configuration <package-database-configuration>
+    (package schedule method channels)
+    (let ((channels (scheme-file "channels.scm" channels)))
+      (list #~(job #$schedule
+                   ;; XXX: The whole thing's running as "root" just because it
+                   ;; needs write access to /var/cache/guix/locate.
+                   (string-append #$(file-append package "/bin/guix")
+                                  " time-machine -C " #$channels
+                                  " -- locate --update --method="
+                                  #$(symbol->string method)))))))
+
+(define package-database-service-type
+  (service-type
+   (name 'package-database)
+   (extensions (list (service-extension mcron-service-type
+                                        package-database-mcron-jobs)))
+   (description
+    "Periodically update the package database used by the @code{guix locate} command,
+which lets you search for packages that provide a given file.")
+   (default-value (package-database-configuration))))
+
 \f
 ;;;
 ;;; Unattended upgrade.
-- 
2.41.0

[bug#64471] [PATCH 0/2] File database update services

[Bruno Victal]

Hi Ludo’,

On 2023-07-17 21:22, Ludovic Courtès wrote:
> Bruno Victal <mirai@makinata.eu> skribis:
> 
>>
>> I'm afraid #$schedule might be insufficient if this is a _mcron_ time-spec.
>> There's an elaborate dance done by fstrim-service-type to handle the more exotic
>> mcron time expressions, perhaps you can reuse it here?
> 
> I’m not sure what fstrim-service-type is trying to achieve with this:
> 
>     #~(job
>        ;; Note: The “if” below is to ensure that
>        ;; lists are ungexp'd correctly since @var{schedule}
>        ;; can be either a procedure, a string or a list.
>        #$(if (list? schedule)
>              #~'(#$@schedule)
>              schedule)
>        …")
> 
> If we simply have:
> 
>   #~(job #$schedule …)
> 
> then ‘schedule’ can be anything you might expect, like:
> 
>   • "0 * * * *"         ;string
> 
>   • #~(next-hour …)     ;gexp
> 
>   • #~(lambda (x) …)    ;another gexp
> 
> What’s the problem? :-)

There's a third choice for that argument: a staged expression/list, hence
the gexp/ungexp dance.

[1]: <https://www.gnu.org/software/mcron/manual/mcron.html#Guile-Syntax>
[2]: <https://www.gnu.org/software/mcron/manual/mcron.html#Extended-Guile-examples>


-- 
Furthermore, I consider that nonfree software must be eradicated.

Cheers,
Bruno.

[bug#64471] [PATCH v2 1/2] services: Add 'file-database' service.

[Bruno Victal]

On 2023-07-20 22:22, Ludovic Courtès wrote:

> +(define string-list?
> +  (match-lambda
> +    (((? string) ...) #t)
> +    (_ #f)))

There's a procedure 'list-of' from (gnu services configuration) that you can use
to define these kinds of procedures. In fact, there's already a list-of-strings?
predicate as a starting point within said module that you can use instead.

-- 
Furthermore, I consider that nonfree software must be eradicated.

Cheers,
Bruno.

bug#64471: [PATCH 0/2] File database update services

[Ludovic Courtès]

Ludovic Courtès <ludo@gnu.org> skribis:

>   services: Add 'file-database' service.
>   services: Add 'package-database' service.

Pushed as b3a2b3e7238161ebd86c7609f68e8f1e9c1dd6b7!

Ludo’.