services: base: Deprecate 'pam-limits-service' procedure.

* doc/guix.texi (Base Services): Replace pam-limits-service with pam-limits-service-type.
* gnu/packages/benchmark.scm (python-locust)[description]: Update index anchor to manual.
* gnu/services/base.scm (pam-limits-service-type): Set default value.
(pam-limits-service): Deprecate procedure.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

doc/guix.texi

@@ -18959,7 +18959,6 @@ will fail if @var{device} does not exist.
 @end table
 @end deftp
 
-@anchor{pam-limits-service}
 @cindex session limits
 @cindex ulimit
 @cindex priority
@@ -18967,22 +18966,28 @@ will fail if @var{device} does not exist.
 @cindex jackd
 @cindex nofile
 @cindex open file descriptors
-@deffn {Scheme Procedure} pam-limits-service [#:limits @code{'()}]
-
-Return a service that installs a configuration file for the
+@anchor{pam-limits-service-type}
+@defvar pam-limits-service-type
+Type of the service that installs a configuration file for the
 @uref{http://linux-pam.org/Linux-PAM-html/sag-pam_limits.html,
-@code{pam_limits} module}.  The procedure optionally takes a list of
-@code{pam-limits-entry} values, which can be used to specify
-@code{ulimit} limits and @code{nice} priority limits to user sessions.
+@code{pam_limits} module}.  The value for this service type is
+a file-like object containing a list of @code{pam-limits-entry} values
+which can be used to specify @code{ulimit} limits and @code{nice}
+priority limits to user sessions.
 
 The following limits definition sets two hard and soft limits for all
 login sessions of users in the @code{realtime} group:
 
 @lisp
-(pam-limits-service
- (list
-  (pam-limits-entry "@@realtime" 'both 'rtprio 99)
-  (pam-limits-entry "@@realtime" 'both 'memlock 'unlimited)))
+(service
+  pam-limits-service-type
+  (plain-file
+    "limits.conf"
+    (string-join
+      (map pam-limits-entry->string
+        (list (pam-limits-entry "@@realtime" 'both 'rtprio 99)
+              (pam-limits-entry "@@realtime" 'both 'memlock 'unlimited)))
+      "\n")))
 @end lisp
 
 The first entry increases the maximum realtime priority for
@@ -18994,9 +18999,11 @@ Another useful example is raising the maximum number of open file
 descriptors that can be used:
 
 @lisp
-(pam-limits-service
- (list
-  (pam-limits-entry "*" 'both 'nofile 100000)))
+(service
+  pam-limits-service-type
+  (plain-file
+    "limits.conf"
+    (pam-limits-entry->string (pam-limits-entry "*" 'both 'nofile 100000))))
 @end lisp
 
 In the above example, the asterisk means the limit should apply to any
@@ -19005,7 +19012,7 @@ maximum system value visible in the @file{/proc/sys/fs/file-max} file,
 else the users would be prevented from login in.  For more information
 about the Pluggable Authentication Module (PAM) limits, refer to the
 @samp{pam_limits} man page from the @code{linux-pam} package.
-@end deffn
+@end defvar
 
 @defvar greetd-service-type
 @uref{https://git.sr.ht/~kennylevinsen/greetd, @code{greetd}} is a minimal and

gnu/packages/benchmark.scm

@@ -458,7 +458,7 @@ test any system or protocol.
 
 Note: Locust will complain if the available open file descriptors limit for
 the user is too low.  To raise such limit on a Guix System, refer to
-@samp{info guix --index-search=pam-limits-service}.")
+@samp{info guix --index-search=pam-limits-service-type}.")
     (license license:expat)))
 
 (define-public interbench

gnu/services/base.scm

@@ -246,7 +246,7 @@
             kmscon-service-type
 
             pam-limits-service-type
-            pam-limits-service
+            pam-limits-service  ; deprecated
 
             greetd-service-type
             greetd-configuration
@@ -1616,9 +1616,11 @@ information on the configuration file syntax."
      (description
       "Install the specified resource usage limits by populating
 @file{/etc/security/limits.conf} and using the @code{pam_limits}
-authentication module."))))
+authentication module.")
+     (default-value (plain-file "limits.conf" "")))))
 
-(define* (pam-limits-service #:optional (limits '()))
+(define-deprecated (pam-limits-service #:optional (limits '()))
+  pam-limits-service-type
   "Return a service that makes selected programs respect the list of
 pam-limits-entry specified in LIMITS via pam_limits.so."
   (service pam-limits-service-type