services: postgresql: Add locale to configuration

* gnu/services/databases.scm (<postgresql-configuration>): Add locale
  field.
  (postgresql-shepherd-service): Pass locale to initdb.
  (postgresql-service): Add locale default.

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

doc/guix.texi

@@ -10167,13 +10167,13 @@ The @code{(gnu services databases)} module provides the following services.
 
 @deffn {Scheme Procedure} postgresql-service [#:postgresql postgresql] @
        [#:config-file] [#:data-directory ``/var/lib/postgresql/data''] @
-       [#:port 5432]
+       [#:port 5432] [#:locale ``en_US.utf8'']
 Return a service that runs @var{postgresql}, the PostgreSQL database
 server.
 
-The PostgreSQL daemon loads its runtime configuration from
-@var{config-file}, stores the database cluster in @var{data-directory} and
-listens on @var{port}.
+The PostgreSQL daemon loads its runtime configuration from @var{config-file},
+creates a database cluster with @var{locale} as the default
+locale, stored in @var{data-directory}.  It then listens on @var{port}.
 @end deffn
 
 @deffn {Scheme Procedure} mysql-service [#:config (mysql-configuration)]

gnu/services/databases.scm

@@ -50,6 +50,8 @@
                   (default postgresql))
   (port           postgresql-configuration-port
                   (default 5432))
+  (locale         postgresql-configuration-locale
+                  (default "en_US.utf8"))
   (config-file    postgresql-configuration-file)
   (data-directory postgresql-configuration-data-directory))
 
@@ -82,13 +84,18 @@ host	all	all	::1/128 	trust"))
 
 (define postgresql-activation
   (match-lambda
-    (($ <postgresql-configuration> postgresql port config-file data-directory)
+    (($ <postgresql-configuration> postgresql port locale config-file data-directory)
      #~(begin
          (use-modules (guix build utils)
                       (ice-9 match))
 
          (let ((user (getpwnam "postgres"))
-               (initdb (string-append #$postgresql "/bin/initdb")))
+               (initdb (string-append #$postgresql "/bin/initdb"))
+               (initdb-args
+                (append
+                 (if #$locale
+                     (list (string-append "--locale=" #$locale))
+                     '()))))
            ;; Create db state directory.
            (mkdir-p #$data-directory)
            (chown #$data-directory (passwd:uid user) (passwd:gid user))
@@ -103,14 +110,19 @@ host	all	all	::1/128 	trust"))
                 (lambda ()
                   (setgid (passwd:gid user))
                   (setuid (passwd:uid user))
-                  (primitive-exit (system* initdb "-D" #$data-directory)))
+                  (primitive-exit
+                   (apply system*
+                          initdb
+                          "-D"
+                          #$data-directory
+                          initdb-args)))
                 (lambda ()
                   (primitive-exit 1))))
              (pid (waitpid pid))))))))
 
 (define postgresql-shepherd-service
   (match-lambda
-    (($ <postgresql-configuration> postgresql port config-file data-directory)
+    (($ <postgresql-configuration> postgresql port locale config-file data-directory)
      (let ((start-script
             ;; Wrapper script that switches to the 'postgres' user before
             ;; launching daemon.
@@ -144,6 +156,7 @@ host	all	all	::1/128 	trust"))
 
 (define* (postgresql-service #:key (postgresql postgresql)
                              (port 5432)
+                             (locale "en_US.utf8")
                              (config-file %default-postgres-config)
                              (data-directory "/var/lib/postgresql/data"))
   "Return a service that runs @var{postgresql}, the PostgreSQL database server.
@@ -154,6 +167,7 @@ and stores the database cluster in @var{data-directory}."
            (postgresql-configuration
             (postgresql postgresql)
             (port port)
+            (locale locale)
             (config-file config-file)
             (data-directory data-directory))))