services: postgresql: Change service default socket directory.

Fixes <https://bugs.gnu.org/46737>.

PostgreSQL running with a different socket directory to the default one in the
package itself breaks some services, this commit restores the previous
behaviour where PostgreSQL by default will run with a socket directory that
matches the default used by PostgreSQL packaged for Guix.

Switching to a different default value can happen, but only alongside changing
the PostgreSQL package.

* gnu/services/databases.scm (<postgresql-config-file>)[socket-directory]:
Change default to #false.
* doc/guix.texi (Database Services): Update documentation, and specify a
different value for disabling connections via sockets.
* gnu/tests/guix.scm (%guix-data-service-os): Use default PostgreSQL
behaviour.
* gnu/tests/monitoring.scm (%zabbix-os): Likewise.
* gnu/tests/web.scm (patchwork-os): Likewise.

Signed-off-by: Leo Famulari <leo@famulari.name>

doc/guix.texi

@@ -19830,12 +19830,15 @@ configuration.
 @item @code{ident-file} (default: @code{%default-postgres-ident})
 Filename or G-expression for the user name mapping configuration.
 
-@item @code{socket-directory} (default: @code{"/var/run/postgresql"})
+@item @code{socket-directory} (default: @code{#false})
 Specifies the directory of the Unix-domain socket(s) on which PostgreSQL
-is to listen for connections from client applications.  If set to
-@code{#false} PostgreSQL does not listen on any Unix-domain sockets, in
+is to listen for connections from client applications. If set to
+@code{""} PostgreSQL does not listen on any Unix-domain sockets, in
 which case only TCP/IP sockets can be used to connect to the server.
 
+By default, the @code{#false} value means the PostgreSQL default value
+will be used, which is currently @samp{/tmp}.
+
 @item @code{extra-config} (default: @code{'()})
 List of additional keys and values to include in the PostgreSQL config
 file.  Each entry in the list should be a list where the first element

gnu/services/databases.scm

@@ -115,7 +115,7 @@ host	all	all	::1/128 	md5"))
   (ident-file        postgresql-config-file-ident-file
                      (default %default-postgres-ident))
   (socket-directory  postgresql-config-file-socket-directory
-                     (default "/var/run/postgresql"))
+                     (default #false))
   (extra-config      postgresql-config-file-extra-config
                      (default '())))
 

gnu/tests/guix.scm

@@ -164,10 +164,7 @@
                             "
 local	all	all			trust
 host	all	all	127.0.0.1/32 	trust
-host	all	all	::1/128 	trust"))
-               ;; XXX: Remove when postgresql default socket directory is
-               ;; changed to /var/run/postgresql.
-               (socket-directory #f)))))
+host	all	all	::1/128 	trust"))))))
    (service guix-data-service-type
             (guix-data-service-configuration
              (host "0.0.0.0")))

gnu/tests/monitoring.scm

@@ -309,12 +309,7 @@ zabbix||{}
           (service dhcp-client-service-type)
           (service postgresql-service-type
                    (postgresql-configuration
-                    (postgresql postgresql)
-                   ;; XXX: Remove when postgresql default socket directory is
-                    ;; changed to /var/run/postgresql.
-                    (config-file
-                     (postgresql-config-file
-                      (socket-directory #f)))))
+                    (postgresql postgresql)))
           (service zabbix-front-end-service-type
                    (zabbix-front-end-configuration
                     (db-password "zabbix")))

gnu/tests/web.scm

@@ -569,12 +569,7 @@ HTTP-PORT."
                (listen '("8080"))))))
    (service postgresql-service-type
             (postgresql-configuration
-             (postgresql postgresql-10)
-             ;; XXX: Remove when postgresql default socket directory is
-             ;; changed to /var/run/postgresql.
-             (config-file
-              (postgresql-config-file
-               (socket-directory #f)))))
+             (postgresql postgresql-10)))
    (service patchwork-service-type
             (patchwork-configuration
              (patchwork patchwork)