services: databases: Don't specify a default postgresql version.

Currently, if the postgresql package major version changes, this is going to
break the service upon upgrade, because PostgreSQL will reject the data files
from the differing major version of the service.

Because it's important to either keep running a particular major version, or
intentionally upgrade, I think the configuration would be better with no
default. I think this is also going to be helpful when trying to assist users
upgrading PostgreSQL.

* gnu/services/databases.scm (<postgresql-configuration>): Remove default for
postgresql.
(postgresql-service-type): Remove the default value.
* gnu/tests/databases.scm (%postgresql-os): Update accordingly.
* gnu/tests/guix.scm (%guix-data-service-os): Update accordingly.
* gnu/tests/monitoring.scm (%zabbix-os): Update accordingly.
* gnu/tests/web.scm (patchwork-os): Update accordingly.
* doc/guix.texi (PostgreSQL): Update accordingly.

4 files changed, 10 insertions, 3 deletions

diff --git a/gnu/tests/databases.scm b/gnu/tests/databases.scm
index e0544bbcd2e..d3045cc3f73 100644
--- a/gnu/tests/databases.scm
+++ b/gnu/tests/databases.scm
@@ -215,7 +215,9 @@
 
 (define %postgresql-os
   (simple-operating-system
-   (service postgresql-service-type)))
+   (service postgresql-service-type
+            (postgresql-configuration
+             (postgresql postgresql-10)))))
 
 (define (run-postgresql-test)
   "Run tests in %POSTGRESQL-OS."
diff --git a/gnu/tests/guix.scm b/gnu/tests/guix.scm
index 20b67d55d32..af7d8f0b217 100644
--- a/gnu/tests/guix.scm
+++ b/gnu/tests/guix.scm
@@ -156,6 +156,7 @@
    (service dhcp-client-service-type)
    (service postgresql-service-type
             (postgresql-configuration
+             (postgresql postgresql-10)
              (config-file
               (postgresql-config-file
                (hba-file
diff --git a/gnu/tests/monitoring.scm b/gnu/tests/monitoring.scm
index 17b9edc3acc..7371b02fe14 100644
--- a/gnu/tests/monitoring.scm
+++ b/gnu/tests/monitoring.scm
@@ -307,7 +307,9 @@ zabbix||{}
   (let ((base-os
          (simple-operating-system
           (service dhcp-client-service-type)
-          (service postgresql-service-type)
+          (service postgresql-service-type
+                   (postgresql-configuration
+                    (postgresql postgresql-10)))
           (service zabbix-front-end-service-type
                    (zabbix-front-end-configuration
                     (db-password "zabbix")))
diff --git a/gnu/tests/web.scm b/gnu/tests/web.scm
index 7513eab2e49..7f4518acd23 100644
--- a/gnu/tests/web.scm
+++ b/gnu/tests/web.scm
@@ -567,7 +567,9 @@ HTTP-PORT."
              (config
               (httpd-config-file
                (listen '("8080"))))))
-   (service postgresql-service-type)
+   (service postgresql-service-type
+            (postgresql-configuration
+             (postgresql postgresql-10)))
    (service patchwork-service-type
             (patchwork-configuration
              (patchwork patchwork)