Introduce "NTP server" role

This makes IPA servers that publish their NTP services in LDAP searchable by
`server-role-find` and `server-find` command.

The list of active IPA NTP servers will be displayed in to output of `ipa
config-show` command.

https://fedorahosted.org/freeipa/ticket/5815

Reviewed-By: Petr Spacek <pspacek@redhat.com>
Reviewed-By: Martin Basti <mbasti@redhat.com>

ipaserver/plugins/config.py

@@ -239,6 +239,12 @@ class config(LDAPObject):
             doc=_('IPA servers configured as certificate authority'),
             flags={'virtual_attribute', 'no_create', 'no_update'}
         ),
+        Str(
+            'ntp_server_server*',
+            label=_('IPA NTP servers'),
+            doc=_('IPA servers with enabled NTP'),
+            flags={'virtual_attribute', 'no_create', 'no_update'}
+        ),
         Str(
             'ca_renewal_master_server?',
             label=_('IPA CA renewal master'),
@@ -256,11 +262,9 @@ class config(LDAPObject):
 
         backend = self.api.Backend.serverroles
 
-        ca_config = backend.config_retrieve("CA server")
-        master_config = backend.config_retrieve("IPA master")
-
-        entry_attrs.update(ca_config)
-        entry_attrs.update(master_config)
+        for role in ("CA server", "IPA master", "NTP server"):
+            config = backend.config_retrieve(role)
+            entry_attrs.update(config)
 
 
 @register()

ipaserver/servroles.py

@@ -566,6 +566,11 @@ role_instances = (
         u"KRA server",
         component_services=['KRA']
     ),
+    ServiceBasedRole(
+        u"ntp_server_server",
+        u"NTP server",
+        component_services=['NTP']
+    )
 )
 
 attribute_instances = (