system: T5877: Shorten system domain-search config path

Shorten and simplify `system domain-search` config path from:
```
set system domain-search domain <domain1>
```
to:
```
set system domain-search <domain1>
```

This will shorten the path and also make consistent with `domain-search`
config in other places (like `dhcp-server`).

(cherry picked from commit f77bf573c608b6c09182e1bad4312c4dd1e5195e)

4 files changed, 58 insertions, 17 deletions

diff --git a/interface-definitions/dns-domain-name.xml.in b/interface-definitions/dns-domain-name.xml.in
index ef34ecbf5..b5b3692b1 100644
--- a/interface-definitions/dns-domain-name.xml.in
+++ b/interface-definitions/dns-domain-name.xml.in
@@ -45,24 +45,17 @@
           </constraint>
         </properties>
       </leafNode>
-      <node name="domain-search" owner="${vyos_conf_scripts_dir}/host_name.py">
+      <leafNode name="domain-search" owner="${vyos_conf_scripts_dir}/host_name.py">
         <properties>
           <help>Domain Name Server (DNS) domain completion order</help>
           <priority>400</priority>
+          <constraint>
+            <validator name="fqdn"/>
+          </constraint>
+          <constraintErrorMessage>Invalid domain name (RFC 1123 section 2).\nMay only contain letters, numbers and period.</constraintErrorMessage>
+          <multi/>
         </properties>
-        <children>
-          <leafNode name="domain">
-            <properties>
-              <help>DNS domain completion order</help>
-              <constraint>
-                <regex>[-a-zA-Z0-9.]+</regex>
-              </constraint>
-              <constraintErrorMessage>Invalid domain name</constraintErrorMessage>
-              <multi/>
-            </properties>
-          </leafNode>
-        </children>
-      </node>
+      </leafNode>
       <node name="static-host-mapping" owner="${vyos_conf_scripts_dir}/host_name.py">
         <properties>
           <help>Map host names to addresses</help>
diff --git a/interface-definitions/include/version/system-version.xml.i b/interface-definitions/include/version/system-version.xml.i
index 73df8bd8e..fcb24abe2 100644
--- a/interface-definitions/include/version/system-version.xml.i
+++ b/interface-definitions/include/version/system-version.xml.i
@@ -1,3 +1,3 @@
 <!-- include start from include/version/system-version.xml.i -->
-<syntaxVersion component='system' version='26'></syntaxVersion>
+<syntaxVersion component='system' version='27'></syntaxVersion>
 <!-- include end -->
diff --git a/src/conf_mode/host_name.py b/src/conf_mode/host_name.py
index 36d1f6493..6204cf247 100755
--- a/src/conf_mode/host_name.py
+++ b/src/conf_mode/host_name.py
@@ -61,8 +61,9 @@ def get_config(config=None):
         hosts['domain_name'] = conf.return_value(['system', 'domain-name'])
         hosts['domain_search'].append(hosts['domain_name'])
 
-    for search in conf.return_values(['system', 'domain-search', 'domain']):
-        hosts['domain_search'].append(search)
+    if conf.exists(['system', 'domain-search']):
+        for search in conf.return_values(['system', 'domain-search']):
+            hosts['domain_search'].append(search)
 
     if conf.exists(['system', 'name-server']):
         for ns in conf.return_values(['system', 'name-server']):
diff --git a/src/migration-scripts/system/26-to-27 b/src/migration-scripts/system/26-to-27
new file mode 100755
index 000000000..80bb82cbd
--- /dev/null
+++ b/src/migration-scripts/system/26-to-27
@@ -0,0 +1,47 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2023 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# T5877: migrate 'system domain-search domain' to 'system domain-search'
+
+from sys import exit, argv
+from vyos.configtree import ConfigTree
+
+if len(argv) < 2:
+    print("Must specify file name!")
+    exit(1)
+
+file_name = argv[1]
+with open(file_name, 'r') as f:
+    config_file = f.read()
+
+base = ['system', 'domain-search']
+config = ConfigTree(config_file)
+
+if not config.exists(base):
+    exit(0)
+
+if config.exists(base + ['domain']):
+    entries = config.return_values(base + ['domain'])
+    config.delete(base + ['domain'])
+    for entry in entries:
+        config.set(base, value=entry, replace=False)
+
+try:
+    with open(file_name, 'w') as f:
+        f.write(config.to_string())
+except OSError as e:
+    print(f'Failed to save the modified config: {e}')
+    exit(1)