name-server: T3804: merge "system name-servers-dhcp" into "system name-server"

We have "set system name-server <ipv4|ipv6>" to specify a name-server IP
address we wan't to use. We also have "set system name-servers-dhcp <interface>"
which does the same, but the name-server in question is retrieved via DHCP.

Both CLI nodes are combined under "set system name-server <ipv4|ipv6|interface>"
to keep things as they are in real life - we need a name-server.

(cherry picked from commit 2ecf7a9f9cbe9359457bd23b4a0c45f3763123c7)

1 files changed, 48 insertions, 0 deletions

diff --git a/src/migration-scripts/system/20-to-21 b/src/migration-scripts/system/20-to-21
new file mode 100755
index 000000000..1728995de
--- /dev/null
+++ b/src/migration-scripts/system/20-to-21
@@ -0,0 +1,48 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2021 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/>.
+
+# T3795: merge "system name-servers-dhcp" into "system name-server"
+
+import os
+
+from sys import argv
+from vyos.configtree import ConfigTree
+
+if (len(argv) < 1):
+    print("Must specify file name!")
+    exit(1)
+
+file_name = argv[1]
+with open(file_name, 'r') as f:
+    config_file = f.read()
+
+base = ['system', 'name-servers-dhcp']
+config = ConfigTree(config_file)
+if not config.exists(base):
+    # Nothing to do
+    exit(0)
+
+for interface in config.return_values(base):
+    config.set(['system', 'name-server'], value=interface, replace=False)
+
+config.delete(base)
+
+try:
+    with open(file_name, 'w') as f:
+        f.write(config.to_string())
+except OSError as e:
+    print("Failed to save the modified config: {}".format(e))
+    exit(1)