bgp: T1711: remove ASN tagNode and move to "local-as"

Every time when set configuration bgp, you need set AS number. There is very
less benefit in this system so the AS number is moved from a tagNode level down
to a leafNode with the name "local-as", same as on the neighbor or peer-group
level.

This changes the CLI configuration from:

set protocols bgp 100 neighbor 10.10.1.2 remote-as 200

to

set protocols bgp local-as 100
set protocols bgp neighbor 10.10.1.2 remote-as 200

1 files changed, 61 insertions, 0 deletions

diff --git a/src/migration-scripts/bgp/0-to-1 b/src/migration-scripts/bgp/0-to-1
new file mode 100755
index 000000000..a70b52909
--- /dev/null
+++ b/src/migration-scripts/bgp/0-to-1
@@ -0,0 +1,61 @@
+#!/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/>.
+
+# T3417: migrate IS-IS tagNode to node as we can only have one IS-IS process
+
+from sys import argv
+from sys import exit
+
+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 = ['protocols', 'bgp']
+config = ConfigTree(config_file)
+
+if not config.exists(base):
+    # Nothing to do
+    exit(0)
+
+# Only one BGP process is supported, thus this operation is savea
+asn = config.list_nodes(base)
+bgp_base = base + asn
+print(asn)
+
+# We need a temporary copy of the config
+tmp_base = ['protocols', 'bgp2']
+config.copy(bgp_base, tmp_base)
+
+# Now it's save to delete the old configuration
+config.delete(base)
+
+# Rename temporary copy to new final config and set new "local-as" option
+config.rename(tmp_base, 'bgp')
+config.set(base + ['local-as'], value=asn[0])
+
+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)