isis: T8094: bugfix config migration from 1.3.0-rc1 -> 1.4

While producing all configtest assert files for VyOS 1.4 it was noted that
the the isis-small testcase from fails. This config fragment is not properly
migrated when updating from VyOS 1.3.0-rc1 -> 1.4 and using IS-IS.

protocols {
    isis FOO {
        interface eth1 {
           bfd
        }
        net 49.0001.1921.6800.1002.00
        redistribute {
            ipv4 {
                connected {
                    level-2 {
                        route-map EXPORT-ISIS
                    }
                }
            }
        }
    }
}

and results in loosing IS-IS connectivity. This is due the fact that
config.rename() does not work when only using the base tagNode.

2 files changed, 17 insertions, 9 deletions

diff --git a/smoketest/configs/isis-small b/smoketest/configs/isis-small
index 79a2f042f..b93a18549 100644
--- a/smoketest/configs/isis-small
+++ b/smoketest/configs/isis-small
@@ -57,7 +57,7 @@ policy {
     }
 }
 protocols {
-    isis {
+    isis FOO {
         interface eth1 {
             bfd
         }
@@ -126,5 +126,5 @@ system {
 
 
 // Warning: Do not remove the following line.
-// vyos-config-version: "broadcast-relay@1:cluster@1:config-management@1:conntrack@3:conntrack-sync@2:dhcp-relay@2:dhcp-server@6:dhcpv6-server@1:dns-forwarding@3:firewall@5:https@2:interfaces@22:ipoe-server@1:ipsec@5:isis@1:l2tp@3:lldp@1:mdns@1:nat@5:ntp@1:pppoe-server@5:pptp@2:qos@1:quagga@8:rpki@1:salt@1:snmp@2:ssh@2:sstp@3:system@21:vrrp@2:vyos-accel-ppp@2:wanloadbalance@3:webproxy@2:zone-policy@1"
-// Release version: 1.3.0
+// vyos-config-version: "broadcast-relay@1:cluster@1:config-management@1:conntrack@1:conntrack-sync@1:dhcp-relay@2:dhcp-server@5:dhcpv6-server@1:dns-forwarding@3:firewall@5:https@2:interfaces@18:ipoe-server@1:ipsec@5:l2tp@3:lldp@1:mdns@1:nat@5:ntp@1:pppoe-server@5:pptp@2:qos@1:quagga@7:rpki@1:salt@1:snmp@2:ssh@2:sstp@3:system@20:vrrp@2:vyos-accel-ppp@2:wanloadbalance@3:webproxy@2:zone-policy@1"
+// Release version: 1.3.0-rc1
diff --git a/src/migration-scripts/isis/0-to-1 b/src/migration-scripts/isis/0-to-1
index 052dbc8a8..3a9735d29 100644
--- a/src/migration-scripts/isis/0-to-1
+++ b/src/migration-scripts/isis/0-to-1
@@ -24,13 +24,21 @@ def migrate(config: ConfigTree) -> None:
         # Nothing to do
         return
 
-    # We need a temporary copy of the config
-    tmp_base = ['protocols', 'isis2']
-    config.copy(base, tmp_base)
+    if not config.is_tag(base):
+        # Nothing to do
+        exit(0)
+
+    # Get IS-IS domain ID
+    domain_id = config.list_nodes(base)
+    if domain_id:
+        # We need a temporary copy of the config
+        tmp_base = ['protocols', 'isis2']
+        config.copy(base + domain_id, tmp_base)
 
     # Now it's save to delete the old configuration
     config.delete(base)
 
-    # Rename temporary copy to new final config (IS-IS domain key is static and no
-    # longer required to be set via CLI)
-    config.rename(tmp_base, 'isis')
+    # Rename temporary node to new final config (IS-IS domain key is static and
+    # no longer required to be set via CLI)
+    if config.exists(tmp_base):
+        config.rename(tmp_base, 'isis')