Add routes propagation for VRF plugin

Up until now, if previous plugin assigned routes to interface, movement of
this interface to new VRF cause routes to be deleted.

This patch adds funtionality to VRF plugin to save the routes before
interface is assgined to VRF, and then re-apply all saved routes to new VRF.

Signed-off-by: Artur Korzeniewski <artur.korzeniewski@travelping.com>

plugins/meta/vrf/vrf.go

@@ -104,6 +104,19 @@ func addInterface(vrf *netlink.Vrf, intf string) error {
 	if err != nil {
 		return fmt.Errorf("failed getting ipv6 addresses for %s", intf)
 	}
+
+	// Save all routes that are not local and connected, before setting master,
+	// because otherwise those routes will be deleted after interface is moved.
+	filter := &netlink.Route{
+		LinkIndex: i.Attrs().Index,
+		Scope:     netlink.SCOPE_UNIVERSE, // Exclude local and connected routes
+	}
+	filterMask := netlink.RT_FILTER_IIF | netlink.RT_FILTER_SCOPE // Filter based on link index and scope
+	routes, err := netlink.RouteListFiltered(netlink.FAMILY_ALL, filter, filterMask)
+	if err != nil {
+		return fmt.Errorf("failed getting all routes for %s", intf)
+	}
+
 	err = netlink.LinkSetMaster(i, vrf)
 	if err != nil {
 		return fmt.Errorf("could not set vrf %s as master of %s: %v", vrf.Name, intf, err)
@@ -130,6 +143,18 @@ CONTINUE:
 		}
 	}
 
+	// Apply all saved routes for the interface that was moved to the VRF
+	for _, route := range routes {
+		r := route
+		// Modify original table to vrf one,
+		r.Table = int(vrf.Table)
+		// equivalent of 'ip route replace <address> table <int>'.
+		err = netlink.RouteReplace(&r)
+		if err != nil {
+			return fmt.Errorf("could not add route '%s': %v", r, err)
+		}
+	}
+
 	return nil
 }