Added --ignore-iface option to netcheck and use it to ignore weave bridge route

net/route.go

@@ -9,13 +9,17 @@ import (
 
 // A network is considered free if it does not overlap any existing
 // routes on this host. This is the same approach taken by Docker.
-func CheckNetworkFree(subnet *net.IPNet) error {
+func CheckNetworkFree(subnet *net.IPNet, ignoreIfName string) error {
 	routes, err := netlink.RouteList(nil, netlink.FAMILY_V4)
 	if err != nil {
 		return err
 	}
 	for _, route := range routes {
 		if route.Dst != nil && overlaps(route.Dst, subnet) {
+			if link, err := netlink.LinkByIndex(route.LinkIndex); err == nil && link.Attrs().Name == ignoreIfName {
+				continue
+			}
+
 			return fmt.Errorf("Network %s overlaps with existing route %s on host.", subnet, route.Dst)
 		}
 	}
@@ -29,13 +33,16 @@ func overlaps(n1, n2 *net.IPNet) bool {
 
 // For a specific address, we only care if it is actually *inside* an
 // existing route, because weave-local traffic never hits IP routing.
-func CheckAddressOverlap(addr net.IP) error {
+func CheckAddressOverlap(addr net.IP, ignoreIfName string) error {
 	routes, err := netlink.RouteList(nil, netlink.FAMILY_V4)
 	if err != nil {
 		return err
 	}
 	for _, route := range routes {
 		if route.Dst != nil && route.Dst.Contains(addr) {
+			if link, err := netlink.LinkByIndex(route.LinkIndex); err == nil && link.Attrs().Name == ignoreIfName {
+				continue
+			}
 			return fmt.Errorf("Address %s overlaps with existing route %s on host.", addr, route.Dst)
 		}
 	}