ValidateMTU: check only the interface that holds the node ip

The only interface that needs to be checked is the one tied to the node
ip. This prevents tainting the node when another interface is added with
a lower MTU.

Signed-off-by: Federico Paolinelli <fpaoline@redhat.com>

pkg/network/node/node.go

@@ -268,6 +268,19 @@ func (node *OsdnNode) validateMTU() error {
 			return fmt.Errorf("could not retrieve link id %d while validating MTU", route.LinkIndex)
 		}
 
+		// we want to check the mtu only for the interface assigned to the node's primary ip
+		found := false
+		addresses, err := netlink.AddrList(link, netlink.FAMILY_V4)
+		for _, address := range addresses {
+			if node.localIP == address.IP.String() {
+				found = true
+				break
+			}
+		}
+		if !found {
+			continue
+		}
+
 		newmtu := link.Attrs().MTU
 		if newmtu > 0 && newmtu < mtu {
 			mtu = newmtu