func configureIface(ifname string, ipn ip.IP4Net, mtu int) error { iface, err := netlink.LinkByName(ifname) if err != nil { return fmt.Errorf("failed to lookup interface %v", ifname) } err = netlink.AddrAdd(iface, &netlink.Addr{ipn.ToIPNet(), ""}) if err != nil { return fmt.Errorf("failed to add IP address %v to %v: %v", ipn.String(), ifname, err) } err = netlink.LinkSetMTU(iface, mtu) if err != nil { return fmt.Errorf("failed to set MTU for %v: %v", ifname, err) } err = netlink.LinkSetUp(iface) if err != nil { return fmt.Errorf("failed to set interface %v to UP state: %v", ifname, err) } // explicitly add a route since there might be a route for a subnet already // installed by Docker and then it won't get auto added err = netlink.RouteAdd(&netlink.Route{ LinkIndex: iface.Attrs().Index, Scope: netlink.SCOPE_UNIVERSE, Dst: ipn.Network().ToIPNet(), }) if err != nil && err != syscall.EEXIST { return fmt.Errorf("Failed to add route (%v -> %v): %v", ipn.Network().String(), ifname, err) } return nil }