package netutil import ( "fmt" "net" "github.com/pkg/errors" "github.com/sirupsen/logrus" ) func GetIPFromInterface(ifaceName string) string { ip, err := getIPFromInterface(ifaceName) if err != nil { logrus.Warn(errors.Wrap(err, "unable to get global unicast ip from interface name")) } else { logrus.Infof("Found ip %s from iface %s", ip, ifaceName) } return ip } func getIPFromInterface(ifaceName string) (string, error) { iface, err := net.InterfaceByName(ifaceName) if err != nil { return "", err } addrs, err := iface.Addrs() if err != nil { return "", err } if iface.Flags&net.FlagUp == 0 { return "", fmt.Errorf("the interface %s is not up", ifaceName) } globalUnicasts := []string{} for _, addr := range addrs { ip, _, err := net.ParseCIDR(addr.String()) if err != nil { return "", errors.Wrapf(err, "unable to parse CIDR for interface %s", iface.Name) } // skipping if not ipv4 if ip.To4() == nil { continue } if ip.IsGlobalUnicast() { globalUnicasts = append(globalUnicasts, ip.String()) } } if len(globalUnicasts) > 1 { return "", fmt.Errorf("multiple global unicast addresses defined for %s, please set ip from one of %v", ifaceName, globalUnicasts) } if len(globalUnicasts) == 1 { return globalUnicasts[0], nil } return "", fmt.Errorf("can't find ip for interface %s", ifaceName) }