go-kratos/kratos · error

failed to extract port: %v

Error message

failed to extract port: %v

What it means

Error "failed to extract port: %v" thrown in go-kratos/kratos.

Source

Thrown at internal/host/host.go:42

// Port return a real port.
func Port(lis net.Listener) (int, bool) {
	if addr, ok := lis.Addr().(*net.TCPAddr); ok {
		return addr.Port, true
	}
	return 0, false
}

// Extract returns a private addr and port.
func Extract(hostPort string, lis net.Listener) (string, error) {
	addr, port, err := net.SplitHostPort(hostPort)
	if err != nil && lis == nil {
		return "", err
	}
	if lis != nil {
		p, ok := Port(lis)
		if !ok {
			return "", fmt.Errorf("failed to extract port: %v", lis.Addr())
		}
		port = strconv.Itoa(p)
	}
	if len(addr) > 0 && (addr != "0.0.0.0" && addr != "[::]" && addr != "::") {
		return net.JoinHostPort(addr, port), nil
	}
	ifaces, err := net.Interfaces()
	if err != nil {
		return "", err
	}
	var (
		minIndex = 0
		ips      = make([]net.IP, 0, 1)
	)
	for _, iface := range ifaces {
		if iface.Flags&net.FlagUp == 0 {
			continue
		}

View on GitHub (pinned to 668db92c2c)

When it happens

Trigger: Thrown at internal/host/host.go:42 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of go-kratos/kratos@668db92c2c (2026-08-16). Data as JSON: /api/errors/d249e62edcd312e3. Report an issue: GitHub.