func getNodeIP()

in internal/node/hybrid/ip_validator.go [144:189]

• 28 lines of code
• 12 McCabe index (conditional complexity)

func getNodeIP(kubeletArgs []string, nodeName string, network Network) (net.IP, error) {
	// Follows algorithm used by kubelet to assign nodeIP
	// Implementation adapted for hybrid nodes
	// 1) Use nodeIP if set (and not "0.0.0.0"/"::")
	// 2) If the user has specified an IP to HostnameOverride, use it (not allowed for hybrid nodes)
	// 3) Lookup the IP from node name by DNS
	// 4) Try to get the IP from the network interface used as default gateway
	// Source: https://github.com/kubernetes/kubernetes/blob/master/pkg/kubelet/nodestatus/setters.go#L206

	nodeIP, err := extractNodeIPFromFlags(kubeletArgs)
	if err != nil {
		return nil, err
	}

	var ipAddr net.IP

	nodeIPSpecified := nodeIP != nil && nodeIP.To4() != nil && !nodeIP.IsUnspecified()

	if nodeIPSpecified {
		ipAddr = nodeIP
	} else {
		// If using SSM, the node name will be set at initialization to the SSM instance ID,
		// so it won't resolve to anything via DNS, hence we're only checking in the case of IAM-RA
		if nodeName != "" {
			addrs, _ := network.LookupIP(nodeName)
			for _, addr := range addrs {
				if err = validateNodeIP(addr, network.InterfaceAddrs); addr.To4() != nil && err == nil {
					ipAddr = addr
					break
				}
			}
		}

		if ipAddr == nil {
			ipAddr, err = network.ResolveBindAddress(nodeIP)
		}

		if err != nil || ipAddr == nil {
			// We tried everything we could, but the IP address wasn't fetchable; error out
			return nil, fmt.Errorf("couldn't get ip address of node: %w", err)
		}

	}

	return ipAddr, nil
}