github.com/weaveworks/common@v0.0.0-20230728070032-dd9e68f319d5/network/interface.go (about)

     1  package network
     2  
     3  import (
     4  	"fmt"
     5  	"net"
     6  )
     7  
     8  // GetFirstAddressOf returns the first IPv4 address of the supplied interface name.
     9  func GetFirstAddressOf(name string) (string, error) {
    10  	inf, err := net.InterfaceByName(name)
    11  	if err != nil {
    12  		return "", err
    13  	}
    14  
    15  	addrs, err := inf.Addrs()
    16  	if err != nil {
    17  		return "", err
    18  	}
    19  	if len(addrs) <= 0 {
    20  		return "", fmt.Errorf("No address found for %s", name)
    21  	}
    22  
    23  	for _, addr := range addrs {
    24  		switch v := addr.(type) {
    25  		case *net.IPNet:
    26  			if ip := v.IP.To4(); ip != nil {
    27  				return v.IP.String(), nil
    28  			}
    29  		}
    30  	}
    31  
    32  	return "", fmt.Errorf("No address found for %s", name)
    33  }