get local and external ip address in golang

package ip

import (
    "fmt"
    "io/ioutil"
    "net"
    "net/http"
    "testing"
)

func TestGetLocalIP(t *testing.T) {
    addrs,_ := getLocalIP()
    for _, a := range addrs{
        fmt.Println(a)
    }
// 172.19.208.108
// 172.19.198.50
}

func TestGetOutboundIP(t *testing.T) {
    ip, _ := getOutboundIP()
    fmt.Println(ip)
// 172.19.198.50
}

func TestGetExternalIP(t *testing.T) {
    ip, _ := getPublicIP()
    fmt.Println(ip)
// 69.172.92.94
}

// getLocalIP get all your local ipv4 address (except 127.0.0.1)
func getLocalIP() ([]string, error) {
    addrs, err := net.InterfaceAddrs()
    if err != nil {
        return nil, err
    }
    IPs := make([]string, 0)
    for _, a := range addrs {
        if ipNet, ok := a.(*net.IPNet); ok && !ipNet.IP.IsLoopback() {
            if ipNet.IP.To4() != nil {
                IPs = append(IPs, ipNet.IP.To4().String())
            }
        }
    }
    return IPs, nil
}

// getOutboundIP get the out bound ip, especially useful when you have multi local ipv4 ip and you want figure out which one is been used
func getOutboundIP() (string, error) {
    conn, err := net.Dial("udp", "8.8.8.8:80")
    //conn, err := net.Dial("udp", "114.114.114.114:80")
    if err != nil {
        return "", err
    }
    defer conn.Close()
    localAddr := conn.LocalAddr().(*net.UDPAddr)
    return localAddr.IP.String(), nil
}

// getPublicIP get your publilc ip
func getPublicIP() (string, error) {
    resp, err := http.Get("https://ifconfig.me")
    if err != nil {
        return "", err
    }
    defer resp.Body.Close()
    body, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        return "", err
    }
    return string(body), nil
}