[get local ip with golang]

get_local_ip.go

package main

import (
        "net"
        "fmt"
      )

func GetLocalIP() (ipv4 string, err error) {
  var (
    addrs []net.Addr
    addr net.Addr
    ipNet *net.IPNet
    ok bool
  )
  
  if addrs, err = net.InterfaceAddrs(); err != nil {
      return
  }
  //get the netcard except lo
  for _, addr = range addrs {
    //type assert
    if ipNet, ok = addr.(*net.IPNet); ok && !ipNet.IP.IsLoopback() {
      if ipNet.IP.To4() != nil {
        ipv4 = ipNet.IP.String()
        return
      }
    }
  }
  return
}

func main() {
  var (
    local_ip string
    err error
  )
  if local_ip, err = GetLocalIP(); err != nil {
    return
  }
  fmt.Println("Local IP is %s", local_ip)
}