Send HTTP request with X509 auth golang

send_request.go

package main

import (
	"crypto/tls"
	"io"
	"log"
	"net/http"
	"os"
)

func main() {
	if len(os.Args) != 2 {
		log.Fatal("Please specify filename")
		return
	}
	// Load client cert
	cert, err := tls.LoadX509KeyPair("main.cert", "main.key")
	if err != nil {
		log.Fatal(err)
	}

	// Setup HTTPS client
	tlsConfig := &tls.Config{
		Certificates: []tls.Certificate{cert},
	}
	tlsConfig.BuildNameToCertificate()
	transport := &http.Transport{TLSClientConfig: tlsConfig}
	client := &http.Client{Transport: transport}

	fileName := os.Args[1]
	f, err := os.Open(fileName)
	if err != nil {
		log.Fatalln(err)
		return
	}
	
	req, err := http.NewRequest("POST", "https://some_domain.com/xml", f)
	req.Header.Add("Content-Type", "text/xml;charset=UTF-8")
	resp, err := client.Do(req)
	if err != nil {
		panic(err)
	}

	defer resp.Body.Close()
	_, err = io.Copy(os.Stdout, resp.Body)
	if err != nil {
		log.Fatal(err)
	}

}