Go program to compress list of files into Zip file

package main
 
import (
	"archive/zip"
	"fmt"
	"io"
	"log"
	"os"
)
 
func appendFiles(filename string, zipw *zip.Writer) error {
	file, err := os.Open(filename)
	if err != nil {
		return fmt.Errorf("Failed to open %s: %s", filename, err)
	}
	defer file.Close()
 
	wr, err := zipw.Create(filename)
	if err != nil {
		msg := "Failed to create entry for %s in zip file: %s"
		return fmt.Errorf(msg, filename, err)
	}
 
	if _, err := io.Copy(wr, file); err != nil {
		return fmt.Errorf("Failed to write %s to zip: %s", filename, err)
	}
 
	return nil
}
 
func main() {
	flags := os.O_WRONLY | os.O_CREATE | os.O_TRUNC
	file, err := os.OpenFile("test.zip", flags, 0644)
	if err != nil {
		log.Fatalf("Failed to open zip for writing: %s", err)
	}
	defer file.Close()
 
	var files = []string{"test1.txt", "test2.txt", "test3.txt"}
 
	zipw := zip.NewWriter(file)
	defer zipw.Close()
 
	for _, filename := range files {
		if err := appendFiles(filename, zipw); err != nil {
			log.Fatalf("Failed to add file %s to zip: %s", filename, err)
		}
	}
}