Added option to compress and archive multiple generated files

pkg/util/util.go

@@ -1,8 +1,10 @@
 package util
 
 import (
+	"archive/tar"
 	"bytes"
 	"cmp"
+	"compress/gzip"
 	"crypto/tls"
 	"fmt"
 	"io"
@@ -97,3 +99,64 @@ func CopyIf[T comparable](s []T, condition func(t T) bool) []T {
 	}
 	return f
 }
+
+func CreateArchive(files []string, buf io.Writer) error {
+	// Create new Writers for gzip and tar
+	// These writers are chained. Writing to the tar writer will
+	// write to the gzip writer which in turn will write to
+	// the "buf" writer
+	gw := gzip.NewWriter(buf)
+	defer gw.Close()
+	tw := tar.NewWriter(gw)
+	defer tw.Close()
+
+	// Iterate over files and add them to the tar archive
+	for _, file := range files {
+		err := addToArchive(tw, file)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func addToArchive(tw *tar.Writer, filename string) error {
+	// open file to write to archive
+	file, err := os.Open(filename)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	// get FileInfo for file size, mode, etc.
+	info, err := file.Stat()
+	if err != nil {
+		return err
+	}
+
+	// create a tar Header from the FileInfo data
+	header, err := tar.FileInfoHeader(info, info.Name())
+	if err != nil {
+		return err
+	}
+
+	// use full path as name (FileInfoHeader only takes the basename) to
+	// preserve directory structure
+	// see for more info: https://golang.org/src/archive/tar/common.go?#L626
+	header.Name = filename
+
+	// Write file header to the tar archive
+	err = tw.WriteHeader(header)
+	if err != nil {
+		return err
+	}
+
+	// copy file content to tar archive
+	_, err = io.Copy(tw, file)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}