package docker import ( "archive/tar" "bytes" "io" ) func fakeTar() (io.Reader, error) { content := []byte("Hello world!\n") buf := new(bytes.Buffer) tw := tar.NewWriter(buf) for _, name := range []string{"/etc/postgres/postgres.conf", "/etc/passwd", "/var/log/postgres/postgres.conf"} { hdr := new(tar.Header) hdr.Size = int64(len(content)) hdr.Name = name if err := tw.WriteHeader(hdr); err != nil { return nil, err } tw.Write([]byte(content)) } tw.Close() return buf, nil }