feat: add gitlab source for gitlab package registry

cleanup http source

pkg/utils.go

@@ -3,8 +3,16 @@ package pkg
 import (
 	"archive/tar"
 	"compress/gzip"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"github.com/fatih/color"
+	"github.com/pkg/errors"
 	"io"
+	"io/ioutil"
+	"net/http"
 	"os"
+	"path"
 	"path/filepath"
 	"strings"
 )
@@ -91,3 +99,64 @@ func GzipUntar(dst string, r io.Reader, subDir string) error {
 		}
 	}
 }
+
+func CreateTempDir(name, dir, version string) (string, error) {
+	pkgh := sha256.Sum256([]byte(fmt.Sprintf("jsonnetpkg-%s-%s", strings.Replace(name, "/", "-", -1), strings.Replace(version, "/", "-", -1))))
+	// using 16 bytes should be a good middle ground between length and collision resistance
+	tmpDir, err := ioutil.TempDir(filepath.Join(dir, ".tmp"), hex.EncodeToString(pkgh[:16]))
+	if err != nil {
+		return "", errors.Wrap(err, "failed to create tmp dir")
+	}
+
+	return tmpDir, nil
+}
+
+func DownloadFile(filepath string, url string) error {
+	resp, err := http.Get(url)
+	if err != nil {
+		return err
+	}
+
+	color.Cyan("GET %s %d", url, resp.StatusCode)
+
+	if resp.StatusCode != 200 {
+		return fmt.Errorf("unexpected status code %d", resp.StatusCode)
+	}
+
+	defer resp.Body.Close()
+
+	// Create the file
+	out, err := os.Create(filepath)
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+
+	// Write the body to file
+	_, err = io.Copy(out, resp.Body)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func DownloadAndUntarTo(tmpDir, url, destPath string) error {
+	filename := filepath.Base(url)
+	err := DownloadFile(path.Join(tmpDir, filename), url)
+	if err != nil {
+		return errors.Wrap(err, "failed to download file")
+	}
+
+	var ar *os.File
+	ar, err = os.Open(path.Join(tmpDir, filename))
+	if err != nil {
+		return errors.Wrap(err, "failed to open downloaded archive")
+	}
+	defer ar.Close()
+	err = GzipUntar(destPath, ar, "")
+	if err != nil {
+		return errors.Wrap(err, "failed to unpack downloaded archive")
+	}
+	return nil
+}