builder/common: Error on non-200 download responses [GH-141]

CHANGELOG.md

@@ -14,6 +14,8 @@ IMPROVEMENTS:
 
 BUG FIXES:
 
+* core: Non-200 response codes on downloads now show proper errors.
+  [GH-141]
 * vagrant: The `BuildName` template propery works properly in
   the output path.
 * vagrant: Properly configure the provider-specific post-processors so

builder/common/download.go

@@ -107,6 +107,9 @@ func (d *DownloadClient) Get() (string, error) {
 
 		log.Printf("Downloading: %s", url.String())
 		err = d.downloader.Download(f, url)
+		if err != nil {
+			return "", err
+		}
 	}
 
 	if d.config.Hash != nil {
@@ -160,11 +163,22 @@ func (*HTTPDownloader) Cancel() {
 }
 
 func (d *HTTPDownloader) Download(dst io.Writer, src *url.URL) error {
+	log.Printf("Starting download: %s", src.String())
 	resp, err := http.Get(src.String())
 	if err != nil {
 		return err
 	}
 
+	if resp.StatusCode != 200 {
+		log.Printf(
+			"Non-200 status code: %d. Getting error body.", resp.StatusCode)
+
+		errorBody := new(bytes.Buffer)
+		io.Copy(errorBody, resp.Body)
+		return fmt.Errorf("HTTP error '%d'! Remote side responded:\n%s",
+			resp.StatusCode, errorBody.String())
+	}
+
 	d.progress = 0
 	d.total = uint(resp.ContentLength)