Accept `gzip` for fetching a repository index file.

The change introduces a new `getter` option - `enableCompression`, and enables the feature for downloading a repository index file.

When the option value is `true`:
- `HttpGetter` adds "Accept-Encoding: gzip" header to a request.
- `HttpGetter` performs decompression of a response body if the response contains "Content-Encoding: gzip" header.

Signed-off-by: Alex Prizov <prizov@me.com>

pkg/getter/getter.go

@@ -42,6 +42,7 @@ type options struct {
 	passCredentialsAll    bool
 	userAgent             string
 	version               string
+	enableCompression     bool
 	registryClient        *registry.Client
 	timeout               time.Duration
 	transport             *http.Transport
@@ -115,6 +116,13 @@ func WithRegistryClient(client *registry.Client) Option {
 	}
 }
 
+// WithCompression enables compression
+func WithCompression() Option {
+	return func(opts *options) {
+		opts.enableCompression = true
+	}
+}
+
 func WithUntar() Option {
 	return func(opts *options) {
 		opts.unTar = true

pkg/getter/httpgetter.go

@@ -17,6 +17,7 @@ package getter
 
 import (
 	"bytes"
+	"compress/gzip"
 	"crypto/tls"
 	"io"
 	"net/http"
@@ -78,6 +79,10 @@ func (g *HTTPGetter) get(href string) (*bytes.Buffer, error) {
 		}
 	}
 
+	if g.opts.enableCompression {
+		req.Header.Add("Accept-Encoding", "gzip")
+	}
+
 	client, err := g.httpClient()
 	if err != nil {
 		return nil, err
@@ -93,7 +98,19 @@ func (g *HTTPGetter) get(href string) (*bytes.Buffer, error) {
 	}
 
 	buf := bytes.NewBuffer(nil)
-	_, err = io.Copy(buf, resp.Body)
+
+	body := resp.Body
+
+	if g.opts.enableCompression && resp.Header.Get("Content-Encoding") == "gzip" {
+		body, err = gzip.NewReader(resp.Body)
+		if err != nil {
+			return nil, err
+		}
+		defer body.Close()
+	}
+
+	_, err = io.Copy(buf, body)
+
 	return buf, err
 }
 

pkg/getter/httpgetter_test.go

@@ -16,6 +16,8 @@ limitations under the License.
 package getter
 
 import (
+	"bytes"
+	"compress/gzip"
 	"fmt"
 	"io"
 	"net/http"
@@ -363,6 +365,30 @@ func TestDownloadInsecureSkipTLSVerify(t *testing.T) {
 
 }
 
+func TestHTTPGetterWithCompression(t *testing.T) {
+	expectedData := []byte("index.yaml")
+
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Encoding", "gzip")
+		gzipWriter := gzip.NewWriter(w)
+		gzipWriter.Write(expectedData)
+		gzipWriter.Close()
+	}))
+
+	defer srv.Close()
+
+	g, err := NewHTTPGetter(WithURL(srv.URL), WithCompression())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	data, _ := g.Get(srv.URL)
+
+	if bytes.Compare(data.Bytes(), expectedData) != 0 {
+		t.Fatalf("Expected response with uncompressed data %s, but got %s", expectedData, data.Bytes())
+	}
+}
+
 func TestHTTPGetterTarDownload(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		f, _ := os.Open("testdata/empty-0.0.1.tgz")

pkg/repo/chartrepo.go

@@ -131,6 +131,7 @@ func (r *ChartRepository) DownloadIndexFile() (string, error) {
 		getter.WithTLSClientConfig(r.Config.CertFile, r.Config.KeyFile, r.Config.CAFile),
 		getter.WithBasicAuth(r.Config.Username, r.Config.Password),
 		getter.WithPassCredentialsAll(r.Config.PassCredentialsAll),
+		getter.WithCompression(),
 	)
 	if err != nil {
 		return "", err