fix(repo): accept gzip-compressed index.yaml responses

Signed-off-by: vigneshakaviki <kumarvignesh295@gmail.com>

pkg/getter/httpgetter.go

@@ -17,6 +17,7 @@ package getter
 
 import (
 	"bytes"
+	"compress/gzip"
 	"context"
 	"crypto/tls"
 	"fmt"
@@ -24,6 +25,7 @@ import (
 	"log/slog"
 	"net/http"
 	"net/url"
+	"strings"
 	"sync"
 
 	"helm.sh/helm/v4/internal/tlsutil"
@@ -58,6 +60,10 @@ func (g *HTTPGetter) get(href string, opts getterOptions) (*bytes.Buffer, error)
 	if opts.acceptHeader != "" {
 		req.Header.Set("Accept", opts.acceptHeader)
 	}
+	acceptCompressedIndex := strings.HasSuffix(req.URL.Path, "/index.yaml")
+	if acceptCompressedIndex {
+		req.Header.Set("Accept-Encoding", "gzip")
+	}
 
 	req.Header.Set("User-Agent", version.GetUserAgent())
 	if opts.userAgent != "" {
@@ -101,7 +107,16 @@ func (g *HTTPGetter) get(href string, opts getterOptions) (*bytes.Buffer, error)
 	}
 
 	buf := bytes.NewBuffer(nil)
-	_, err = io.Copy(buf, resp.Body)
+	body := io.Reader(resp.Body)
+	if acceptCompressedIndex && resp.Header.Get("Content-Encoding") == "gzip" {
+		gz, err := gzip.NewReader(resp.Body)
+		if err != nil {
+			return nil, err
+		}
+		defer gz.Close()
+		body = gz
+	}
+	_, err = io.Copy(buf, body)
 	return buf, err
 }
 

pkg/repo/v1/index_test.go

@@ -19,6 +19,7 @@ package repo
 import (
 	"bufio"
 	"bytes"
+	"compress/gzip"
 	"encoding/json"
 	"errors"
 	"net/http"
@@ -289,6 +290,28 @@ func TestDownloadIndexFile(t *testing.T) {
 		require.NoErrorf(t, err, "error reading charts file")
 		verifyLocalChartsFile(t, b, i)
 	})
+
+	t.Run("should accept gzip-compressed index responses", func(t *testing.T) {
+		fileBytes, err := os.ReadFile(testfile)
+		require.NoError(t, err)
+		srv, err := startLocalServerForTests(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			assert.Equal(t, "gzip", r.Header.Get("Accept-Encoding"))
+			w.Header().Set("Content-Encoding", "gzip")
+			gz := gzip.NewWriter(w)
+			_, _ = gz.Write(fileBytes)
+			_ = gz.Close()
+		}))
+		require.NoError(t, err)
+		defer srv.Close()
+
+		r, err := NewChartRepository(&Entry{Name: testRepo, URL: srv.URL}, getter.All(&cli.EnvSettings{}))
+		require.NoError(t, err)
+		idx, err := r.DownloadIndexFile()
+		require.NoError(t, err)
+		i, err := LoadIndexFile(idx)
+		require.NoError(t, err)
+		verifyLocalIndex(t, i)
+	})
 }
 
 func verifyLocalIndex(t *testing.T, i *IndexFile) {