Always request querier to return gzipped response (#4960)

* Always request querier to return gzipped response

Signed-off-by: Alan Protasio <[email protected]>

* make lint happy

Signed-off-by: Alan Protasio <[email protected]>

Signed-off-by: Alan Protasio <[email protected]>

Author: alanprot

CHANGELOG.md

@@ -75,6 +75,7 @@
 * [BUGFIX] AlertManager: fixed issue introduced by #4495 where templates files were being deleted when using alertmanager local store. #4890
 * [BUGFIX] Ingester: fixed incorrect logging at the start of ingester block shipping logic. #4934
 * [BUGFIX] Storage/Bucket: fixed global mark missing on deletion. #4949
+* [BUGFIX] QueryFrontend/Querier: fixed regression added by #4863 where we stopped compressing the response between querier and query frontend. #4960
 
 ## 1.13.0 2022-07-14
 

pkg/querier/tripperware/instantquery/instant_query.go

@@ -203,6 +203,9 @@ func (instantQueryCodec) EncodeRequest(ctx context.Context, r tripperware.Reques
 		}
 	}
 
+	// Always ask gzip to the querier
+	h.Set("Accept-Encoding", "gzip")
+
 	req := &http.Request{
 		Method:     "GET",
 		RequestURI: u.String(), // This is what the httpgrpc code looks at.

pkg/querier/tripperware/query.go

@@ -2,11 +2,14 @@ package tripperware
 
 import (
 	"bytes"
+	"compress/gzip"
 	"context"
 	"encoding/json"
+	"io"
 	"net/http"
 	"sort"
 	"strconv"
+	"strings"
 	"time"
 	"unsafe"
 
@@ -146,19 +149,34 @@ type Buffer interface {
 }
 
 func BodyBuffer(res *http.Response) ([]byte, error) {
+	var buf *bytes.Buffer
+
 	// Attempt to cast the response body to a Buffer and use it if possible.
 	// This is because the frontend may have already read the body and buffered it.
 	if buffer, ok := res.Body.(Buffer); ok {
-		return buffer.Bytes(), nil
+		buf = bytes.NewBuffer(buffer.Bytes())
+	} else {
+		// Preallocate the buffer with the exact size so we don't waste allocations
+		// while progressively growing an initial small buffer. The buffer capacity
+		// is increased by MinRead to avoid extra allocations due to how ReadFrom()
+		// internally works.
+		buf = bytes.NewBuffer(make([]byte, 0, res.ContentLength+bytes.MinRead))
+		if _, err := buf.ReadFrom(res.Body); err != nil {
+			return nil, httpgrpc.Errorf(http.StatusInternalServerError, "error decoding response: %v", err)
+		}
 	}
-	// Preallocate the buffer with the exact size so we don't waste allocations
-	// while progressively growing an initial small buffer. The buffer capacity
-	// is increased by MinRead to avoid extra allocations due to how ReadFrom()
-	// internally works.
-	buf := bytes.NewBuffer(make([]byte, 0, res.ContentLength+bytes.MinRead))
-	if _, err := buf.ReadFrom(res.Body); err != nil {
-		return nil, httpgrpc.Errorf(http.StatusInternalServerError, "error decoding response: %v", err)
+
+	// if the response is gziped, lets unzip it here
+	if strings.EqualFold(res.Header.Get("Content-Encoding"), "gzip") {
+		gReader, err := gzip.NewReader(buf)
+
+		if err != nil {
+			return nil, err
+		}
+
+		return io.ReadAll(gReader)
 	}
+
 	return buf.Bytes(), nil
 }
 

pkg/querier/tripperware/queryrange/query_range.go

@@ -243,6 +243,9 @@ func (prometheusCodec) EncodeRequest(ctx context.Context, r tripperware.Request)
 		}
 	}
 
+	// Always ask gzip to the querier
+	h.Set("Accept-Encoding", "gzip")
+
 	req := &http.Request{
 		Method:     "GET",
 		RequestURI: u.String(), // This is what the httpgrpc code looks at.