upgrade web/ to use protojson (#7995)

As part of #7881 it is recommended we upgrade to use `protojson` instead of `jsonPb`. This required a few additional changes in the code since the signature of `Marshal` changed so I've split this out into a separate change.

`Marshal` now returns the resulting bytes instead of taking an interface to write those bytes into. This means we have to handle the error separately and then write the JSON into the given writer.

Signed-off-by: Kevin Leimkuhler <kleimkuhler@icloud.com>

web/srv/api_handlers.go

@@ -11,8 +11,6 @@ import (
 	"strings"
 	"time"
 
-	"github.com/golang/protobuf/jsonpb"
-	"github.com/golang/protobuf/proto"
 	"github.com/gorilla/websocket"
 	"github.com/julienschmidt/httprouter"
 	"github.com/linkerd/linkerd2/pkg/healthcheck"
@@ -23,6 +21,8 @@ import (
 	tapPb "github.com/linkerd/linkerd2/viz/tap/gen/tap"
 	tappkg "github.com/linkerd/linkerd2/viz/tap/pkg"
 	log "github.com/sirupsen/logrus"
+	"google.golang.org/protobuf/encoding/protojson"
+	"google.golang.org/protobuf/proto"
 	kerrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"sigs.k8s.io/yaml"
@@ -40,7 +40,7 @@ type (
 
 var (
 	defaultResourceType = k8s.Deployment
-	pbMarshaler         = jsonpb.Marshaler{EmitDefaults: true}
+	pbMarshaler         = protojson.MarshalOptions{EmitUnpopulated: true}
 	maxMessageSize      = 2048
 	websocketUpgrader   = websocket.Upgrader{
 		ReadBufferSize:  maxMessageSize,
@@ -76,9 +76,11 @@ func renderJSON(w http.ResponseWriter, resp interface{}) {
 
 func renderJSONPb(w http.ResponseWriter, msg proto.Message) {
 	w.Header().Set("Content-Type", "application/json")
-	// Callers of renderJSONPb pass in msgs that can be serialized into JSON.
-	//nolint:errcheck
-	pbMarshaler.Marshal(w, msg)
+	json, err := pbMarshaler.Marshal(msg)
+	if err != nil {
+		renderJSONError(w, err, http.StatusBadRequest)
+	}
+	w.Write(json)
 }
 
 func renderJSONBytes(w http.ResponseWriter, b []byte) {
@@ -170,11 +172,14 @@ func (h *handler) handleAPIStat(w http.ResponseWriter, req *http.Request, p http
 	}
 
 	// Marshal result into json and cache it
-	var resultJSON bytes.Buffer
-	if err := pbMarshaler.Marshal(&resultJSON, result); err != nil {
+	json, err := pbMarshaler.Marshal(result)
+	if err != nil {
 		renderJSONError(w, err, http.StatusInternalServerError)
 		return
 	}
+	var resultJSON bytes.Buffer
+	resultJSON.Write(json)
+
 	h.statCache.SetDefault(req.URL.RawQuery, resultJSON.Bytes())
 
 	renderJSONBytes(w, resultJSON.Bytes())
@@ -297,12 +302,13 @@ func (h *handler) handleAPITap(w http.ResponseWriter, req *http.Request, p httpr
 				break
 			}
 
-			buf := new(bytes.Buffer)
-			err = pbMarshaler.Marshal(buf, &event)
+			json, err := pbMarshaler.Marshal(&event)
 			if err != nil {
 				websocketError(ws, websocket.CloseInternalServerErr, err)
 				break
 			}
+			buf := new(bytes.Buffer)
+			buf.Write(json)
 
 			if err := ws.WriteMessage(websocket.TextMessage, buf.Bytes()); err != nil {
 				if websocket.IsUnexpectedCloseError(err, websocket.CloseNormalClosure) {

web/srv/api_handlers_test.go

@@ -155,8 +155,13 @@ func TestHandleApiGateway(t *testing.T) {
 		if err != nil {
 			t.Fatalf("not expecting error compacting api check output golden file but got: %v", err)
 		}
-		if !bytes.Equal(body, apiGatewayOutputGoldenCompact.Bytes()) {
-			t.Errorf("expecting response body to be\n %s\n but got\n %s", apiGatewayOutputGoldenCompact.Bytes(), body)
+		bodyCompact := &bytes.Buffer{}
+		err = json.Compact(bodyCompact, body)
+		if err != nil {
+			t.Fatalf("failed to compact response body: %s", err)
+		}
+		if !bytes.Equal(bodyCompact.Bytes(), apiGatewayOutputGoldenCompact.Bytes()) {
+			t.Errorf("expecting response body to be\n %s\n but got\n %s", apiGatewayOutputGoldenCompact.Bytes(), bodyCompact.Bytes())
 		}
 	})