all: consistently return text-based HTTP responses with charset=utf-8

This is a follow-up for https://github.com/VictoriaMetrics/VictoriaMetrics/pull/897

app/vmagent/main.go

@@ -228,7 +228,7 @@ func requestHandler(w http.ResponseWriter, r *http.Request) bool {
 			errMsg := fmt.Sprintf("waiting for scrapes to init, left: %d", rdy)
 			http.Error(w, errMsg, http.StatusTooEarly)
 		} else {
-			w.Header().Set("Content-Type", "text/plain")
+			w.Header().Set("Content-Type", "text/plain; charset=utf-8")
 			w.WriteHeader(http.StatusOK)
 			w.Write([]byte("OK"))
 		}

app/vmalert/datasource/vm.go

@@ -82,7 +82,7 @@ func (s *VMStorage) Query(ctx context.Context, query string) ([]Metric, error) {
 	if err != nil {
 		return nil, err
 	}
-	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Content-Type", "application/json; charset=utf-8")
 	if s.basicAuthPass != "" {
 		req.SetBasicAuth(s.basicAuthUser, s.basicAuthPass)
 	}

app/vmalert/notifier/alertmanager.go

@@ -28,7 +28,7 @@ func (am *AlertManager) Send(ctx context.Context, alerts []Alert) error {
 	if err != nil {
 		return err
 	}
-	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Content-Type", "application/json; charset=utf-8")
 	req = req.WithContext(ctx)
 	if am.basicAuthPass != "" {
 		req.SetBasicAuth(am.basicAuthUser, am.basicAuthPass)

app/vmalert/web.go

@@ -40,7 +40,7 @@ func (rh *requestHandler) handler(w http.ResponseWriter, r *http.Request) bool {
 			httpserver.Errorf(w, r, "error in %q: %s", r.URL.Path, err)
 			return true
 		}
-		w.Header().Set("Content-Type", "application/json")
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
 		w.Write(data)
 		return true
 	case "/api/v1/alerts":
@@ -49,7 +49,7 @@ func (rh *requestHandler) handler(w http.ResponseWriter, r *http.Request) bool {
 			httpserver.Errorf(w, r, "error in %q: %s", r.URL.Path, err)
 			return true
 		}
-		w.Header().Set("Content-Type", "application/json")
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
 		w.Write(data)
 		return true
 	case "/-/reload":
@@ -67,7 +67,7 @@ func (rh *requestHandler) handler(w http.ResponseWriter, r *http.Request) bool {
 			httpserver.Errorf(w, r, "error in %q: %s", r.URL.Path, err)
 			return true
 		}
-		w.Header().Set("Content-Type", "application/json")
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
 		w.Write(data)
 		return true
 	}

app/vminsert/main.go

@@ -155,13 +155,13 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 		return true
 	case "/targets":
 		promscrapeTargetsRequests.Inc()
-		w.Header().Set("Content-Type", "text/plain")
+		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
 		showOriginalLabels, _ := strconv.ParseBool(r.FormValue("show_original_labels"))
 		promscrape.WriteHumanReadableTargetsStatus(w, showOriginalLabels)
 		return true
 	case "/api/v1/targets":
 		promscrapeAPIV1TargetsRequests.Inc()
-		w.Header().Set("Content-Type", "application/json")
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
 		state := r.FormValue("state")
 		promscrape.WriteAPIV1Targets(w, state)
 		return true
@@ -175,7 +175,7 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 			errMsg := fmt.Sprintf("waiting for scrape config to init targets, configs left: %d", rdy)
 			http.Error(w, errMsg, http.StatusTooEarly)
 		} else {
-			w.Header().Set("Content-Type", "text/plain")
+			w.Header().Set("Content-Type", "text/plain; charset=utf-8")
 			w.WriteHeader(http.StatusOK)
 			w.Write([]byte("OK"))
 		}

app/vmselect/graphite/graphite.go

@@ -84,9 +84,9 @@ func MetricsFindHandler(startTime time.Time, w http.ResponseWriter, r *http.Requ
 	}
 	paths = deduplicatePaths(paths, delimiter)
 	sortPaths(paths, delimiter)
-	contentType := "application/json"
+	contentType := "application/json; charset=utf-8"
 	if jsonp != "" {
-		contentType = "text/javascript"
+		contentType = "text/javascript; charset=utf-8"
 	}
 	w.Header().Set("Content-Type", contentType)
 	bw := bufferedwriter.Get(w)
@@ -166,9 +166,9 @@ func MetricsExpandHandler(startTime time.Time, w http.ResponseWriter, r *http.Re
 		}
 		m[query] = paths
 	}
-	contentType := "application/json"
+	contentType := "application/json; charset=utf-8"
 	if jsonp != "" {
-		contentType = "text/javascript"
+		contentType = "text/javascript; charset=utf-8"
 	}
 	w.Header().Set("Content-Type", contentType)
 	if groupByExpr {
@@ -215,9 +215,9 @@ func MetricsIndexHandler(startTime time.Time, w http.ResponseWriter, r *http.Req
 	if err != nil {
 		return fmt.Errorf(`cannot obtain metric names: %w`, err)
 	}
-	contentType := "application/json"
+	contentType := "application/json; charset=utf-8"
 	if jsonp != "" {
-		contentType = "text/javascript"
+		contentType = "text/javascript; charset=utf-8"
 	}
 	w.Header().Set("Content-Type", contentType)
 	bw := bufferedwriter.Get(w)

app/vmselect/main.go

@@ -262,19 +262,19 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 	case "/api/v1/rules":
 		// Return dumb placeholder
 		rulesRequests.Inc()
-		w.Header().Set("Content-Type", "application/json")
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
 		fmt.Fprintf(w, "%s", `{"status":"success","data":{"groups":[]}}`)
 		return true
 	case "/api/v1/alerts":
 		// Return dumb placehloder
 		alertsRequests.Inc()
-		w.Header().Set("Content-Type", "application/json")
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
 		fmt.Fprintf(w, "%s", `{"status":"success","data":{"alerts":[]}}`)
 		return true
 	case "/api/v1/metadata":
 		// Return dumb placeholder
 		metadataRequests.Inc()
-		w.Header().Set("Content-Type", "application/json")
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
 		fmt.Fprintf(w, "%s", `{"status":"success","data":{}}`)
 		return true
 	case "/api/v1/admin/tsdb/delete_series":
@@ -299,7 +299,7 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 func sendPrometheusError(w http.ResponseWriter, r *http.Request, err error) {
 	logger.Warnf("error in %q: %s", r.RequestURI, err)
 
-	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
 	statusCode := http.StatusUnprocessableEntity
 	var esc *httpserver.ErrorWithStatusCode
 	if errors.As(err, &esc) {

app/vmselect/prometheus/prometheus.go

@@ -88,7 +88,7 @@ func FederateHandler(startTime time.Time, w http.ResponseWriter, r *http.Request
 		return fmt.Errorf("cannot fetch data for %q: %w", sq, err)
 	}
 
-	w.Header().Set("Content-Type", "text/plain")
+	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	err = rss.RunParallel(func(rs *netstorage.Result, workerID uint) error {
@@ -151,7 +151,7 @@ func ExportCSVHandler(startTime time.Time, w http.ResponseWriter, r *http.Reques
 		MaxTimestamp: end,
 		TagFilterss:  tagFilterss,
 	}
-	w.Header().Set("Content-Type", "text/csv")
+	w.Header().Set("Content-Type", "text/csv; charset=utf-8")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 
@@ -331,9 +331,9 @@ func exportHandler(w http.ResponseWriter, matches []string, start, end int64, fo
 		WriteExportJSONLine(bb, xb)
 		resultsCh <- bb
 	}
-	contentType := "application/stream+json"
+	contentType := "application/stream+json; charset=utf-8"
 	if format == "prometheus" {
-		contentType = "text/plain"
+		contentType = "text/plain; charset=utf-8"
 		writeLineFunc = func(xb *exportBlock, resultsCh chan<- *quicktemplate.ByteBuffer) {
 			bb := quicktemplate.AcquireByteBuffer()
 			WriteExportPrometheusLine(bb, xb)
@@ -561,7 +561,7 @@ func LabelValuesHandler(startTime time.Time, labelName string, w http.ResponseWr
 		}
 	}
 
-	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	WriteLabelValuesResponse(bw, labelValues)
@@ -639,7 +639,7 @@ func LabelsCountHandler(startTime time.Time, w http.ResponseWriter, r *http.Requ
 	if err != nil {
 		return fmt.Errorf(`cannot obtain label entries: %w`, err)
 	}
-	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	WriteLabelsCountResponse(bw, labelEntries)
@@ -690,7 +690,7 @@ func TSDBStatusHandler(startTime time.Time, w http.ResponseWriter, r *http.Reque
 	if err != nil {
 		return fmt.Errorf(`cannot obtain tsdb status for date=%d, topN=%d: %w`, date, topN, err)
 	}
-	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	WriteTSDBStatusResponse(bw, status)
@@ -760,7 +760,7 @@ func LabelsHandler(startTime time.Time, w http.ResponseWriter, r *http.Request)
 		}
 	}
 
-	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	WriteLabelsResponse(bw, labels)
@@ -826,7 +826,7 @@ func SeriesCountHandler(startTime time.Time, w http.ResponseWriter, r *http.Requ
 	if err != nil {
 		return fmt.Errorf("cannot obtain series count: %w", err)
 	}
-	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	WriteSeriesCountResponse(bw, n)
@@ -883,7 +883,7 @@ func SeriesHandler(startTime time.Time, w http.ResponseWriter, r *http.Request)
 		return fmt.Errorf("cannot fetch data for %q: %w", sq, err)
 	}
 
-	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	resultsCh := make(chan *quicktemplate.ByteBuffer)
@@ -1020,7 +1020,7 @@ func QueryHandler(startTime time.Time, w http.ResponseWriter, r *http.Request) e
 		}
 	}
 
-	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	WriteQueryResponse(bw, result)
@@ -1119,7 +1119,7 @@ func queryRangeHandler(startTime time.Time, w http.ResponseWriter, query string,
 	// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/153
 	result = removeEmptyValuesAndTimeseries(result)
 
-	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	WriteQueryRangeResponse(bw, result)

app/vmstorage/main.go

@@ -251,7 +251,7 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 
 	switch path {
 	case "/create":
-		w.Header().Set("Content-Type", "application/json")
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
 		snapshotPath, err := Storage.CreateSnapshot()
 		if err != nil {
 			err = fmt.Errorf("cannot create snapshot: %w", err)
@@ -265,7 +265,7 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 		}
 		return true
 	case "/list":
-		w.Header().Set("Content-Type", "application/json")
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
 		snapshots, err := Storage.ListSnapshots()
 		if err != nil {
 			err = fmt.Errorf("cannot list snapshots: %w", err)
@@ -282,7 +282,7 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 		fmt.Fprintf(w, `]}`)
 		return true
 	case "/delete":
-		w.Header().Set("Content-Type", "application/json")
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
 		snapshotName := r.FormValue("snapshot")
 		if err := Storage.DeleteSnapshot(snapshotName); err != nil {
 			err = fmt.Errorf("cannot delete snapshot %q: %w", snapshotName, err)
@@ -292,7 +292,7 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 		fmt.Fprintf(w, `{"status":"ok"}`)
 		return true
 	case "/delete_all":
-		w.Header().Set("Content-Type", "application/json")
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
 		snapshots, err := Storage.ListSnapshots()
 		if err != nil {
 			err = fmt.Errorf("cannot list snapshots: %w", err)

docs/CHANGELOG.md

@@ -10,6 +10,8 @@
 * FEATURE: add `-search.treatDotsAsIsInRegexps` command-line flag, which can be used for automatic escaping of dots in regexp label filters used in queries.
   For example, if `-search.treatDotsAsIsInRegexps` is set, then the query `foo{bar=~"aaa.bb.cc|dd.eee"}` is automatically converted to `foo{bar=~"aaa\\.bb\\.cc|dd\\.eee"}`.
   This may be useful for querying Graphite data.
+* FEATURE: consistently return text-based HTTP responses such as `plain/text` and `application/json` with `charset=utf-8`.
+  See https://github.com/VictoriaMetrics/VictoriaMetrics/pull/897
 
 * BUGFIX: do not return data points in the end of the selected time range for time series ending in the middle of the selected time range.
   See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/887 and https://github.com/VictoriaMetrics/VictoriaMetrics/issues/845

lib/httpserver/httpserver.go

@@ -208,7 +208,7 @@ func handlerWrapper(s *server, w http.ResponseWriter, r *http.Request, rh Reques
 	r.URL.Path = path
 	switch r.URL.Path {
 	case "/health":
-		w.Header().Set("Content-Type", "text/plain")
+		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
 		deadline := atomic.LoadInt64(&s.shutdownDelayDeadline)
 		if deadline <= 0 {
 			w.Write([]byte("OK"))
@@ -244,7 +244,7 @@ func handlerWrapper(s *server, w http.ResponseWriter, r *http.Request, rh Reques
 			return
 		}
 		startTime := time.Now()
-		w.Header().Set("Content-Type", "text/plain")
+		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
 		WritePrometheusMetrics(w)
 		metricsHandlerDuration.UpdateDuration(startTime)
 		return
@@ -395,7 +395,7 @@ func (zrw *gzipResponseWriter) Write(p []byte) (int, error) {
 			if h.Get("Content-Type") == "" {
 				// Disable auto-detection of content-type, since it
 				// is incorrectly detected after the compression.
-				h.Set("Content-Type", "text/html")
+				h.Set("Content-Type", "text/html; charset=utf-8")
 			}
 		}
 		zrw.writeHeader()