all: consistently return application/json content-type without charset=utf-8

The `application/json` content-type has utf-8 encoding by default.
See https://stackoverflow.com/questions/9254891/what-does-content-type-application-json-charset-utf-8-really-mean

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/pull/897

app/vmagent/main.go

@@ -236,26 +236,26 @@ func requestHandler(w http.ResponseWriter, r *http.Request) bool {
 			return true
 		}
 		// See https://docs.datadoghq.com/api/latest/metrics/#submit-metrics
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		w.WriteHeader(202)
 		fmt.Fprintf(w, `{"status":"ok"}`)
 		return true
 	case "/datadog/api/v1/validate":
 		datadogValidateRequests.Inc()
 		// See https://docs.datadoghq.com/api/latest/authentication/#validate-api-key
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		fmt.Fprintf(w, `{"valid":true}`)
 		return true
 	case "/datadog/api/v1/check_run":
 		datadogCheckRunRequests.Inc()
 		// See https://docs.datadoghq.com/api/latest/service-checks/#submit-a-service-check
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		w.WriteHeader(202)
 		fmt.Fprintf(w, `{"status":"ok"}`)
 		return true
 	case "/datadog/intake/":
 		datadogIntakeRequests.Inc()
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		fmt.Fprintf(w, `{}`)
 		return true
 	case "/targets":
@@ -277,7 +277,7 @@ func requestHandler(w http.ResponseWriter, r *http.Request) bool {
 		return true
 	case "/api/v1/targets":
 		promscrapeAPIV1TargetsRequests.Inc()
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		state := r.FormValue("state")
 		promscrape.WriteAPIV1Targets(w, state)
 		return true
@@ -391,19 +391,19 @@ func processMultitenantRequest(w http.ResponseWriter, r *http.Request, path stri
 	case "datadog/api/v1/validate":
 		datadogValidateRequests.Inc()
 		// See https://docs.datadoghq.com/api/latest/authentication/#validate-api-key
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		fmt.Fprintf(w, `{"valid":true}`)
 		return true
 	case "datadog/api/v1/check_run":
 		datadogCheckRunRequests.Inc()
 		// See https://docs.datadoghq.com/api/latest/service-checks/#submit-a-service-check
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		w.WriteHeader(202)
 		fmt.Fprintf(w, `{"status":"ok"}`)
 		return true
 	case "datadog/intake/":
 		datadogIntakeRequests.Inc()
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		fmt.Fprintf(w, `{}`)
 		return true
 	default:

app/vmalert/datasource/vm.go

@@ -150,7 +150,7 @@ func (s *VMStorage) newRequestPOST() (*http.Request, error) {
 	if err != nil {
 		return nil, err
 	}
-	req.Header.Set("Content-Type", "application/json; charset=utf-8")
+	req.Header.Set("Content-Type", "application/json")
 	if s.authCfg != nil {
 		if auth := s.authCfg.GetAuthHeader(); auth != "" {
 			req.Header.Set("Authorization", auth)

app/vmalert/notifier/alertmanager.go

@@ -32,7 +32,7 @@ func (am *AlertManager) Send(ctx context.Context, alerts []Alert) error {
 	if err != nil {
 		return err
 	}
-	req.Header.Set("Content-Type", "application/json; charset=utf-8")
+	req.Header.Set("Content-Type", "application/json")
 	req = req.WithContext(ctx)
 	if am.basicAuthPass != "" {
 		req.SetBasicAuth(am.basicAuthUser, am.basicAuthPass)

app/vmalert/web.go

@@ -68,7 +68,7 @@ func (rh *requestHandler) handler(w http.ResponseWriter, r *http.Request) bool {
 			httpserver.Errorf(w, r, "%s", err)
 			return true
 		}
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		w.Write(data)
 		return true
 	case "/api/v1/alerts":
@@ -77,7 +77,7 @@ func (rh *requestHandler) handler(w http.ResponseWriter, r *http.Request) bool {
 			httpserver.Errorf(w, r, "%s", err)
 			return true
 		}
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		w.Write(data)
 		return true
 	case "/-/reload":
@@ -102,7 +102,7 @@ func (rh *requestHandler) handler(w http.ResponseWriter, r *http.Request) bool {
 				httpserver.Errorf(w, r, "failed to marshal alert: %s", err)
 				return true
 			}
-			w.Header().Set("Content-Type", "application/json; charset=utf-8")
+			w.Header().Set("Content-Type", "application/json")
 			w.Write(data)
 			return true
 		}

app/vminsert/main.go

@@ -165,26 +165,26 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 			return true
 		}
 		// See https://docs.datadoghq.com/api/latest/metrics/#submit-metrics
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		w.WriteHeader(202)
 		fmt.Fprintf(w, `{"status":"ok"}`)
 		return true
 	case "/datadog/api/v1/validate":
 		datadogValidateRequests.Inc()
 		// See https://docs.datadoghq.com/api/latest/authentication/#validate-api-key
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		fmt.Fprintf(w, `{"valid":true}`)
 		return true
 	case "/datadog/api/v1/check_run":
 		datadogCheckRunRequests.Inc()
 		// See https://docs.datadoghq.com/api/latest/service-checks/#submit-a-service-check
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		w.WriteHeader(202)
 		fmt.Fprintf(w, `{"status":"ok"}`)
 		return true
 	case "/datadog/intake/":
 		datadogIntakeRequests.Inc()
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		fmt.Fprintf(w, `{}`)
 		return true
 	case "/prometheus/targets", "/targets":
@@ -193,7 +193,7 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 		return true
 	case "/prometheus/api/v1/targets", "/api/v1/targets":
 		promscrapeAPIV1TargetsRequests.Inc()
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		state := r.FormValue("state")
 		promscrape.WriteAPIV1Targets(w, state)
 		return true

app/vmselect/graphite/metrics_api.go

@@ -456,7 +456,7 @@ const maxRegexpCacheSize = 10000
 
 func getContentType(jsonp string) string {
 	if jsonp == "" {
-		return "application/json; charset=utf-8"
+		return "application/json"
 	}
 	return "text/javascript; charset=utf-8"
 }

app/vmselect/graphite/tags_api.go

@@ -62,7 +62,7 @@ func TagsDelSeriesHandler(startTime time.Time, w http.ResponseWriter, r *http.Re
 		totalDeleted += n
 	}
 
-	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.Header().Set("Content-Type", "application/json")
 	if totalDeleted > 0 {
 		fmt.Fprintf(w, "true")
 	} else {
@@ -141,7 +141,7 @@ func registerMetrics(startTime time.Time, w http.ResponseWriter, r *http.Request
 	// Return response
 	contentType := "text/plain; charset=utf-8"
 	if isJSONResponse {
-		contentType = "application/json; charset=utf-8"
+		contentType = "application/json"
 	}
 	w.Header().Set("Content-Type", contentType)
 	WriteTagsTagMultiSeriesResponse(w, canonicalPaths, isJSONResponse)
@@ -362,7 +362,7 @@ func TagsFindSeriesHandler(startTime time.Time, w http.ResponseWriter, r *http.R
 		paths = paths[:limit]
 	}
 
-	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.Header().Set("Content-Type", "application/json")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	WriteTagsFindSeriesResponse(bw, paths)
@@ -418,7 +418,7 @@ func TagValuesHandler(startTime time.Time, tagName string, w http.ResponseWriter
 		return err
 	}
 
-	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.Header().Set("Content-Type", "application/json")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	WriteTagValuesResponse(bw, tagName, tagValues)
@@ -449,7 +449,7 @@ func TagsHandler(startTime time.Time, w http.ResponseWriter, r *http.Request) er
 		return err
 	}
 
-	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.Header().Set("Content-Type", "application/json")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	WriteTagsResponse(bw, labels)

app/vmselect/main.go

@@ -200,7 +200,7 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 	}
 	if strings.HasPrefix(path, "/functions") {
 		graphiteFunctionsRequests.Inc()
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		fmt.Fprintf(w, "%s", `{}`)
 		return true
 	}
@@ -404,25 +404,25 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 	case "/api/v1/rules", "/rules":
 		// Return dumb placeholder for https://prometheus.io/docs/prometheus/latest/querying/api/#rules
 		rulesRequests.Inc()
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		fmt.Fprintf(w, "%s", `{"status":"success","data":{"groups":[]}}`)
 		return true
 	case "/api/v1/alerts", "/alerts":
 		// Return dumb placeholder for https://prometheus.io/docs/prometheus/latest/querying/api/#alerts
 		alertsRequests.Inc()
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		fmt.Fprintf(w, "%s", `{"status":"success","data":{"alerts":[]}}`)
 		return true
 	case "/api/v1/metadata":
 		// Return dumb placeholder for https://prometheus.io/docs/prometheus/latest/querying/api/#querying-metric-metadata
 		metadataRequests.Inc()
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		fmt.Fprintf(w, "%s", `{"status":"success","data":{}}`)
 		return true
 	case "/api/v1/query_exemplars":
 		// Return dumb placeholder for https://prometheus.io/docs/prometheus/latest/querying/api/#querying-exemplars
 		queryExemplarsRequests.Inc()
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		fmt.Fprintf(w, "%s", `{"status":"success","data":null}`)
 		return true
 	case "/api/v1/admin/tsdb/delete_series":
@@ -459,7 +459,7 @@ func isGraphiteTagsPath(path string) bool {
 func sendPrometheusError(w http.ResponseWriter, r *http.Request, err error) {
 	logger.Warnf("error in %q: %s", httpserver.GetRequestURI(r), err)
 
-	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.Header().Set("Content-Type", "application/json")
 	statusCode := http.StatusUnprocessableEntity
 	var esc *httpserver.ErrorWithStatusCode
 	if errors.As(err, &esc) {

app/vmselect/prometheus/prometheus.go

@@ -533,7 +533,7 @@ func LabelValuesHandler(startTime time.Time, labelName string, w http.ResponseWr
 		}
 	}
 
-	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.Header().Set("Content-Type", "application/json")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	WriteLabelValuesResponse(bw, labelValues)
@@ -622,7 +622,7 @@ 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; charset=utf-8")
+	w.Header().Set("Content-Type", "application/json")
 	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
 			return fmt.Errorf("cannot obtain tsdb status with matches for date=%d, topN=%d: %w", date, topN, err)
 		}
 	}
-	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.Header().Set("Content-Type", "application/json")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	WriteTSDBStatusResponse(bw, status)
@@ -784,7 +784,7 @@ func LabelsHandler(startTime time.Time, w http.ResponseWriter, r *http.Request)
 		}
 	}
 
-	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.Header().Set("Content-Type", "application/json")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	WriteLabelsResponse(bw, labels)
@@ -860,7 +860,7 @@ 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; charset=utf-8")
+	w.Header().Set("Content-Type", "application/json")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	WriteSeriesCountResponse(bw, n)
@@ -911,7 +911,7 @@ func SeriesHandler(startTime time.Time, w http.ResponseWriter, r *http.Request)
 		if err != nil {
 			return fmt.Errorf("cannot fetch time series for %q: %w", sq, err)
 		}
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		bw := bufferedwriter.Get(w)
 		defer bufferedwriter.Put(bw)
 		resultsCh := make(chan *quicktemplate.ByteBuffer)
@@ -936,7 +936,7 @@ 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; charset=utf-8")
+	w.Header().Set("Content-Type", "application/json")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	resultsCh := make(chan *quicktemplate.ByteBuffer)
@@ -1070,7 +1070,7 @@ func QueryHandler(startTime time.Time, w http.ResponseWriter, r *http.Request) e
 		}
 	}
 
-	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.Header().Set("Content-Type", "application/json")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	WriteQueryResponse(bw, result)
@@ -1163,7 +1163,7 @@ 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; charset=utf-8")
+	w.Header().Set("Content-Type", "application/json")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	WriteQueryRangeResponse(bw, result)
@@ -1343,7 +1343,7 @@ func QueryStatsHandler(startTime time.Time, w http.ResponseWriter, r *http.Reque
 		return fmt.Errorf("cannot parse `maxLifetime` arg: %w", err)
 	}
 	maxLifetime := time.Duration(maxLifetimeMsecs) * time.Millisecond
-	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.Header().Set("Content-Type", "application/json")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	querystats.WriteJSONQueryStats(bw, topN, maxLifetime)

app/vmstorage/main.go

@@ -304,7 +304,7 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 
 	switch path {
 	case "/create":
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		snapshotPath, err := Storage.CreateSnapshot()
 		if err != nil {
 			err = fmt.Errorf("cannot create snapshot: %w", err)
@@ -318,7 +318,7 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 		}
 		return true
 	case "/list":
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		snapshots, err := Storage.ListSnapshots()
 		if err != nil {
 			err = fmt.Errorf("cannot list snapshots: %w", err)
@@ -335,7 +335,7 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 		fmt.Fprintf(w, `]}`)
 		return true
 	case "/delete":
-		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		snapshotName := r.FormValue("snapshot")
 		if err := Storage.DeleteSnapshot(snapshotName); err != nil {
 			err = fmt.Errorf("cannot delete snapshot %q: %w", snapshotName, err)
@@ -345,7 +345,7 @@ 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; charset=utf-8")
+		w.Header().Set("Content-Type", "application/json")
 		snapshots, err := Storage.ListSnapshots()
 		if err != nil {
 			err = fmt.Errorf("cannot list snapshots: %w", err)

lib/influxutils/influxutils.go

@@ -16,7 +16,7 @@ func WriteDatabaseNames(w http.ResponseWriter) {
 	// Emulate fake response for influx query.
 	// This is required for TSBS benchmark and some Telegraf plugins.
 	// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1124
-	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.Header().Set("Content-Type", "application/json")
 	dbNames := *influxDatabaseNames
 	if len(dbNames) == 0 {
 		dbNames = []string{"_internal"}