Add REST endpoint for metrics

api/rest.go

@@ -43,6 +43,8 @@ func (api *RestApi) MountRoutes(r *mux.Router) {
 	r.HandleFunc("/jobs/{id}", api.getJob).Methods(http.MethodGet)
 	r.HandleFunc("/jobs/tag_job/{id}", api.tagJob).Methods(http.MethodPost, http.MethodPatch)
 
+	r.HandleFunc("/jobs/metrics/{id}", api.getJobMetrics).Methods(http.MethodGet)
+
 	if api.MachineStateDir != "" {
 		r.HandleFunc("/machine_state/{cluster}/{host}", api.getMachineState).Methods(http.MethodGet)
 		r.HandleFunc("/machine_state/{cluster}/{host}", api.putMachineState).Methods(http.MethodPut, http.MethodPost)
@@ -370,6 +372,52 @@ func (api *RestApi) stopJob(rw http.ResponseWriter, r *http.Request) {
 	}
 }
 
+func (api *RestApi) getJobMetrics(rw http.ResponseWriter, r *http.Request) {
+	id := mux.Vars(r)["id"]
+	metrics := r.URL.Query()["metric"]
+	var scopes []schema.MetricScope
+	for _, scope := range r.URL.Query()["scope"] {
+		var s schema.MetricScope
+		if err := s.UnmarshalGQL(scope); err != nil {
+			http.Error(rw, err.Error(), http.StatusBadRequest)
+			return
+		}
+		scopes = append(scopes, s)
+	}
+
+	rw.Header().Add("Content-Type", "application/json")
+	rw.WriteHeader(http.StatusOK)
+
+	type Respone struct {
+		Data *struct {
+			JobMetrics []*model.JobMetricWithName `json:"jobMetrics"`
+		} `json:"data"`
+		Error *struct {
+			Message string `json:"message"`
+		} `json:"error"`
+	}
+
+	data, err := api.Resolver.Query().JobMetrics(r.Context(), id, metrics, scopes)
+	if err != nil {
+		if err := json.NewEncoder(rw).Encode(Respone{
+			Error: &struct {
+				Message string "json:\"message\""
+			}{Message: err.Error()},
+		}); err != nil {
+			log.Println(err.Error())
+		}
+		return
+	}
+
+	if err := json.NewEncoder(rw).Encode(Respone{
+		Data: &struct {
+			JobMetrics []*model.JobMetricWithName "json:\"jobMetrics\""
+		}{JobMetrics: data},
+	}); err != nil {
+		log.Println(err.Error())
+	}
+}
+
 func (api *RestApi) putMachineState(rw http.ResponseWriter, r *http.Request) {
 	if api.MachineStateDir == "" {
 		http.Error(rw, "not enabled", http.StatusNotFound)

graph/schema.graphqls

@@ -103,9 +103,9 @@ type Series {
 }
 
 type MetricStatistics {
-  avg: NullableFloat!
-  min: NullableFloat!
-  max: NullableFloat!
+  avg: Float!
+  min: Float!
+  max: Float!
 }
 
 type StatsSeries {

schema/float.go

@@ -65,3 +65,41 @@ func (f Float) MarshalGQL(w io.Writer) {
 		w.Write(strconv.AppendFloat(make([]byte, 0, 10), float64(f), 'f', 2, 64))
 	}
 }
+
+// Only used via REST-API, not via GraphQL.
+// This uses a lot less allocations per series,
+// but it turns out that the performance increase
+// from using this is not that big.
+func (s *Series) MarshalJSON() ([]byte, error) {
+	buf := make([]byte, 0, 512+len(s.Data)*8)
+	buf = append(buf, `{"hostname":"`...)
+	buf = append(buf, s.Hostname...)
+	buf = append(buf, '"')
+	if s.Id != nil {
+		buf = append(buf, `,"id":`...)
+		buf = strconv.AppendInt(buf, int64(*s.Id), 10)
+	}
+	if s.Statistics != nil {
+		buf = append(buf, `,"statistics":{"min":`...)
+		buf = strconv.AppendFloat(buf, s.Statistics.Min, 'f', 2, 64)
+		buf = append(buf, `,"avg":`...)
+		buf = strconv.AppendFloat(buf, s.Statistics.Avg, 'f', 2, 64)
+		buf = append(buf, `,"max":`...)
+		buf = strconv.AppendFloat(buf, s.Statistics.Max, 'f', 2, 64)
+		buf = append(buf, '}')
+	}
+	buf = append(buf, `,"data":[`...)
+	for i := 0; i < len(s.Data); i++ {
+		if i != 0 {
+			buf = append(buf, ',')
+		}
+
+		if s.Data[i].IsNaN() {
+			buf = append(buf, `null`...)
+		} else {
+			buf = strconv.AppendFloat(buf, float64(s.Data[i]), 'f', 2, 32)
+		}
+	}
+	buf = append(buf, ']', '}')
+	return buf, nil
+}