Merge pull request #641 from prometheus/stddev

Add stddev and stdvar aggregation functions.

rules/ast/ast.go

@@ -66,9 +66,10 @@ type Vector []*Sample
 type Matrix []SampleStream
 
 type groupedAggregation struct {
-	labels     clientmodel.COWMetric
-	value      clientmodel.SampleValue
-	groupCount int
+	labels           clientmodel.COWMetric
+	value            clientmodel.SampleValue
+	valuesSquaredSum clientmodel.SampleValue
+	groupCount       int
 }
 
 // ----------------------------------------------------------------------------
@@ -128,6 +129,8 @@ const (
 	Min
 	Max
 	Count
+	Stdvar
+	Stddev
 )
 
 // ----------------------------------------------------------------------------
@@ -468,6 +471,12 @@ func (node *VectorAggregation) groupedAggregationsToVector(aggregations map[uint
 			aggregation.value = aggregation.value / clientmodel.SampleValue(aggregation.groupCount)
 		case Count:
 			aggregation.value = clientmodel.SampleValue(aggregation.groupCount)
+		case Stdvar:
+			avg := float64(aggregation.value) / float64(aggregation.groupCount)
+			aggregation.value = clientmodel.SampleValue(float64(aggregation.valuesSquaredSum)/float64(aggregation.groupCount) - avg*avg)
+		case Stddev:
+			avg := float64(aggregation.value) / float64(aggregation.groupCount)
+			aggregation.value = clientmodel.SampleValue(math.Sqrt(float64(aggregation.valuesSquaredSum)/float64(aggregation.groupCount) - avg*avg))
 		default:
 			// For other aggregations, we already have the right value.
 		}
@@ -509,6 +518,10 @@ func (node *VectorAggregation) Eval(timestamp clientmodel.Timestamp) Vector {
 				}
 			case Count:
 				groupedResult.groupCount++
+			case Stdvar, Stddev:
+				groupedResult.value += sample.Value
+				groupedResult.valuesSquaredSum += sample.Value * sample.Value
+				groupedResult.groupCount++
 			default:
 				panic("Unknown aggregation type")
 			}
@@ -529,9 +542,10 @@ func (node *VectorAggregation) Eval(timestamp clientmodel.Timestamp) Vector {
 				}
 			}
 			result[groupingKey] = &groupedAggregation{
-				labels:     m,
-				value:      sample.Value,
-				groupCount: 1,
+				labels:           m,
+				value:            sample.Value,
+				valuesSquaredSum: sample.Value * sample.Value,
+				groupCount:       1,
 			}
 		}
 	}

rules/ast/printer.go

@@ -60,11 +60,13 @@ func (opType BinOpType) String() string {
 
 func (aggrType AggrType) String() string {
 	aggrTypeMap := map[AggrType]string{
-		Sum:   "SUM",
-		Avg:   "AVG",
-		Min:   "MIN",
-		Max:   "MAX",
-		Count: "COUNT",
+		Sum:    "SUM",
+		Avg:    "AVG",
+		Min:    "MIN",
+		Max:    "MAX",
+		Count:  "COUNT",
+		Stdvar: "STDVAR",
+		Stddev: "STDDEV",
 	}
 	return aggrTypeMap[aggrType]
 }

rules/helpers.go

@@ -78,11 +78,13 @@ func NewVectorAggregation(aggrTypeStr string, vector ast.Node, groupBy clientmod
 		return nil, fmt.Errorf("operand of %v aggregation must be of vector type", aggrTypeStr)
 	}
 	var aggrTypes = map[string]ast.AggrType{
-		"SUM":   ast.Sum,
-		"MAX":   ast.Max,
-		"MIN":   ast.Min,
-		"AVG":   ast.Avg,
-		"COUNT": ast.Count,
+		"SUM":    ast.Sum,
+		"MAX":    ast.Max,
+		"MIN":    ast.Min,
+		"AVG":    ast.Avg,
+		"COUNT":  ast.Count,
+		"STDVAR": ast.Stdvar,
+		"STDDEV": ast.Stddev,
 	}
 	aggrType, ok := aggrTypes[aggrTypeStr]
 	if !ok {

rules/lexer.l

@@ -89,8 +89,8 @@ GROUP_LEFT|GROUP_RIGHT   lval.str = lexer.token(); return MATCH_MOD
 group_left|group_right   lval.str = strings.ToUpper(lexer.token()); return MATCH_MOD
 KEEPING_EXTRA|keeping_extra return KEEPING_EXTRA
 OFFSET|offset            return OFFSET
-AVG|SUM|MAX|MIN|COUNT    lval.str = lexer.token(); return AGGR_OP
-avg|sum|max|min|count    lval.str = strings.ToUpper(lexer.token()); return AGGR_OP
+AVG|SUM|MAX|MIN|COUNT|STDVAR|STDDEV    lval.str = lexer.token(); return AGGR_OP
+avg|sum|max|min|count|stdvar|stddev    lval.str = strings.ToUpper(lexer.token()); return AGGR_OP
 \<|>|AND|OR|and|or       lval.str = strings.ToUpper(lexer.token()); return CMP_OP
 ==|!=|>=|<=|=~|!~        lval.str = lexer.token(); return CMP_OP
 [+\-]                    lval.str = lexer.token(); return ADDITIVE_OP

rules/manager/manager.go

@@ -99,7 +99,7 @@ type ruleManager struct {
 	notificationHandler *notification.NotificationHandler
 
 	prometheusURL string
-	pathPrefix string
+	pathPrefix    string
 }
 
 // RuleManagerOptions bundles options for the RuleManager.
@@ -111,7 +111,7 @@ type RuleManagerOptions struct {
 	SampleAppender      storage.SampleAppender
 
 	PrometheusURL string
-	PathPrefix string
+	PathPrefix    string
 }
 
 // NewRuleManager returns an implementation of RuleManager, ready to be started

rules/rules_test.go

@@ -1197,13 +1197,13 @@ func TestExpressions(t *testing.T) {
 				`{group="canary", instance="0", job="api-server"} => NaN @[%v]`,
 			},
 		},
-    {
+		{
 			expr: `sqrt(vector_matching_a)`,
 			output: []string{
 				`{l="x"} => 3.1622776601683795 @[%v]`,
 				`{l="y"} => 4.47213595499958 @[%v]`,
 			},
-    },
+		},
 		{
 			expr: `exp(vector_matching_a)`,
 			output: []string{
@@ -1295,6 +1295,32 @@ func TestExpressions(t *testing.T) {
 				`{l="y"} => -Inf @[%v]`,
 			},
 		},
+		{
+			expr: `stddev(http_requests)`,
+			output: []string{
+				`{} => 229.12878474779 @[%v]`,
+			},
+		},
+		{
+			expr: `stddev by (instance)(http_requests)`,
+			output: []string{
+				`{instance="0"} => 223.60679774998 @[%v]`,
+				`{instance="1"} => 223.60679774998 @[%v]`,
+			},
+		},
+		{
+			expr: `stdvar(http_requests)`,
+			output: []string{
+				`{} => 52500 @[%v]`,
+			},
+		},
+		{
+			expr: `stdvar by (instance)(http_requests)`,
+			output: []string{
+				`{instance="0"} => 50000 @[%v]`,
+				`{instance="1"} => 50000 @[%v]`,
+			},
+		},
 	}
 
 	storage, closer := newTestStorage(t)

templates/templates.go

@@ -219,7 +219,7 @@ func NewTemplateExpander(text string, name string, data interface{}, timestamp c
 				return fmt.Sprintf("%.4g%ss", v, prefix)
 			},
 			"pathPrefix": func() string {
-				return pathPrefix;
+				return pathPrefix
 			},
 		},
 	}

web/api/api.go

@@ -37,13 +37,13 @@ func (msrv *MetricsService) RegisterHandler(pathPrefix string) {
 			Handler: http.HandlerFunc(h),
 		}
 	}
-	http.Handle(pathPrefix + "api/query", prometheus.InstrumentHandler(
-		pathPrefix + "api/query", handler(msrv.Query),
+	http.Handle(pathPrefix+"api/query", prometheus.InstrumentHandler(
+		pathPrefix+"api/query", handler(msrv.Query),
 	))
-	http.Handle(pathPrefix + "api/query_range", prometheus.InstrumentHandler(
-		pathPrefix + "api/query_range", handler(msrv.QueryRange),
+	http.Handle(pathPrefix+"api/query_range", prometheus.InstrumentHandler(
+		pathPrefix+"api/query_range", handler(msrv.QueryRange),
 	))
-	http.Handle(pathPrefix + "api/metrics", prometheus.InstrumentHandler(
-		pathPrefix + "api/metrics", handler(msrv.Metrics),
+	http.Handle(pathPrefix+"api/metrics", prometheus.InstrumentHandler(
+		pathPrefix+"api/metrics", handler(msrv.Metrics),
 	))
 }

web/consoles.go

@@ -33,7 +33,7 @@ var (
 
 // ConsolesHandler implements http.Handler.
 type ConsolesHandler struct {
-	Storage local.Storage
+	Storage    local.Storage
 	PathPrefix string
 }
 

web/status.go

@@ -32,7 +32,7 @@ type PrometheusStatusHandler struct {
 	RuleManager manager.RuleManager
 	TargetPools map[string]*retrieval.TargetPool
 
-	Birth time.Time
+	Birth      time.Time
 	PathPrefix string
 }
 

web/web.go

@@ -63,39 +63,39 @@ func (ws WebService) ServeForever(pathPrefix string) error {
 	http.Handle(pathPrefix, prometheus.InstrumentHandler(
 		pathPrefix, ws.StatusHandler,
 	))
-	http.Handle(pathPrefix + "alerts", prometheus.InstrumentHandler(
-		pathPrefix + "alerts", ws.AlertsHandler,
+	http.Handle(pathPrefix+"alerts", prometheus.InstrumentHandler(
+		pathPrefix+"alerts", ws.AlertsHandler,
 	))
-	http.Handle(pathPrefix + "consoles/", prometheus.InstrumentHandler(
-		pathPrefix + "consoles/", http.StripPrefix(pathPrefix + "consoles/", ws.ConsolesHandler),
+	http.Handle(pathPrefix+"consoles/", prometheus.InstrumentHandler(
+		pathPrefix+"consoles/", http.StripPrefix(pathPrefix+"consoles/", ws.ConsolesHandler),
 	))
-	http.Handle(pathPrefix + "graph", prometheus.InstrumentHandler(
-		pathPrefix + "graph", ws.GraphsHandler,
+	http.Handle(pathPrefix+"graph", prometheus.InstrumentHandler(
+		pathPrefix+"graph", ws.GraphsHandler,
 	))
-	http.Handle(pathPrefix + "heap", prometheus.InstrumentHandler(
-		pathPrefix + "heap", http.HandlerFunc(dumpHeap),
+	http.Handle(pathPrefix+"heap", prometheus.InstrumentHandler(
+		pathPrefix+"heap", http.HandlerFunc(dumpHeap),
 	))
 
 	ws.MetricsHandler.RegisterHandler(pathPrefix)
-	http.Handle(pathPrefix + strings.TrimLeft(*metricsPath, "/"), prometheus.Handler())
+	http.Handle(pathPrefix+strings.TrimLeft(*metricsPath, "/"), prometheus.Handler())
 	if *useLocalAssets {
-		http.Handle(pathPrefix + "static/", prometheus.InstrumentHandler(
-			pathPrefix + "static/", http.StripPrefix(pathPrefix + "static/", http.FileServer(http.Dir("web/static"))),
+		http.Handle(pathPrefix+"static/", prometheus.InstrumentHandler(
+			pathPrefix+"static/", http.StripPrefix(pathPrefix+"static/", http.FileServer(http.Dir("web/static"))),
 		))
 	} else {
-		http.Handle(pathPrefix + "static/", prometheus.InstrumentHandler(
-			pathPrefix + "static/", http.StripPrefix(pathPrefix + "static/", new(blob.Handler)),
+		http.Handle(pathPrefix+"static/", prometheus.InstrumentHandler(
+			pathPrefix+"static/", http.StripPrefix(pathPrefix+"static/", new(blob.Handler)),
 		))
 	}
 
 	if *userAssetsPath != "" {
-		http.Handle(pathPrefix + "user/", prometheus.InstrumentHandler(
-			pathPrefix + "user/", http.StripPrefix(pathPrefix + "user/", http.FileServer(http.Dir(*userAssetsPath))),
+		http.Handle(pathPrefix+"user/", prometheus.InstrumentHandler(
+			pathPrefix+"user/", http.StripPrefix(pathPrefix+"user/", http.FileServer(http.Dir(*userAssetsPath))),
 		))
 	}
 
 	if *enableQuit {
-		http.Handle(pathPrefix + "-/quit", http.HandlerFunc(ws.quitHandler))
+		http.Handle(pathPrefix+"-/quit", http.HandlerFunc(ws.quitHandler))
 	}
 
 	if pathPrefix != "/" {