fix: Matrics API Scaler now can read any prometheus metric (kedacore#…

…6078)

Signed-off-by: Jorge Turrado <[email protected]>

CHANGELOG.md

@@ -78,7 +78,7 @@ Here is an overview of all new **experimental** features:
 
 ### Fixes
 
-- TODO ([#XXX](https://github.com/kedacore/keda/issues/XXX))
+- **Metrics API**: Prometheus metrics can have multiple labels ([#6077](https://github.com/kedacore/keda/issues/6077))
 
 ### Deprecations
 

go.mod

@@ -210,6 +210,7 @@ require (
 	github.com/coreos/go-semver v0.3.1 // indirect
 	github.com/coreos/go-systemd/v22 v22.5.0 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
+	github.com/dennwc/varint v1.0.0 // indirect
 	github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f // indirect
 	github.com/dimchansky/utfbom v1.1.1 // indirect
 	github.com/eapache/go-resiliency v1.6.0 // indirect
@@ -224,6 +225,8 @@ require (
 	github.com/gabriel-vasile/mimetype v1.4.3 // indirect
 	github.com/go-errors/errors v1.5.1 // indirect
 	github.com/go-jose/go-jose/v4 v4.0.1 // indirect
+	github.com/go-kit/log v0.2.1 // indirect
+	github.com/go-logfmt/logfmt v0.6.0 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/go-logr/zapr v1.3.0 // indirect
 	github.com/go-openapi/jsonpointer v0.21.0 // indirect
@@ -254,6 +257,7 @@ require (
 	github.com/googleapis/enterprise-certificate-proxy v0.3.2 // indirect
 	github.com/googleapis/gax-go/v2 v2.13.0 // indirect
 	github.com/gorilla/websocket v1.5.1 // indirect
+	github.com/grafana/regexp v0.0.0-20221122212121-6b5c0a4cb7fd // indirect
 	github.com/grpc-ecosystem/go-grpc-middleware v1.4.0 // indirect
 	github.com/grpc-ecosystem/go-grpc-middleware/v2 v2.1.0 // indirect
 	github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0 // indirect
@@ -308,6 +312,7 @@ require (
 	github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/prometheus/procfs v0.15.1 // indirect
+	github.com/prometheus/prometheus v0.49.0
 	github.com/rivo/uniseg v0.4.4 // indirect
 	github.com/ryanuber/go-glob v1.0.0 // indirect
 	github.com/samber/lo v1.39.0 // indirect

go.sum

@@ -866,6 +866,8 @@ github.com/ajstarks/svgo v0.0.0-20180226025133-644b8db467af/go.mod h1:K08gAheRH3
 github.com/ajstarks/svgo v0.0.0-20211024235047-1546f124cd8b/go.mod h1:1KcenG0jGWcpt8ov532z81sp/kMMUG485J2InIOyADM=
 github.com/alecthomas/kingpin/v2 v2.3.2/go.mod h1:0gyi0zQnjuFk8xrkNKamJoyUo382HRL7ATRpFZCw6tE=
 github.com/alecthomas/units v0.0.0-20211218093645-b94a6e3cc137/go.mod h1:OMCwj8VM1Kc9e19TLln2VL61YJF0x1XFtfdL4JdbSyE=
+github.com/alecthomas/units v0.0.0-20231202071711-9a357b53e9c9 h1:ez/4by2iGztzR4L0zgAOR8lTQK9VlyBVVd7G4omaOQs=
+github.com/alecthomas/units v0.0.0-20231202071711-9a357b53e9c9/go.mod h1:OMCwj8VM1Kc9e19TLln2VL61YJF0x1XFtfdL4JdbSyE=
 github.com/andybalholm/brotli v1.0.4/go.mod h1:fO7iG3H7G2nSZ7m0zPUDn85XEX2GTukHGRSepvi9Eig=
 github.com/andybalholm/brotli v1.1.0 h1:eLKJA0d02Lf0mVpIDgYnqXcUn0GqVmEFny3VuID1U3M=
 github.com/andybalholm/brotli v1.1.0/go.mod h1:sms7XGricyQI9K10gOSf56VKKWS4oLer58Q+mhRPtnY=
@@ -891,6 +893,8 @@ github.com/asaskevich/govalidator v0.0.0-20230301143203-a9d515a09cc2 h1:DklsrG3d
 github.com/asaskevich/govalidator v0.0.0-20230301143203-a9d515a09cc2/go.mod h1:WaHUgvxTVq04UNunO+XhnAqY/wQc+bxr74GqbsZ/Jqw=
 github.com/aws/aws-msk-iam-sasl-signer-go v1.0.0 h1:UyjtGmO0Uwl/K+zpzPwLoXzMhcN9xmnR2nrqJoBrg3c=
 github.com/aws/aws-msk-iam-sasl-signer-go v1.0.0/go.mod h1:TJAXuFs2HcMib3sN5L0gUC+Q01Qvy3DemvA55WuC+iA=
+github.com/aws/aws-sdk-go v1.48.14 h1:nVLrp+F84SG+xGiFMfe1TE6ZV6smF+42tuuNgYGV30s=
+github.com/aws/aws-sdk-go v1.48.14/go.mod h1:LF8svs817+Nz+DmiMQKTO3ubZ/6IaTpq3TjupRn3Eqk=
 github.com/aws/aws-sdk-go-v2 v1.16.12/go.mod h1:C+Ym0ag2LIghJbXhfXZ0YEEp49rBWowxKzJLUoob0ts=
 github.com/aws/aws-sdk-go-v2 v1.30.3 h1:jUeBtG0Ih+ZIFH0F4UkmL9w3cSpaMv9tYYDbzILP8dY=
 github.com/aws/aws-sdk-go-v2 v1.30.3/go.mod h1:nIQjQVp5sfpQcTc9mPSr1B0PaWK5ByX9MOoDadSN4lc=
@@ -1015,6 +1019,8 @@ github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/denisenkom/go-mssqldb v0.12.3 h1:pBSGx9Tq67pBOTLmxNuirNTeB8Vjmf886Kx+8Y+8shw=
 github.com/denisenkom/go-mssqldb v0.12.3/go.mod h1:k0mtMFOnU+AihqFxPMiF05rtiDrorD1Vrm1KEz5hxDo=
+github.com/dennwc/varint v1.0.0 h1:kGNFFSSw8ToIy3obO/kKr8U9GZYUAxQEVuix4zfDWzE=
+github.com/dennwc/varint v1.0.0/go.mod h1:hnItb35rvZvJrbTALZtY/iQfDs48JKRG1RPpgziApxA=
 github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f h1:lO4WD4F/rVNCu3HqELle0jiPLLBs70cWOduZpkS1E78=
 github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f/go.mod h1:cuUVRXasLTGF7a8hSLbxyZXjz+1KgoB3wDUb6vlszIc=
 github.com/dimchansky/utfbom v1.1.1 h1:vV6w1AhK4VMnhBno/TPVCoK9U/LP0PkLCS9tbxHdi/U=
@@ -1088,6 +1094,7 @@ github.com/go-gl/glfw/v3.3/glfw v0.0.0-20200222043503-6f7a984d4dc4/go.mod h1:tQ2
 github.com/go-jose/go-jose/v4 v4.0.1 h1:QVEPDE3OluqXBQZDcnNvQrInro2h0e4eqNbnZSWqS6U=
 github.com/go-jose/go-jose/v4 v4.0.1/go.mod h1:WVf9LFMHh/QVrmqrOfqun0C45tMe3RoiKJMPvgWwLfY=
 github.com/go-kit/log v0.1.0/go.mod h1:zbhenjAZHb184qTLMA9ZjW7ThYL0H2mk7Q6pNt4vbaY=
+github.com/go-kit/log v0.2.1 h1:MRVx0/zhvdseW+Gza6N9rVzU/IVzaeE1SFI4raAhmBU=
 github.com/go-kit/log v0.2.1/go.mod h1:NwTd00d/i8cPZ3xOwwiv2PO5MOcx78fFErGNcVmBjv0=
 github.com/go-kivik/couchdb/v3 v3.4.1 h1:TlGYEFOmG5a0pN6MpDkIDdd+sn75+w5aSDTcEou02kk=
 github.com/go-kivik/couchdb/v3 v3.4.1/go.mod h1:scodbTTSS6vOAacJXaCx6XZ57qw8YH1JOvhMwvP0vuw=
@@ -1099,6 +1106,8 @@ github.com/go-latex/latex v0.0.0-20210118124228-b3d85cf34e07/go.mod h1:CO1AlKB2C
 github.com/go-latex/latex v0.0.0-20210823091927-c0d11ff05a81/go.mod h1:SX0U8uGpxhq9o2S/CELCSUxEWWAuoCUcVCQWv7G2OCk=
 github.com/go-logfmt/logfmt v0.5.0/go.mod h1:wCYkCAKZfumFQihp8CzCvQ3paCTfi41vtzG1KdI/P7A=
 github.com/go-logfmt/logfmt v0.5.1/go.mod h1:WYhtIu8zTZfxdn5+rREduYbwxfcBr/Vr6KEVveWlfTs=
+github.com/go-logfmt/logfmt v0.6.0 h1:wGYYu3uicYdqXVgoYbvnkrPVXkuLM1p1ifugDMEdRi4=
+github.com/go-logfmt/logfmt v0.6.0/go.mod h1:WYhtIu8zTZfxdn5+rREduYbwxfcBr/Vr6KEVveWlfTs=
 github.com/go-logr/logr v0.2.0/go.mod h1:z6/tIYblkpsD+a4lm/fGIIU9mZ+XfAiaFtq7xTgseGU=
 github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
 github.com/go-logr/logr v1.4.2 h1:6pFjapn8bFcIbiKo3XT4j/BhANplGihG6tvd+8rYgrY=
@@ -1309,6 +1318,8 @@ github.com/gorilla/sessions v1.2.1/go.mod h1:dk2InVEVJ0sfLlnXv9EAgkf6ecYs/i80K/z
 github.com/gorilla/websocket v1.4.2/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 github.com/gorilla/websocket v1.5.1 h1:gmztn0JnHVt9JZquRuzLw3g4wouNVzKL15iLr/zn/QY=
 github.com/gorilla/websocket v1.5.1/go.mod h1:x3kM2JMyaluk02fnUJpQuwD2dCS5NDG2ZHL0uE0tcaY=
+github.com/grafana/regexp v0.0.0-20221122212121-6b5c0a4cb7fd h1:PpuIBO5P3e9hpqBD0O/HjhShYuM6XE0i/lbE6J94kww=
+github.com/grafana/regexp v0.0.0-20221122212121-6b5c0a4cb7fd/go.mod h1:M5qHK+eWfAv8VR/265dIuEpL3fNfeC21tXXp9itM24A=
 github.com/grpc-ecosystem/go-grpc-middleware v1.0.0/go.mod h1:FiyG127CGDf3tlThmgyCl78X/SZQqEOJBCDaAfeWzPs=
 github.com/grpc-ecosystem/go-grpc-middleware v1.4.0 h1:UH//fgunKIs4JdUbpDl1VZCDaL56wXCB/5+wF6uHfaI=
 github.com/grpc-ecosystem/go-grpc-middleware v1.4.0/go.mod h1:g5qyo/la0ALbONm6Vbp88Yd8NsDy6rZz+RcrMPxvld8=
@@ -1539,6 +1550,8 @@ github.com/nxadm/tail v1.4.8 h1:nPr65rt6Y5JFSKQO7qToXr7pePgD6Gwiw05lkbyAQTE=
 github.com/nxadm/tail v1.4.8/go.mod h1:+ncqLTQzXmGhMZNUePPaPqPvBxHAIsmXswZKocGu+AU=
 github.com/oapi-codegen/runtime v1.1.1 h1:EXLHh0DXIJnWhdRPN2w4MXAzFyE4CskzhNLUmtpMYro=
 github.com/oapi-codegen/runtime v1.1.1/go.mod h1:SK9X900oXmPWilYR5/WKPzt3Kqxn/uS/+lbpREv+eCg=
+github.com/oklog/ulid v1.3.1 h1:EGfNDEx6MqHz8B3uNV6QAib1UR2Lm97sHi3ocA6ESJ4=
+github.com/oklog/ulid v1.3.1/go.mod h1:CirwcVhetQ6Lv90oh/F+FBtV6XMibvdAFo93nm5qn4U=
 github.com/olekukonko/tablewriter v0.0.5 h1:P2Ga83D34wi1o9J6Wh1mRuqd4mF/x/lgBS7N7AbDhec=
 github.com/olekukonko/tablewriter v0.0.5/go.mod h1:hPp6KlRPjbx+hW8ykQs1w3UBbZlj6HuIJcUGPhkA7kY=
 github.com/onsi/ginkgo v1.6.0/go.mod h1:lLunBs/Ym6LB5Z9jYTR76FiuTmxDTDusOGeTQH+WWjE=
@@ -1590,10 +1603,14 @@ github.com/prometheus/client_model v0.5.0 h1:VQw1hfvPvk3Uv6Qf29VrPF32JB6rtbgI6cY
 github.com/prometheus/client_model v0.5.0/go.mod h1:dTiFglRmd66nLR9Pv9f0mZi7B7fk5Pm3gvsjB5tr+kI=
 github.com/prometheus/common v0.45.0 h1:2BGz0eBc2hdMDLnO/8n0jeB3oPrt2D08CekT0lneoxM=
 github.com/prometheus/common v0.45.0/go.mod h1:YJmSTw9BoKxJplESWWxlbyttQR4uaEcGyv9MZjVOJsY=
+github.com/prometheus/common/sigv4 v0.1.0 h1:qoVebwtwwEhS85Czm2dSROY5fTo2PAPEVdDeppTwGX4=
+github.com/prometheus/common/sigv4 v0.1.0/go.mod h1:2Jkxxk9yYvCkE5G1sQT7GuEXm57JrvHu9k5YwTjsNtI=
 github.com/prometheus/procfs v0.11.1/go.mod h1:eesXgaPo1q7lBpVMoMy0ZOFTth9hBn4W/y0/p/ScXhY=
 github.com/prometheus/procfs v0.12.0/go.mod h1:pcuDEFsWDnvcgNzo4EEweacyhjeA9Zk3cnaOZAZEfOo=
 github.com/prometheus/procfs v0.15.1 h1:YagwOFzUgYfKKHX6Dr+sHT7km/hxC76UB0learggepc=
 github.com/prometheus/procfs v0.15.1/go.mod h1:fB45yRUv8NstnjriLhBQLuOUt+WW4BsoGhij/e3PBqk=
+github.com/prometheus/prometheus v0.49.0 h1:i0CEhreJo3ZcZNeK7ulISinCac0MgL0krVOGgNmfFRY=
+github.com/prometheus/prometheus v0.49.0/go.mod h1:aDogiyqmv3aBIWDb5z5Sdcxuuf2BOfiJwOIm9JGpMnI=
 github.com/rabbitmq/amqp091-go v1.10.0 h1:STpn5XsHlHGcecLmMFCtg7mqq0RnD+zFr4uzukfVhBw=
 github.com/rabbitmq/amqp091-go v1.10.0/go.mod h1:Hy4jKW5kQART1u+JkDTF9YYOQUHXqMuhrgxOEeS7G4o=
 github.com/rcrowley/go-metrics v0.0.0-20201227073835-cf1acfcdf475 h1:N/ElC8H3+5XpJzTSTfLsJV/mx9Q9g7kxmchpfZyxgzM=

pkg/scalers/metrics_api_scaler.go

@@ -1,8 +1,6 @@
 package scalers
 
 import (
-	"bufio"
-	"bytes"
 	"context"
 	"encoding/xml"
 	"errors"
@@ -14,6 +12,8 @@ import (
 	"strings"
 
 	"github.com/go-logr/logr"
+	"github.com/prometheus/common/expfmt"
+	"github.com/prometheus/prometheus/promql/parser"
 	"github.com/tidwall/gjson"
 	"gopkg.in/yaml.v3"
 	v2 "k8s.io/api/autoscaling/v2"
@@ -264,25 +264,67 @@ func GetValueFromResponse(body []byte, valueLocation string, format APIFormat) (
 
 // getValueFromPrometheusResponse uses provided valueLocation to access the numeric value in provided body
 func getValueFromPrometheusResponse(body []byte, valueLocation string) (float64, error) {
-	scanner := bufio.NewScanner(bytes.NewReader(body))
-	for scanner.Scan() {
-		line := scanner.Text()
-		fields := strings.Fields(line)
-		if len(fields) == 0 || strings.HasPrefix(fields[0], "#") {
-			continue
-		}
-		if len(fields) == 2 && strings.HasPrefix(fields[0], valueLocation) {
-			value, err := strconv.ParseFloat(fields[1], 64)
-			if err != nil {
-				return 0, err
-			}
-			return value, nil
+	matchers, err := parser.ParseMetricSelector(valueLocation)
+	if err != nil {
+		return 0, err
+	}
+	metricName := ""
+	for _, v := range matchers {
+		if v.Name == "__name__" {
+			metricName = v.Value
 		}
 	}
-
-	if err := scanner.Err(); err != nil {
+	// Ensure EOL
+	reader := strings.NewReader(strings.ReplaceAll(string(body), "\r\n", "\n"))
+	familiesParser := expfmt.TextParser{}
+	families, err := familiesParser.TextToMetricFamilies(reader)
+	if err != nil {
 		return 0, err
 	}
+	family, ok := families[metricName]
+	if !ok {
+		return 0, fmt.Errorf("metric '%s' not found", metricName)
+	}
+
+	metrics := family.GetMetric()
+	for _, metric := range metrics {
+		labels := metric.GetLabel()
+		match := true
+		for _, matcher := range matchers {
+			matcherFound := false
+			if matcher == nil {
+				continue
+			}
+			// The name has been already validated,
+			// so we can skip it and check the other labels
+			if matcher.Name == "__name__" {
+				continue
+			}
+			for _, label := range labels {
+				if *label.Name == matcher.Name &&
+					*label.Value == matcher.Value {
+					matcherFound = true
+				}
+			}
+			if !matcherFound {
+				match = false
+			}
+		}
+		if match {
+			untyped := metric.GetUntyped()
+			if untyped != nil && untyped.Value != nil {
+				return *untyped.Value, nil
+			}
+			counter := metric.GetCounter()
+			if counter != nil && counter.Value != nil {
+				return *counter.Value, nil
+			}
+			gauge := metric.GetGauge()
+			if gauge != nil && gauge.Value != nil {
+				return *gauge.Value, nil
+			}
+		}
+	}
 
 	return 0, fmt.Errorf("value %s not found", valueLocation)
 }

pkg/scalers/metrics_api_scaler_test.go

@@ -125,6 +125,16 @@ func TestMetricsAPIGetMetricSpecForScaling(t *testing.T) {
 func TestGetValueFromResponse(t *testing.T) {
 	inputJSON := []byte(`{"components":[{"id": "82328e93e", "tasks": 32, "str": "64", "k":"1k","wrong":"NaN"}],"count":2.43}`)
 	inputYAML := []byte(`{components: [{id: 82328e93e, tasks: 32, str: '64', k: 1k, wrong: NaN}], count: 2.43}`)
+	inputPrometheus := []byte(`# HELP backend_queue_size Total number of items
+	# TYPE backend_queue_size counter
+	backend_queue_size{queueName="zero"} 0
+	backend_queue_size{queueName="one"} 1
+	backend_queue_size{queueName="two", instance="random"} 2
+	backend_queue_size{queueName="two", instance="zero"} 20
+	# HELP random_metric Random metric generate to include noise
+	# TYPE random_metric counter
+	random_metric 10
+	`)
 
 	testCases := []struct {
 		name      string
@@ -143,6 +153,12 @@ func TestGetValueFromResponse(t *testing.T) {
 		{name: "string", input: inputYAML, key: "components.0.str", format: YAMLFormat, expectVal: 64},
 		{name: "{}.[].{}", input: inputYAML, key: "components.0.tasks", format: YAMLFormat, expectVal: 32},
 		{name: "invalid data", input: inputYAML, key: "components.0.wrong", format: YAMLFormat, expectErr: true},
+
+		{name: "no labels", input: inputPrometheus, key: "random_metric", format: PrometheusFormat, expectVal: 10},
+		{name: "one label", input: inputPrometheus, key: "backend_queue_size{queueName=\"one\"}", format: PrometheusFormat, expectVal: 1},
+		{name: "multiple labels not queried", input: inputPrometheus, key: "backend_queue_size{queueName=\"two\"}", format: PrometheusFormat, expectVal: 2},
+		{name: "multiple labels queried", input: inputPrometheus, key: "backend_queue_size{queueName=\"two\", instance=\"zero\"}", format: PrometheusFormat, expectVal: 20},
+		{name: "invalid data", input: inputPrometheus, key: "backend_queue_size{invalid=test}", format: PrometheusFormat, expectErr: true},
 	}
 
 	for _, tc := range testCases {