Publish Prometheus metrics about build info (kedacore#4576)

Signed-off-by: Pedro Tanaka <[email protected]>
Signed-off-by: Pedro Tanaka <[email protected]>

CHANGELOG.md

@@ -61,6 +61,7 @@ To learn more about active deprecations, we recommend checking [GitHub Discussio
 - **Pulsar Scaler**: Improve error messages for unsuccessful connections ([#4563](https://github.com/kedacore/keda/issues/4563))
 - **Security:** Enable secret scanning in GitHub repo
 - **RabbitMQ Scaler**: Add support for `unsafeSsl` in trigger metadata ([#4448](https://github.com/kedacore/keda/issues/4448))
+- **Prometheus Metrics**: Add new metric with KEDA build info ([#4647](https://github.com/kedacore/keda/issues/4647))
 
 ### Fixes
 

pkg/prommetrics/prommetrics.go

@@ -17,11 +17,14 @@ limitations under the License.
 package prommetrics
 
 import (
+	"runtime"
 	"strconv"
 
 	"github.com/prometheus/client_golang/prometheus"
 	logf "sigs.k8s.io/controller-runtime/pkg/log"
 	"sigs.k8s.io/controller-runtime/pkg/metrics"
+
+	"github.com/kedacore/keda/v2/version"
 )
 
 var log = logf.Log.WithName("prometheus_server")
@@ -36,7 +39,15 @@ const (
 )
 
 var (
-	metricLabels      = []string{"namespace", "metric", "scaledObject", "scaler", "scalerIndex"}
+	metricLabels = []string{"namespace", "metric", "scaledObject", "scaler", "scalerIndex"}
+	buildInfo    = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Namespace: DefaultPromMetricsNamespace,
+			Name:      "build_info",
+			Help:      "A metric with a constant '1' value labeled by version, git_commit and goversion from which KEDA was built.",
+		},
+		[]string{"version", "git_commit", "goversion", "goos", "goarch"},
+	)
 	scalerErrorsTotal = prometheus.NewCounterVec(
 		prometheus.CounterOpts{
 			Namespace: DefaultPromMetricsNamespace,
@@ -121,6 +132,9 @@ func init() {
 
 	metrics.Registry.MustRegister(triggerTotalsGaugeVec)
 	metrics.Registry.MustRegister(crdTotalsGaugeVec)
+	metrics.Registry.MustRegister(buildInfo)
+
+	RecordBuildInfo()
 }
 
 // RecordScalerMetric create a measurement of the external metric used by the HPA
@@ -173,6 +187,11 @@ func RecordScaledObjectError(namespace string, scaledObject string, err error) {
 	}
 }
 
+// RecordBuildInfo publishes information about KEDA version and runtime info through an info metric (gauge).
+func RecordBuildInfo() {
+	buildInfo.WithLabelValues(version.Version, version.GitCommit, runtime.Version(), runtime.GOOS, runtime.GOARCH).Set(1)
+}
+
 func getLabels(namespace string, scaledObject string, scaler string, scalerIndex int, metric string) prometheus.Labels {
 	return prometheus.Labels{"namespace": namespace, "scaledObject": scaledObject, "scaler": scaler, "scalerIndex": strconv.Itoa(scalerIndex), "metric": metric}
 }

tests/sequential/prometheus_metrics/prometheus_metrics_test.go

@@ -4,15 +4,18 @@
 package prometheus_metrics_test
 
 import (
+	"bytes"
 	"context"
 	"fmt"
+	"os/exec"
 	"strings"
 	"testing"
 	"time"
 
 	prommodel "github.com/prometheus/client_model/go"
 	"github.com/prometheus/common/expfmt"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 	v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/client-go/kubernetes"
 
@@ -581,6 +584,44 @@ func testOperatorMetricValues(t *testing.T, kc *kubernetes.Clientset) {
 
 	checkTriggerTotalValues(t, families, expectedTriggerTotals)
 	checkCRTotalValues(t, families, expectedCrTotals)
+	checkBuildInfo(t, families)
+}
+
+func checkBuildInfo(t *testing.T, families map[string]*prommodel.MetricFamily) {
+	t.Log("--- testing build info metric ---")
+
+	family, ok := families["keda_build_info"]
+	if !ok {
+		t.Errorf("metric not available")
+		return
+	}
+
+	latestCommit := getLatestCommit(t)
+	expected := map[string]string{
+		"git_commit": latestCommit,
+		"goos":       "linux",
+	}
+
+	metrics := family.GetMetric()
+	for _, metric := range metrics {
+		labels := metric.GetLabel()
+		for _, labelPair := range labels {
+			if expectedValue, ok := expected[*labelPair.Name]; ok {
+				assert.EqualValues(t, expectedValue, *labelPair.Value, "values do not match for label %s", *labelPair.Name)
+			}
+		}
+		assert.EqualValues(t, 1, metric.GetGauge().GetValue())
+	}
+}
+
+func getLatestCommit(t *testing.T) string {
+	cmd := exec.Command("git", "rev-parse", "HEAD")
+	var out bytes.Buffer
+	cmd.Stdout = &out
+	err := cmd.Run()
+	require.NoError(t, err)
+
+	return strings.Trim(out.String(), "\n")
 }
 
 func checkTriggerTotalValues(t *testing.T, families map[string]*prommodel.MetricFamily, expected map[string]int) {