feat(metrics): publish build_info metric (#5643)

* feat(metrics): publish build_info metric

Signed-off-by: ivan katliarchuk <ivan.katliarchuk@gmail.com>

* feat(metrics): publish build_info metric

Signed-off-by: ivan katliarchuk <ivan.katliarchuk@gmail.com>

* feat(metrics): publish build_info metric

Co-authored-by: Michel Loiseleur <97035654+mloiseleur@users.noreply.github.com>

* feat(metrics): publish build_info metric

Signed-off-by: ivan katliarchuk <ivan.katliarchuk@gmail.com>

---------

Signed-off-by: ivan katliarchuk <ivan.katliarchuk@gmail.com>
Co-authored-by: Michel Loiseleur <97035654+mloiseleur@users.noreply.github.com>

controller/controller.go

@@ -37,7 +37,6 @@ import (
 var (
 	registryErrorsTotal = metrics.NewCounterWithOpts(
 		prometheus.CounterOpts{
-			Namespace: "external_dns",
 			Subsystem: "registry",
 			Name:      "errors_total",
 			Help:      "Number of Registry errors.",
@@ -45,7 +44,6 @@ var (
 	)
 	sourceErrorsTotal = metrics.NewCounterWithOpts(
 		prometheus.CounterOpts{
-			Namespace: "external_dns",
 			Subsystem: "source",
 			Name:      "errors_total",
 			Help:      "Number of Source errors.",
@@ -53,7 +51,6 @@ var (
 	)
 	sourceEndpointsTotal = metrics.NewGaugeWithOpts(
 		prometheus.GaugeOpts{
-			Namespace: "external_dns",
 			Subsystem: "source",
 			Name:      "endpoints_total",
 			Help:      "Number of Endpoints in all sources",
@@ -61,7 +58,6 @@ var (
 	)
 	registryEndpointsTotal = metrics.NewGaugeWithOpts(
 		prometheus.GaugeOpts{
-			Namespace: "external_dns",
 			Subsystem: "registry",
 			Name:      "endpoints_total",
 			Help:      "Number of Endpoints in the registry",
@@ -69,7 +65,6 @@ var (
 	)
 	lastSyncTimestamp = metrics.NewGaugeWithOpts(
 		prometheus.GaugeOpts{
-			Namespace: "external_dns",
 			Subsystem: "controller",
 			Name:      "last_sync_timestamp_seconds",
 			Help:      "Timestamp of last successful sync with the DNS provider",
@@ -77,7 +72,6 @@ var (
 	)
 	lastReconcileTimestamp = metrics.NewGaugeWithOpts(
 		prometheus.GaugeOpts{
-			Namespace: "external_dns",
 			Subsystem: "controller",
 			Name:      "last_reconcile_timestamp_seconds",
 			Help:      "Timestamp of last attempted sync with the DNS provider",
@@ -85,7 +79,6 @@ var (
 	)
 	controllerNoChangesTotal = metrics.NewCounterWithOpts(
 		prometheus.CounterOpts{
-			Namespace: "external_dns",
 			Subsystem: "controller",
 			Name:      "no_op_runs_total",
 			Help:      "Number of reconcile loops ending up with no changes on the DNS provider side.",
@@ -108,7 +101,6 @@ var (
 
 	registryRecords = metrics.NewGaugedVectorOpts(
 		prometheus.GaugeOpts{
-			Namespace: "external_dns",
 			Subsystem: "registry",
 			Name:      "records",
 			Help:      "Number of registry records partitioned by label name (vector).",
@@ -118,7 +110,6 @@ var (
 
 	sourceRecords = metrics.NewGaugedVectorOpts(
 		prometheus.GaugeOpts{
-			Namespace: "external_dns",
 			Subsystem: "source",
 			Name:      "records",
 			Help:      "Number of source records partitioned by label name (vector).",
@@ -128,7 +119,6 @@ var (
 
 	verifiedRecords = metrics.NewGaugedVectorOpts(
 		prometheus.GaugeOpts{
-			Namespace: "external_dns",
 			Subsystem: "controller",
 			Name:      "verified_records",
 			Help:      "Number of DNS records that exists both in source and registry (vector).",
@@ -138,7 +128,6 @@ var (
 
 	consecutiveSoftErrors = metrics.NewGaugeWithOpts(
 		prometheus.GaugeOpts{
-			Namespace: "external_dns",
 			Subsystem: "controller",
 			Name:      "consecutive_soft_errors",
 			Help:      "Number of consecutive soft errors in reconciliation loop.",

docs/monitoring/metrics.md

@@ -20,6 +20,7 @@ curl https://localhost:7979/metrics
 
 | Name                             | Metric Type | Subsystem   |  Help                                                 |
 |:---------------------------------|:------------|:------------|:------------------------------------------------------|
+| build_info | Gauge |  | A metric with a constant '1' value labeled with 'version' and 'revision' of external_dns and the 'go_version', 'os' and the 'arch' used the build. |
 | consecutive_soft_errors | Gauge | controller | Number of consecutive soft errors in reconciliation loop. |
 | last_reconcile_timestamp_seconds | Gauge | controller | Timestamp of last attempted sync with the DNS provider |
 | last_sync_timestamp_seconds | Gauge | controller | Timestamp of last successful sync with the DNS provider |

internal/gen/docs/metrics/main_test.go

@@ -37,7 +37,7 @@ func TestComputeMetrics(t *testing.T) {
 		t.Errorf("Expected not empty metrics registry, got %d", len(reg.Metrics))
 	}
 
-	assert.Len(t, reg.Metrics, 19)
+	assert.Len(t, reg.Metrics, 20)
 }
 
 func TestGenerateMarkdownTableRenderer(t *testing.T) {

pkg/metrics/metrics.go

@@ -17,25 +17,44 @@ limitations under the License.
 package metrics
 
 import (
-	"runtime"
+	"fmt"
 
 	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/common/version"
 	log "github.com/sirupsen/logrus"
 
 	cfg "sigs.k8s.io/external-dns/pkg/apis/externaldns"
 )
 
+const (
+	Namespace = "external_dns"
+)
+
 var (
 	RegisterMetric = NewMetricsRegister()
 )
 
+func init() {
+	RegisterMetric.MustRegister(NewGaugeFuncMetric(prometheus.GaugeOpts{
+		Namespace: Namespace,
+		Name:      "build_info",
+		Help: fmt.Sprintf(
+			"A metric with a constant '1' value labeled with 'version' and 'revision' of %s and the 'go_version', 'os' and the 'arch' used the build.",
+			Namespace,
+		),
+		ConstLabels: prometheus.Labels{
+			"version":    cfg.Version,
+			"revision":   version.GetRevision(),
+			"go_version": version.GoVersion,
+			"os":         version.GoOS,
+			"arch":       version.GoArch,
+		},
+	}))
+}
+
 func NewMetricsRegister() *MetricRegistry {
 	reg := prometheus.WrapRegistererWith(
-		prometheus.Labels{
+		prometheus.Labels{},
-			"version":    cfg.Version,
-			"arch":       runtime.GOARCH,
-			"go_version": runtime.Version(),
-		},
 		prometheus.DefaultRegisterer)
 	return &MetricRegistry{
 		Registerer: reg,
@@ -54,7 +73,7 @@ func NewMetricsRegister() *MetricRegistry {
 //	}
 func (m *MetricRegistry) MustRegister(cs IMetric) {
 	switch v := cs.(type) {
-	case CounterMetric, GaugeMetric, CounterVecMetric, GaugeVecMetric:
+	case CounterMetric, GaugeMetric, CounterVecMetric, GaugeVecMetric, GaugeFuncMetric:
 		if _, exists := m.mName[cs.Get().FQDN]; exists {
 			return
 		} else {
@@ -70,6 +89,8 @@ func (m *MetricRegistry) MustRegister(cs IMetric) {
 			m.Registerer.MustRegister(metric.Gauge)
 		case CounterVecMetric:
 			m.Registerer.MustRegister(metric.CounterVec)
+		case GaugeFuncMetric:
+			m.Registerer.MustRegister(metric.GaugeFunc)
 		}
 		log.Debugf("Register metric: %s", cs.Get().FQDN)
 	default:

pkg/metrics/models.go

@@ -88,6 +88,7 @@ func (g GaugeVecMetric) SetWithLabels(value float64, lvs ...string) {
 }
 
 func NewGaugeWithOpts(opts prometheus.GaugeOpts) GaugeMetric {
+	opts.Namespace = Namespace
 	return GaugeMetric{
 		Metric: Metric{
 			Type:      "gauge",
@@ -104,6 +105,7 @@ func NewGaugeWithOpts(opts prometheus.GaugeOpts) GaugeMetric {
 // NewGaugedVectorOpts creates a new GaugeVec based on the provided GaugeOpts and
 // partitioned by the given label names.
 func NewGaugedVectorOpts(opts prometheus.GaugeOpts, labelNames []string) GaugeVecMetric {
+	opts.Namespace = Namespace
 	return GaugeVecMetric{
 		Metric: Metric{
 			Type:      "gauge",
@@ -118,6 +120,7 @@ func NewGaugedVectorOpts(opts prometheus.GaugeOpts, labelNames []string) GaugeVe
 }
 
 func NewCounterWithOpts(opts prometheus.CounterOpts) CounterMetric {
+	opts.Namespace = Namespace
 	return CounterMetric{
 		Metric: Metric{
 			Type:      "counter",
@@ -132,6 +135,7 @@ func NewCounterWithOpts(opts prometheus.CounterOpts) CounterMetric {
 }
 
 func NewCounterVecWithOpts(opts prometheus.CounterOpts, labelNames []string) CounterVecMetric {
+	opts.Namespace = Namespace
 	return CounterVecMetric{
 		Metric: Metric{
 			Type:      "counter",
@@ -144,3 +148,31 @@ func NewCounterVecWithOpts(opts prometheus.CounterOpts, labelNames []string) Cou
 		CounterVec: prometheus.NewCounterVec(opts, labelNames),
 	}
 }
+
+type GaugeFuncMetric struct {
+	Metric
+	GaugeFunc prometheus.GaugeFunc
+}
+
+func (g GaugeFuncMetric) Get() *Metric {
+	return &g.Metric
+}
+
+func NewGaugeFuncMetric(opts prometheus.GaugeOpts) GaugeFuncMetric {
+	return GaugeFuncMetric{
+		Metric: Metric{
+			Type: "gauge",
+			Name: opts.Name,
+			FQDN: func() string {
+				if opts.Subsystem != "" {
+					return fmt.Sprintf("%s_%s", opts.Subsystem, opts.Name)
+				}
+				return opts.Name
+			}(),
+			Namespace: opts.Namespace,
+			Subsystem: opts.Subsystem,
+			Help:      opts.Help,
+		},
+		GaugeFunc: prometheus.NewGaugeFunc(opts, func() float64 { return 1 }),
+	}
+}

pkg/metrics/models_test.go

@@ -17,18 +17,17 @@ limitations under the License.
 package metrics
 
 import (
+	"reflect"
 	"testing"
 
-	dto "github.com/prometheus/client_model/go"
-
 	"github.com/prometheus/client_golang/prometheus"
+	dto "github.com/prometheus/client_model/go"
 	"github.com/stretchr/testify/assert"
 )
 
 func TestNewGaugeWithOpts(t *testing.T) {
 	opts := prometheus.GaugeOpts{
 		Name:      "test_gauge",
-		Namespace: "test_namespace",
 		Subsystem: "test_subsystem",
 		Help:      "This is a test gauge",
 	}
@@ -37,7 +36,7 @@ func TestNewGaugeWithOpts(t *testing.T) {
 
 	assert.Equal(t, "gauge", gaugeMetric.Type)
 	assert.Equal(t, "test_gauge", gaugeMetric.Name)
-	assert.Equal(t, "test_namespace", gaugeMetric.Namespace)
+	assert.Equal(t, Namespace, gaugeMetric.Namespace)
 	assert.Equal(t, "test_subsystem", gaugeMetric.Subsystem)
 	assert.Equal(t, "This is a test gauge", gaugeMetric.Help)
 	assert.Equal(t, "test_subsystem_test_gauge", gaugeMetric.FQDN)
@@ -47,7 +46,6 @@ func TestNewGaugeWithOpts(t *testing.T) {
 func TestNewCounterWithOpts(t *testing.T) {
 	opts := prometheus.CounterOpts{
 		Name:      "test_counter",
-		Namespace: "test_namespace",
 		Subsystem: "test_subsystem",
 		Help:      "This is a test counter",
 	}
@@ -56,7 +54,7 @@ func TestNewCounterWithOpts(t *testing.T) {
 
 	assert.Equal(t, "counter", counterMetric.Type)
 	assert.Equal(t, "test_counter", counterMetric.Name)
-	assert.Equal(t, "test_namespace", counterMetric.Namespace)
+	assert.Equal(t, Namespace, counterMetric.Namespace)
 	assert.Equal(t, "test_subsystem", counterMetric.Subsystem)
 	assert.Equal(t, "This is a test counter", counterMetric.Help)
 	assert.Equal(t, "test_subsystem_test_counter", counterMetric.FQDN)
@@ -77,7 +75,7 @@ func TestNewCounterVecWithOpts(t *testing.T) {
 
 	assert.Equal(t, "counter", counterVecMetric.Type)
 	assert.Equal(t, "test_counter_vec", counterVecMetric.Name)
-	assert.Equal(t, "test_namespace", counterVecMetric.Namespace)
+	assert.Equal(t, Namespace, counterVecMetric.Namespace)
 	assert.Equal(t, "test_subsystem", counterVecMetric.Subsystem)
 	assert.Equal(t, "This is a test counter vector", counterVecMetric.Help)
 	assert.Equal(t, "test_subsystem_test_counter_vec", counterVecMetric.FQDN)
@@ -113,3 +111,20 @@ func TestGaugeV_SetWithLabels(t *testing.T) {
 
 	assert.Len(t, m.Label, 2)
 }
+
+func TestNewBuildInfoCollector(t *testing.T) {
+	metric := NewGaugeFuncMetric(prometheus.GaugeOpts{
+		Namespace: Namespace,
+		Name:      "build_info",
+		ConstLabels: prometheus.Labels{
+			"version":   "0.0.1",
+			"goversion": "1.24",
+			"arch":      "arm64",
+		},
+	})
+
+	desc := metric.GaugeFunc.Desc()
+
+	assert.Equal(t, "external_dns_build_info", reflect.ValueOf(desc).Elem().FieldByName("fqName").String())
+	assert.Contains(t, desc.String(), "version=\"0.0.1\"")
+}

provider/cached_provider.go

@@ -31,7 +31,6 @@ import (
 var (
 	cachedRecordsCallsTotal = metrics.NewCounterVecWithOpts(
 		prometheus.CounterOpts{
-			Namespace: "external_dns",
 			Subsystem: "provider",
 			Name:      "cache_records_calls",
 			Help:      "Number of calls to the provider cache Records list.",
@@ -42,7 +41,6 @@ var (
 	)
 	cachedApplyChangesCallsTotal = metrics.NewCounterWithOpts(
 		prometheus.CounterOpts{
-			Namespace: "external_dns",
 			Subsystem: "provider",
 			Name:      "cache_apply_changes_calls",
 			Help:      "Number of calls to the provider cache ApplyChanges.",

provider/webhook/webhook.go

@@ -43,7 +43,6 @@ const (
 var (
 	recordsErrorsGauge = metrics.NewGaugeWithOpts(
 		prometheus.GaugeOpts{
-			Namespace: "external_dns",
 			Subsystem: "webhook_provider",
 			Name:      "records_errors_total",
 			Help:      "Errors with Records method",
@@ -51,7 +50,6 @@ var (
 	)
 	recordsRequestsGauge = metrics.NewGaugeWithOpts(
 		prometheus.GaugeOpts{
-			Namespace: "external_dns",
 			Subsystem: "webhook_provider",
 			Name:      "records_requests_total",
 			Help:      "Requests with Records method",
@@ -59,7 +57,6 @@ var (
 	)
 	applyChangesErrorsGauge = metrics.NewGaugeWithOpts(
 		prometheus.GaugeOpts{
-			Namespace: "external_dns",
 			Subsystem: "webhook_provider",
 			Name:      "applychanges_errors_total",
 			Help:      "Errors with ApplyChanges method",
@@ -67,7 +64,6 @@ var (
 	)
 	applyChangesRequestsGauge = metrics.NewGaugeWithOpts(
 		prometheus.GaugeOpts{
-			Namespace: "external_dns",
 			Subsystem: "webhook_provider",
 			Name:      "applychanges_requests_total",
 			Help:      "Requests with ApplyChanges method",
@@ -75,7 +71,6 @@ var (
 	)
 	adjustEndpointsErrorsGauge = metrics.NewGaugeWithOpts(
 		prometheus.GaugeOpts{
-			Namespace: "external_dns",
 			Subsystem: "webhook_provider",
 			Name:      "adjustendpoints_errors_total",
 			Help:      "Errors with AdjustEndpoints method",
@@ -83,7 +78,6 @@ var (
 	)
 	adjustEndpointsRequestsGauge = metrics.NewGaugeWithOpts(
 		prometheus.GaugeOpts{
-			Namespace: "external_dns",
 			Subsystem: "webhook_provider",
 			Name:      "adjustendpoints_requests_total",
 			Help:      "Requests with AdjustEndpoints method",