fix(heartbeat): add nil check in heartbeat's metricscardinality

Signed-off-by: Alex Castilio dos Santos <[email protected]>

pkg/telemetry/telemetry.go

@@ -5,6 +5,7 @@ package telemetry
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"maps"
 	"os"
@@ -18,6 +19,7 @@ import (
 	"github.com/microsoft/ApplicationInsights-Go/appinsights/contracts"
 	"github.com/microsoft/retina/pkg/exporter"
 	"github.com/microsoft/retina/pkg/log"
+	"github.com/prometheus/client_golang/prometheus"
 	io_prometheus_client "github.com/prometheus/client_model/go"
 )
 
@@ -26,6 +28,8 @@ var (
 	version string
 	mbShift uint64 = 20
 
+	ErrorNilCombinedGatherer = errors.New("exporter.CombinedGatherer is nil")
+
 	// property keys
 	kernelversion = "kernelversion"
 	sysmem        = "sysmem"
@@ -178,7 +182,7 @@ func (t *TelemetryClient) heartbeat(ctx context.Context) {
 		t.trackWarning(err, "failed to get cpu usage")
 	}
 
-	metricscardinality, err := metricsCardinality()
+	metricscardinality, err := metricsCardinality(exporter.CombinedGatherer)
 	if err != nil {
 		t.trackWarning(err, "failed to get metrics cardinality")
 	}
@@ -189,8 +193,12 @@ func (t *TelemetryClient) heartbeat(ctx context.Context) {
 	maps.Copy(props, t.profile.GetMemoryUsage())
 	t.TrackEvent("heartbeat", props)
 }
-func metricsCardinality() (int, error) {
-	metricFamilies, err := exporter.CombinedGatherer.Gather()
+func metricsCardinality(gatherer prometheus.Gatherer) (int, error) {
+	if gatherer == nil {
+		return 0, fmt.Errorf("failed to get metrics Gatherer: %w", ErrorNilCombinedGatherer)
+	}
+
+	metricFamilies, err := gatherer.Gather()
 	if err != nil {
 		return 0, fmt.Errorf("failed to gather metrics: %w", err)
 	}
@@ -203,23 +211,44 @@ func metricsCardinality() (int, error) {
 		case io_prometheus_client.MetricType_HISTOGRAM:
 			metrics := mf.GetMetric()
 			for _, m := range metrics {
-				metricscardinality += len(m.GetHistogram().GetBucket()) + 3 // +3 for le="+Inf", _sum and _count
+				histogram := m.GetHistogram()
+				if histogram != nil {
+					buckets := histogram.GetBucket()
+					if buckets != nil {
+						metricscardinality += len(buckets) + 3 // +3 for le="+Inf", _sum and _count
+					}
+				}
 			}
 
 		case io_prometheus_client.MetricType_GAUGE_HISTOGRAM:
 			metrics := mf.GetMetric()
 			for _, m := range metrics {
-				metricscardinality += len(m.GetHistogram().GetBucket()) + 3 // +3 for le="+Inf", _sum and _count
+				histogram := m.GetHistogram()
+				if histogram != nil {
+					buckets := histogram.GetBucket()
+					if buckets != nil {
+						metricscardinality += len(buckets) + 3 // +3 for le="+Inf", _sum and _count
+					}
+				}
 			}
 
 		case io_prometheus_client.MetricType_SUMMARY:
 			metrics := mf.GetMetric()
 			for _, m := range metrics {
-				metricscardinality += len(m.GetSummary().GetQuantile()) + 2 // +2 for _sum and _count
+				summary := m.GetSummary()
+				if summary != nil {
+					quantiles := summary.GetQuantile()
+					if quantiles != nil {
+						metricscardinality += len(quantiles) + 2 // +2 for _sum and _count
+					}
+				}
 			}
 
 		default:
-			metricscardinality += len(mf.GetMetric())
+			metrics := mf.GetMetric()
+			if metrics != nil {
+				metricscardinality += len(metrics)
+			}
 
 		}
 	}

pkg/telemetry/telemetry_test.go

@@ -11,6 +11,8 @@ import (
 	"sync"
 	"testing"
 
+	"github.com/prometheus/client_golang/prometheus"
+	io_prometheus_client "github.com/prometheus/client_model/go"
 	"github.com/stretchr/testify/require"
 )
 
@@ -97,6 +99,175 @@ func TestHeartbeat(t *testing.T) {
 	}
 }
 
+func TestMetricsCardinality_nilCombinedGatherer(t *testing.T) {
+	var gatherer prometheus.Gatherer
+
+	t.Run("Combined Gatherer is nil", func(t *testing.T) {
+		m, err := metricsCardinality(gatherer)
+		require.Error(t, err)
+		require.Equal(t, 0, m)
+	})
+}
+
+type tGatherer struct {
+	mf []*io_prometheus_client.MetricFamily
+}
+
+func (t *tGatherer) Gather() ([]*io_prometheus_client.MetricFamily, error) {
+	return t.mf, nil
+}
+
+func TestMetricsCardinality(t *testing.T) {
+	counterType := io_prometheus_client.MetricType_COUNTER
+	histogramType := io_prometheus_client.MetricType_HISTOGRAM
+	gaugeHistogramType := io_prometheus_client.MetricType_GAUGE_HISTOGRAM
+	summaryType := io_prometheus_client.MetricType_SUMMARY
+
+	simpleCounter := prometheus.NewCounter(prometheus.CounterOpts{ //nolint:promlinter // its a test
+		Name: "test_counter",
+		Help: "test counter",
+	})
+
+	histogram3buckets := prometheus.NewHistogram(prometheus.HistogramOpts{ //nolint:promlinter // its a test
+		Name:    "3buckets_histogram",
+		Help:    "test histogram",
+		Buckets: []float64{1, 2, 3},
+	})
+
+	histogram5buckets := prometheus.NewHistogram(prometheus.HistogramOpts{ //nolint:promlinter // its a test
+		Name:    "5buckets_histogram",
+		Help:    "test histogram",
+		Buckets: []float64{1, 2, 3, 4, 5},
+	})
+	summary := prometheus.NewSummary(prometheus.SummaryOpts{ //nolint:promlinter // its a test
+		Name:       "test_summary",
+		Help:       "test summary",
+		Objectives: map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001},
+	})
+
+	outputCounter := io_prometheus_client.Metric{}
+	err := simpleCounter.Write(&outputCounter)
+	require.NoError(t, err)
+	testCounter := io_prometheus_client.MetricFamily{
+		Type: &counterType,
+		Metric: []*io_prometheus_client.Metric{
+			&outputCounter,
+		},
+	}
+
+	outputHistogram3Buckets := io_prometheus_client.Metric{}
+	err = histogram3buckets.Write(&outputHistogram3Buckets)
+	require.NoError(t, err)
+	test3BucketsHistogram := io_prometheus_client.MetricFamily{
+		Type: &histogramType,
+		Metric: []*io_prometheus_client.Metric{
+			&outputHistogram3Buckets,
+		},
+	}
+
+	outputHistogram5Buckets := io_prometheus_client.Metric{}
+	err = histogram5buckets.Write(&outputHistogram5Buckets)
+	require.NoError(t, err)
+	test5BucketsGaugeHistogram := io_prometheus_client.MetricFamily{
+		Type: &gaugeHistogramType,
+		Metric: []*io_prometheus_client.Metric{
+			&outputHistogram5Buckets,
+		},
+	}
+
+	outputSummary := io_prometheus_client.Metric{}
+	err = summary.Write(&outputSummary)
+	require.NoError(t, err)
+	testSummary := io_prometheus_client.MetricFamily{
+		Type: &summaryType,
+		Metric: []*io_prometheus_client.Metric{
+			&outputSummary,
+		},
+	}
+
+	testcases := []struct {
+		name                string
+		mf                  []*io_prometheus_client.MetricFamily
+		expectedCardinality int
+	}{
+		{
+			"Simple Counter",
+			[]*io_prometheus_client.MetricFamily{&testCounter},
+			1,
+		},
+		{
+			"3 Buckets Histogram",
+			[]*io_prometheus_client.MetricFamily{&test3BucketsHistogram},
+			6,
+		},
+		{
+			"5 Buckets Gauge Histogram",
+			[]*io_prometheus_client.MetricFamily{&test5BucketsGaugeHistogram},
+			8,
+		},
+		{
+			"Summary",
+			[]*io_prometheus_client.MetricFamily{&testSummary},
+			5,
+		},
+	}
+	for _, tc := range testcases {
+		t.Run(tc.name, func(t *testing.T) {
+			testGatherer := tGatherer{
+				mf: tc.mf,
+			}
+			gotCardinality, err := metricsCardinality(&testGatherer)
+			require.NoError(t, err)
+			require.Equal(t, tc.expectedCardinality, gotCardinality)
+		})
+	}
+}
+
+func TestMetricsCardinality_NilHistogram(t *testing.T) {
+	histogramType := io_prometheus_client.MetricType_HISTOGRAM
+	gaugeHistogramType := io_prometheus_client.MetricType_GAUGE_HISTOGRAM
+	summaryType := io_prometheus_client.MetricType_SUMMARY
+
+	nilHistogram := io_prometheus_client.MetricFamily{
+		Type: &histogramType,
+		Metric: []*io_prometheus_client.Metric{
+			{
+				Histogram: nil,
+			},
+		},
+	}
+	nilGaugeHistogram := io_prometheus_client.MetricFamily{
+		Type: &gaugeHistogramType,
+		Metric: []*io_prometheus_client.Metric{
+			{
+				Histogram: nil,
+			},
+		},
+	}
+	nilSummary := io_prometheus_client.MetricFamily{
+		Type: &summaryType,
+		Metric: []*io_prometheus_client.Metric{
+			{
+				Summary: nil,
+			},
+		},
+	}
+
+	testGatherer := tGatherer{
+		mf: []*io_prometheus_client.MetricFamily{
+			&nilHistogram,
+			&nilGaugeHistogram,
+			&nilSummary,
+		},
+	}
+
+	t.Run("Nil Histogram", func(t *testing.T) {
+		m, err := metricsCardinality(&testGatherer)
+		require.NoError(t, err)
+		require.Equal(t, 0, m)
+	})
+}
+
 func TestTelemetryClient_StopPerf(t *testing.T) {
 	type fields struct {
 		properties map[string]string