stackrox · parametalol · Jun 20, 2025
diff --git a/central/metrics/custom_registry.go b/central/metrics/custom_registry.go
@@ -0,0 +1,71 @@
+package metrics
+
+import (
+	"strings"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/stackrox/rox/pkg/metrics"
+	"github.com/stackrox/rox/pkg/sync"
+)
+
+/*
+Custom Prometheus metrics are user facing metrics, served on the API endpoint.
+The metrics are configured via the private section of the 'config' API.
+
+A metric is configured with a list of labels supported by the metric tracker.
+
+Metrics are immutable. To change anything, the metric has to be deleted and
+recreated with separate requests.
+*/
+
+//go:generate mockgen-wrapper
+type CustomRegistry interface {
+	RegisterMetric(metricName string, category string, period time.Duration, labels []string) error
+	UnregisterMetric(metricName string) bool
+	SetTotal(metricName string, labels prometheus.Labels, total int)
+}
+
+type customRegistry struct {
+	prometheus.Registerer
+	gauges sync.Map // map[metricName string]*prometheus.GaugeVec
+}
+
+// MakeCustomRegistry is a CustomRegistry factory.
+func MakeCustomRegistry() CustomRegistry {
+	return &customRegistry{
+		Registerer: prometheus.NewRegistry(),
+	}
+}
+
+var _ CustomRegistry = (*customRegistry)(nil)
+
+// UnregisterMetric unregister the given metric by name.
+func (cr *customRegistry) UnregisterMetric(metricName string) bool {
+	if gauge, loaded := cr.gauges.LoadAndDelete(metricName); loaded {
+		return cr.Unregister(gauge.(*prometheus.GaugeVec))
+	}
+	return false
+}
+
+// RegisterMetric registers a user-defined aggregated metric.
+func (cr *customRegistry) RegisterMetric(metricName string, category string, period time.Duration, labels []string) error {
+	gauge := prometheus.NewGaugeVec(prometheus.GaugeOpts{
+		Namespace: metrics.PrometheusNamespace,
+		Subsystem: metrics.CentralSubsystem.String(),
+		Name:      metricName,
+		Help: "The total number of " + category + " aggregated by " + strings.Join(labels, ",") +
+			" and gathered every " + period.String(),
+	}, labels)
+	if _, loaded := cr.gauges.LoadOrStore(metricName, gauge); !loaded {
+		return cr.Register(gauge)
+	}
+	return nil
+}
+
+// SetTotal sets the value to the gauge of a metric.
+func (cr *customRegistry) SetTotal(metricName string, labels prometheus.Labels, total int) {
+	if gauge, ok := cr.gauges.Load(metricName); ok {
+		gauge.(*prometheus.GaugeVec).With(labels).Set(float64(total))
+	}
+}
diff --git a/central/metrics/custom_registry_test.go b/central/metrics/custom_registry_test.go
@@ -0,0 +1,49 @@
+package metrics
+
+import (
+	"testing"
+	"time"
+
+	"github.com/pkg/errors"
+	"github.com/prometheus/client_golang/prometheus"
+	dto "github.com/prometheus/client_model/go"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestMakeCustomRegistry(t *testing.T) {
+	cr1 := MakeCustomRegistry()
+	cr2 := MakeCustomRegistry()
+	assert.NotSame(t, cr1, cr2)
+
+	assert.NoError(t, cr1.RegisterMetric("test", "test", 10*time.Minute, []string{"Test1", "Test2"}))
+	assert.NoError(t, cr1.RegisterMetric("test", "test", 10*time.Minute, []string{"Test1", "Test2"}))
+	assert.NoError(t, cr2.RegisterMetric("test", "test", 10*time.Minute, []string{"Test1", "Test2"}))
+
+	cr1.SetTotal("test", map[string]string{"Test1": "value1", "Test2": "value2"}, 42)
+	cr2.SetTotal("test", map[string]string{"Test1": "value1", "Test2": "value2"}, 24)
+
+	getMetricValue := func(registry CustomRegistry, metricName string) (float64, error) {
+		metricValue := &dto.Metric{}
+		gauge, ok := registry.(*customRegistry).gauges.Load(metricName)
+		if !ok {
+			return 0, errors.New("no such metric")
+		}
+		err := gauge.(*prometheus.GaugeVec).WithLabelValues("value1", "value2").Write(metricValue)
+		if err != nil {
+			return 0, err
+		}
+		return metricValue.GetGauge().GetValue(), nil
+	}
+
+	value, err := getMetricValue(cr1, "test")
+	assert.NoError(t, err)
+	assert.Equal(t, float64(42), value)
+
+	value, err = getMetricValue(cr2, "test")
+	assert.NoError(t, err)
+	assert.Equal(t, float64(24), value)
+
+	assert.True(t, cr1.UnregisterMetric("test"))
+	assert.False(t, cr1.UnregisterMetric("test"))
+	assert.True(t, cr2.UnregisterMetric("test"))
+}
diff --git a/central/metrics/mocks/custom_registry.go b/central/metrics/mocks/custom_registry.go