Provide scale-set listener metrics (#2559)

Co-authored-by: Tingluo Huang <tingluohuang@github.com>
Co-authored-by: Bassem Dghaidi <568794+Link-@users.noreply.github.com>

controllers/actions.github.com/metrics/metrics.go

@@ -0,0 +1,92 @@
+package metrics
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+	"sigs.k8s.io/controller-runtime/pkg/metrics"
+)
+
+var githubScaleSetControllerSubsystem = "gha_controller"
+
+var labels = []string{
+	"name",
+	"namespace",
+	"repository",
+	"organization",
+	"enterprise",
+}
+
+type CommonLabels struct {
+	Name         string
+	Namespace    string
+	Repository   string
+	Organization string
+	Enterprise   string
+}
+
+func (l *CommonLabels) labels() prometheus.Labels {
+	return prometheus.Labels{
+		"name":         l.Name,
+		"namespace":    l.Namespace,
+		"repository":   l.Repository,
+		"organization": l.Organization,
+		"enterprise":   l.Enterprise,
+	}
+}
+
+var (
+	pendingEphemeralRunners = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Subsystem: githubScaleSetControllerSubsystem,
+			Name:      "pending_ephemeral_runners",
+			Help:      "Number of ephemeral runners in a pending state.",
+		},
+		labels,
+	)
+	runningEphemeralRunners = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Subsystem: githubScaleSetControllerSubsystem,
+			Name:      "running_ephemeral_runners",
+			Help:      "Number of ephemeral runners in a running state.",
+		},
+		labels,
+	)
+	failedEphemeralRunners = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Subsystem: githubScaleSetControllerSubsystem,
+			Name:      "failed_ephemeral_runners",
+			Help:      "Number of ephemeral runners in a failed state.",
+		},
+		labels,
+	)
+	runningListeners = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Subsystem: githubScaleSetControllerSubsystem,
+			Name:      "running_listeners",
+			Help:      "Number of listeners in a running state.",
+		},
+		labels,
+	)
+)
+
+func RegisterMetrics() {
+	metrics.Registry.MustRegister(
+		pendingEphemeralRunners,
+		runningEphemeralRunners,
+		failedEphemeralRunners,
+		runningListeners,
+	)
+}
+
+func SetEphemeralRunnerCountsByStatus(commonLabels CommonLabels, pending, running, failed int) {
+	pendingEphemeralRunners.With(commonLabels.labels()).Set(float64(pending))
+	runningEphemeralRunners.With(commonLabels.labels()).Set(float64(running))
+	failedEphemeralRunners.With(commonLabels.labels()).Set(float64(failed))
+}
+
+func AddRunningListener(commonLabels CommonLabels) {
+	runningListeners.With(commonLabels.labels()).Set(1)
+}
+
+func SubRunningListener(commonLabels CommonLabels) {
+	runningListeners.With(commonLabels.labels()).Set(0)
+}