Add maintenance metric (#18703)

Author: WVerlaek

components/ws-manager-mk2/controllers/maintenance_controller.go

@@ -13,6 +13,7 @@ import (
 	"time"
 
 	"github.com/gitpod-io/gitpod/ws-manager/api/config"
+	"github.com/prometheus/client_golang/prometheus"
 	corev1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/types"
@@ -33,11 +34,16 @@ var (
 	lookupOnce sync.Once
 )
 
-func NewMaintenanceReconciler(c client.Client) (*MaintenanceReconciler, error) {
-	return &MaintenanceReconciler{
+func NewMaintenanceReconciler(c client.Client, reg prometheus.Registerer) (*MaintenanceReconciler, error) {
+	r := &MaintenanceReconciler{
 		Client:       c,
 		enabledUntil: nil,
-	}, nil
+	}
+
+	gauge := newMaintenanceEnabledGauge(r)
+	reg.MustRegister(gauge)
+
+	return r, nil
 }
 
 type MaintenanceReconciler struct {

components/ws-manager-mk2/controllers/metrics.go

@@ -10,6 +10,7 @@ import (
 	"time"
 
 	wsk8s "github.com/gitpod-io/gitpod/common-go/kubernetes"
+	"github.com/gitpod-io/gitpod/ws-manager-mk2/pkg/maintenance"
 	workspacev1 "github.com/gitpod-io/gitpod/ws-manager/api/crd/v1"
 	"github.com/go-logr/logr"
 	lru "github.com/hashicorp/golang-lru"
@@ -18,6 +19,7 @@ import (
 )
 
 const (
+	maintenanceEnabled            string = "maintenance_enabled"
 	workspaceStartupSeconds       string = "workspace_startup_seconds"
 	workspaceStartFailuresTotal   string = "workspace_starts_failure_total"
 	workspaceFailuresTotal        string = "workspace_failure_total"
@@ -399,3 +401,36 @@ func (tsv *timeoutSettingsVec) Collect(ch chan<- prometheus.Metric) {
 		ch <- metric
 	}
 }
+
+type maintenanceEnabledGauge struct {
+	name        string
+	desc        *prometheus.Desc
+	maintenance maintenance.Maintenance
+}
+
+func newMaintenanceEnabledGauge(m maintenance.Maintenance) *maintenanceEnabledGauge {
+	name := prometheus.BuildFQName(metricsNamespace, metricsWorkspaceSubsystem, maintenanceEnabled)
+	return &maintenanceEnabledGauge{
+		name:        name,
+		desc:        prometheus.NewDesc(name, "Whether the cluster is in maintenance mode", nil, prometheus.Labels(map[string]string{})),
+		maintenance: m,
+	}
+}
+
+func (m *maintenanceEnabledGauge) Describe(ch chan<- *prometheus.Desc) {
+	ch <- m.desc
+}
+
+func (m *maintenanceEnabledGauge) Collect(ch chan<- prometheus.Metric) {
+	var value float64
+	if m.maintenance.IsEnabled(context.Background()) {
+		value = 1
+	}
+
+	metric, err := prometheus.NewConstMetric(m.desc, prometheus.GaugeValue, value)
+	if err != nil {
+		return
+	}
+
+	ch <- metric
+}

components/ws-manager-mk2/main.go

@@ -137,7 +137,7 @@ func main() {
 
 	mgrCtx := ctrl.SetupSignalHandler()
 
-	maintenanceReconciler, err := controllers.NewMaintenanceReconciler(mgr.GetClient())
+	maintenanceReconciler, err := controllers.NewMaintenanceReconciler(mgr.GetClient(), metrics.Registry)
 	if err != nil {
 		setupLog.Error(err, "unable to create maintenance controller", "controller", "Maintenance")
 		os.Exit(1)