Add ControllerRing state exporter

Author: timebertt

pkg/metrics/add.go

@@ -28,6 +28,10 @@ const Namespace = "controller_sharding"
 
 // AddToManager adds all metrics exporters for sharding objects to the manager.
 func AddToManager(mgr manager.Manager) error {
+	if err := ControllerRingExporter.AddToManager(mgr); err != nil {
+		return fmt.Errorf("failed to add ControllerRing exporter: %w", err)
+	}
+
 	if err := ShardExporter.AddToManager(mgr); err != nil {
 		return fmt.Errorf("failed to add shard exporter: %w", err)
 	}

pkg/metrics/controllerring.go

@@ -0,0 +1,89 @@
+/*
+Copyright 2025 Tim Ebert.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package metrics
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+
+	shardingv1alpha1 "github.com/timebertt/kubernetes-controller-sharding/pkg/apis/sharding/v1alpha1"
+	"github.com/timebertt/kubernetes-controller-sharding/pkg/metrics/exporter"
+)
+
+var ControllerRingExporter = exporter.Exporter[*shardingv1alpha1.ControllerRing, *shardingv1alpha1.ControllerRingList]{
+	Namespace: Namespace,
+	Subsystem: "controllerring",
+
+	StaticLabelKeys: []string{"controllerring", "uid"},
+	GenerateStaticLabelValues: func(controllerRing *shardingv1alpha1.ControllerRing) []string {
+		return []string{controllerRing.Name, string(controllerRing.UID)}
+	},
+
+	Metrics: []exporter.Metric[*shardingv1alpha1.ControllerRing]{
+		{
+			Name: "metadata_generation",
+			Help: "The generation of a ControllerRing",
+
+			Generate: func(desc *prometheus.Desc, controllerRing *shardingv1alpha1.ControllerRing, staticLabelValues []string, ch chan<- prometheus.Metric) {
+				ch <- prometheus.MustNewConstMetric(
+					desc,
+					prometheus.GaugeValue,
+					float64(controllerRing.Generation),
+					staticLabelValues...,
+				)
+			},
+		},
+		{
+			Name: "observed_generation",
+			Help: "The latest generation observed by the ControllerRing controller",
+
+			Generate: func(desc *prometheus.Desc, controllerRing *shardingv1alpha1.ControllerRing, staticLabelValues []string, ch chan<- prometheus.Metric) {
+				ch <- prometheus.MustNewConstMetric(
+					desc,
+					prometheus.GaugeValue,
+					float64(controllerRing.Status.ObservedGeneration),
+					staticLabelValues...,
+				)
+			},
+		},
+		{
+			Name: "status_shards",
+			Help: "The ControllerRing's total number of shards observed by the ControllerRing controller",
+
+			Generate: func(desc *prometheus.Desc, controllerRing *shardingv1alpha1.ControllerRing, staticLabelValues []string, ch chan<- prometheus.Metric) {
+				ch <- prometheus.MustNewConstMetric(
+					desc,
+					prometheus.GaugeValue,
+					float64(controllerRing.Status.Shards),
+					staticLabelValues...,
+				)
+			},
+		},
+		{
+			Name: "status_available_shards",
+			Help: "The ControllerRing's number of available shards observed by the ControllerRing controller",
+
+			Generate: func(desc *prometheus.Desc, controllerRing *shardingv1alpha1.ControllerRing, staticLabelValues []string, ch chan<- prometheus.Metric) {
+				ch <- prometheus.MustNewConstMetric(
+					desc,
+					prometheus.GaugeValue,
+					float64(controllerRing.Status.AvailableShards),
+					staticLabelValues...,
+				)
+			},
+		},
+	},
+}