Approval controller example1

cmd/metric-app/main.go

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+package main
+
+import (
+	"net/http"
+	"os"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+func main() {
+	// Get cluster and workload information from environment variables
+	clusterName := os.Getenv("CLUSTER_NAME")
+	if clusterName == "" {
+		clusterName = "unknown"
+	}
+
+	workloadName := os.Getenv("WORKLOAD_NAME")
+	if workloadName == "" {
+		workloadName = "unknown"
+	}
+
+	// Define a simple gauge metric for health with labels
+	workloadHealth := prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name: "workload_health",
+			Help: "Indicates if the workload is healthy (1=healthy, 0=unhealthy)",
+		},
+		[]string{"cluster_name", "workload_name"},
+	)
+
+	// Set it to 1 (healthy) with labels
+	workloadHealth.WithLabelValues(clusterName, workloadName).Set(1)
+
+	// Register metric with Prometheus default registry
+	prometheus.MustRegister(workloadHealth)
+
+	// Expose metrics endpoint
+	http.Handle("/metrics", promhttp.Handler())
+
+	// Start HTTP server
+	http.ListenAndServe(":8080", nil)
+}

docker/metric-app.Dockerfile

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+# Build stage
+FROM golang:1.24-alpine AS builder
+WORKDIR /workspace
+# Copy go mod files
+COPY go.mod go.sum ./
+RUN go mod download
+# Copy source code
+COPY cmd/metric-app/ ./cmd/metric-app/
+# Build the application
+RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o metric-app ./cmd/metric-app/main.go
+
+# Run stage
+FROM alpine:3.18
+WORKDIR /app
+COPY --from=builder /workspace/metric-app .
+EXPOSE 8080
+CMD ["./metric-app"]

examples/prometheus/README.md

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+# Prometheus Setup for MetricCollector Testing
+
+This directory contains manifests to deploy Prometheus for testing the MetricCollector controller with the sample-metric-app.
+
+## Prerequisites
+
+- Kind cluster running (e.g., cluster-1, cluster-2, or cluster-3)
+- `test-ns` namespace exists
+- `ghcr.io/metric-app:6d6cd69` image loaded into the cluster
+
+## Quick Start
+
+```bash
+# Switch to target cluster
+kubectl config use-context kind-cluster-1
+
+# Create namespace if needed
+kubectl create namespace test-ns --dry-run=client -o yaml | kubectl apply -f -
+
+# Deploy Prometheus
+kubectl apply -f rbac.yaml
+kubectl apply -f configmap.yaml
+kubectl apply -f deployment.yaml
+kubectl apply -f service.yaml
+
+# Deploy sample-metric-app (from parent examples directory)
+kubectl apply -f ../sample-metric-app.yaml
+
+# Wait for pods to be ready
+kubectl wait --for=condition=ready pod -l app=prometheus -n test-ns --timeout=60s
+kubectl wait --for=condition=ready pod -l app=sample-metric-app -n test-ns --timeout=60s
+```
+
+## Verify Setup
+
+### Check Prometheus is scraping metrics
+
+```bash
+# Port-forward Prometheus
+kubectl port-forward -n test-ns svc/prometheus 9090:9090
+```
+
+Open http://localhost:9090 in your browser and:
+1. Go to Status > Targets - you should see `sample-metric-app` pod listed
+2. Go to Graph and query: `workload_health` - you should see metrics
+
+### Test with prometheus-test tool
+
+```bash
+# In another terminal (while port-forward is running)
+cd tools/prometheus-test
+go build -o prometheus-test main.go
+./prometheus-test http://localhost:9090 workload_health
+
+# Or with namespace filter
+./prometheus-test http://localhost:9090 workload_health test-ns
+```
+
+Expected output:
+```
+Querying Prometheus at: http://localhost:9090
+Query: workload_health{namespace="test-ns"}
+
+Status: success
+Result Type: vector
+Number of results: 1
+
+Result 1:
+  Labels:
+    app: sample-metric-app
+    namespace: test-ns
+    pod: sample-metric-app-xxxxx
+  Timestamp: 1732032000.0
+  Value: 1
+```
+
+## Configuration Details
+
+### Prometheus ConfigMap
+The Prometheus configuration discovers pods with these annotations:
+- `prometheus.io/scrape: "true"` - Enable scraping
+- `prometheus.io/port: "8080"` - Port to scrape
+- `prometheus.io/path: "/metrics"` - Metrics endpoint path
+
+The sample-metric-app already has these annotations configured.
+
+### RBAC
+Prometheus needs permissions to discover and scrape pods. The `rbac.yaml` creates:
+- ServiceAccount for Prometheus
+- ClusterRole with pod discovery permissions
+- ClusterRoleBinding to grant permissions
+
+## Testing MetricCollector
+
+Once Prometheus is running, create a MetricCollector CR:
+
+```bash
+kubectl apply -f - <<EOF
+apiVersion: placement.kubernetes-fleet.io/v1beta1
+kind: MetricCollector
+metadata:
+  name: sample-collector
+  namespace: test-ns
+spec:
+  workloadSelector:
+    labelSelector:
+      matchLabels:
+        app: sample-metric-app
+    namespaces:
+      - test-ns
+  metricsEndpoint:
+    sourceType: prometheus
+    prometheusEndpoint:
+      url: http://prometheus.test-ns.svc.cluster.local:9090
+  collectionInterval: "30s"
+  metricsToCollect:
+    - workload_health

examples/prometheus/configmap.yaml

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+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: prometheus-config
+  namespace: test-ns
+data:
+  prometheus.yml: |
+    global:
+      scrape_interval: 15s
+      evaluation_interval: 15s
+
+    scrape_configs:
+      - job_name: 'kubernetes-pods'
+        kubernetes_sd_configs:
+          - role: pod
+            namespaces:
+              names:
+                - test-ns
+        relabel_configs:
+          # Only scrape pods with prometheus.io/scrape annotation
+          - source_labels: [__meta_kubernetes_pod_annotation_prometheus_io_scrape]
+            action: keep
+            regex: true
+          # Use the port from prometheus.io/port annotation or default pod IP
+          - source_labels: [__address__, __meta_kubernetes_pod_annotation_prometheus_io_port]
+            action: replace
+            regex: ([^:]+)(?::\d+)?;(\d+)
+            replacement: $1:$2
+            target_label: __address__
+          # Use the path from prometheus.io/path annotation or default /metrics
+          - source_labels: [__meta_kubernetes_pod_annotation_prometheus_io_path]
+            action: replace
+            target_label: __metrics_path__
+            regex: (.+)
+          # Add pod metadata as labels
+          - source_labels: [__meta_kubernetes_namespace]
+            target_label: namespace
+          - source_labels: [__meta_kubernetes_pod_name]
+            target_label: pod
+          - source_labels: [__meta_kubernetes_pod_label_app]
+            target_label: app
+          # Add CLUSTER_NAME and WORKLOAD_NAME from env vars if present
+          - action: labelmap
+            regex: __meta_kubernetes_pod_label_(.+)

examples/prometheus/deployment.yaml

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+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: prometheus
+  namespace: test-ns
+  labels:
+    app: prometheus
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: prometheus
+  template:
+    metadata:
+      labels:
+        app: prometheus
+    spec:
+      serviceAccountName: prometheus
+      containers:
+        - name: prometheus
+          image: prom/prometheus:v2.47.0
+          args:
+            - '--config.file=/etc/prometheus/prometheus.yml'
+            - '--storage.tsdb.path=/prometheus'
+            - '--web.console.libraries=/usr/share/prometheus/console_libraries'
+            - '--web.console.templates=/usr/share/prometheus/consoles'
+            - '--web.enable-lifecycle'
+          ports:
+            - name: web
+              containerPort: 9090
+          volumeMounts:
+            - name: prometheus-config
+              mountPath: /etc/prometheus
+            - name: prometheus-storage
+              mountPath: /prometheus
+          resources:
+            requests:
+              cpu: 100m
+              memory: 256Mi
+            limits:
+              cpu: 500m
+              memory: 512Mi
+      volumes:
+        - name: prometheus-config
+          configMap:
+            name: prometheus-config
+        - name: prometheus-storage
+          emptyDir: {}

examples/prometheus/rbac.yaml

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+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: prometheus
+  namespace: test-ns
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRole
+metadata:
+  name: prometheus
+rules:
+  - apiGroups: [""]
+    resources:
+      - nodes
+      - nodes/proxy
+      - services
+      - endpoints
+      - pods
+    verbs: ["get", "list", "watch"]
+  - apiGroups:
+      - extensions
+    resources:
+      - ingresses
+    verbs: ["get", "list", "watch"]
+  - nonResourceURLs: ["/metrics"]
+    verbs: ["get"]
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRoleBinding
+metadata:
+  name: prometheus
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: ClusterRole
+  name: prometheus
+subjects:
+  - kind: ServiceAccount
+    name: prometheus
+    namespace: test-ns

examples/prometheus/service.yaml

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+apiVersion: v1
+kind: Service
+metadata:
+  name: prometheus
+  namespace: test-ns
+  labels:
+    app: prometheus
+spec:
+  type: ClusterIP
+  ports:
+    - name: web
+      port: 9090
+      targetPort: 9090
+      protocol: TCP
+  selector:
+    app: prometheus

examples/sample-metric-app-crp.yaml

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+apiVersion: placement.kubernetes-fleet.io/v1beta1
+kind: ClusterResourcePlacement
+metadata:
+  name: sample-metric-app
+spec:
+  resourceSelectors:
+    - group: ""
+      version: v1
+      kind: Namespace
+      name: test-ns
+    - group: "rbac.authorization.k8s.io"
+      version: v1
+      kind: ClusterRole
+      name: prometheus
+    - group: "rbac.authorization.k8s.io"
+      version: v1
+      kind: ClusterRoleBinding
+      name: prometheus
+  policy:
+    placementType: PickAll
+  strategy:
+    type: RollingUpdate