Add Patch to give optional option to enable ServiceMonitor to use cert-manager-managed serving-cert with TLS verification

Adds a patch to configure ServiceMonitor with  `insecureSkipVerify: false`  to ensure TLS verification using cert-manager certificates. Updates documentation and corrects misaligned comments.

Author: camilamacedo86

.github/workflows/test-e2e-samples.yml

@@ -41,7 +41,7 @@ jobs:
         run: |
           KUSTOMIZATION_FILE_PATH="testdata/project-v4/config/default/kustomization.yaml"
           sed -i '25s/^#//' $KUSTOMIZATION_FILE_PATH
-          sed -i '50,177s/^#//' $KUSTOMIZATION_FILE_PATH
+          sed -i '55,182s/^#//' $KUSTOMIZATION_FILE_PATH
           cd testdata/project-v4/
           go mod tidy
 
@@ -82,8 +82,8 @@ jobs:
           sed -i '25s/^#//' $KUSTOMIZATION_FILE_PATH
           # Uncomment only ValidatingWebhookConfiguration
           # from cert-manager replaces
-          sed -i '50,116s/^#//' $KUSTOMIZATION_FILE_PATH
-          sed -i '148,177s/^#//' $KUSTOMIZATION_FILE_PATH
+          sed -i '55,121s/^#//' $KUSTOMIZATION_FILE_PATH
+          sed -i '153,182s/^#//' $KUSTOMIZATION_FILE_PATH
           cd testdata/project-v4-with-plugins/
           go mod tidy
 
@@ -122,7 +122,7 @@ jobs:
         run: |
           KUSTOMIZATION_FILE_PATH="testdata/project-v4-multigroup/config/default/kustomization.yaml"
           sed -i '25s/^#//' $KUSTOMIZATION_FILE_PATH
-          sed -i '50,177s/^#//' $KUSTOMIZATION_FILE_PATH
+          sed -i '55,182s/^#//' $KUSTOMIZATION_FILE_PATH
           cd testdata/project-v4-multigroup
           go mod tidy
 

docs/book/src/cronjob-tutorial/testdata/project/cmd/main.go

@@ -136,6 +136,13 @@ func main() {
 		// TODO(user): If CertDir, CertName, and KeyName are not specified, controller-runtime will automatically
 		// generate self-signed certificates for the metrics server. While convenient for development and testing,
 		// this setup is not recommended for production.
+
+		// TODO(user): If cert-manager is enabled in config/default/kustomization.yaml,
+		// you can uncomment the following lines to use the certificate managed by cert-manager.
+		// metricsServerOptions.CertDir = "/tmp/k8s-metrics-server/metrics-certs"
+		// metricsServerOptions.CertName = "tls.crt"
+		// metricsServerOptions.KeyName = "tls.key"
+
 	}
 
 	mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), ctrl.Options{

docs/book/src/cronjob-tutorial/testdata/project/config/certmanager/certificate.yaml

@@ -33,3 +33,25 @@ spec:
     kind: Issuer
     name: selfsigned-issuer
   secretName: webhook-server-cert # this secret will not be prefixed, since it's not managed by kustomize
+---
+apiVersion: cert-manager.io/v1
+kind: Certificate
+metadata:
+  labels:
+    app.kubernetes.io/name: certificate
+    app.kubernetes.io/instance: metrics-certs
+    app.kubernetes.io/component: certificate
+    app.kubernetes.io/created-by: project
+    app.kubernetes.io/part-of: project
+    app.kubernetes.io/managed-by: kustomize
+  name: metrics-certs  # this name should match the one appeared in kustomizeconfig.yaml
+  namespace: system
+spec:
+  # SERVICE_NAME and SERVICE_NAMESPACE will be substituted by kustomize
+  dnsNames:
+  - controller-manager-metrics-service.system.svc
+  - controller-manager-metrics-service.system.svc.cluster.local
+  issuerRef:
+    kind: Issuer
+    name: selfsigned-issuer
+  secretName: metrics-server-cert # this secret will not be prefixed, since it's not managed by kustomize

docs/book/src/cronjob-tutorial/testdata/project/config/default/certmanager_metrics_manager_patch.yaml

@@ -0,0 +1,22 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: controller-manager
+  namespace: system
+  labels:
+    app.kubernetes.io/name: project
+    app.kubernetes.io/managed-by: kustomize
+spec:
+  template:
+    spec:
+      containers:
+      - name: manager
+        volumeMounts:
+        - mountPath: /tmp/k8s-metrics-server/metrics-certs
+          name: metrics-certs
+          readOnly: true
+      volumes:
+      - name: metrics-certs
+        secret:
+          defaultMode: 420
+          secretName: metrics-server-cert

docs/book/src/cronjob-tutorial/testdata/project/config/default/kustomization.yaml

@@ -33,14 +33,19 @@ resources:
 # be able to communicate with the Webhook Server.
 #- ../network-policy
 
-# Uncomment the patches line if you enable Metrics, and/or are using webhooks and cert-manager
+# Uncomment the patches line if you enable Metrics
 patches:
 # [METRICS] The following patch will enable the metrics endpoint using HTTPS and the port :8443.
 # More info: https://book.kubebuilder.io/reference/metrics
 - path: manager_metrics_patch.yaml
   target:
     kind: Deployment
 
+# Uncomment the patches line if you enable Metrics and CertManager
+# [METRICS WITH CERTMANGER] To enable metrics protected with certmanager, uncomment the following line.
+# This patch will protect the metrics with certmanager self-signed certs.
+- path: certmanager_metrics_manager_patch.yaml
+
 # [WEBHOOK] To enable webhook, uncomment all the sections with [WEBHOOK] prefix including the one in
 # crd/kustomization.yaml
 - path: manager_webhook_patch.yaml

docs/book/src/cronjob-tutorial/testdata/project/config/prometheus/kustomization.yaml

@@ -1,2 +1,11 @@
 resources:
 - monitor.yaml
+
+# [PROMETHEUS WITH CERTMANAGER] The following patch configures the ServiceMonitor in ../prometheus
+# to securely reference certificates created and managed by cert-manager.
+# Additionally, ensure that you uncomment the [METRICS WITH CERTMANAGER] patch under config/default/kustomization.yaml
+# to mount the "metrics-server-cert" secret in the Manager Deployment.
+patches:
+  - path: monitor_tls_patch.yaml
+    target:
+      kind: ServiceMonitor

docs/book/src/cronjob-tutorial/testdata/project/config/prometheus/monitor.yaml

@@ -16,14 +16,10 @@ spec:
       bearerTokenFile: /var/run/secrets/kubernetes.io/serviceaccount/token
       tlsConfig:
         # TODO(user): The option insecureSkipVerify: true is not recommended for production since it disables
-        # certificate verification. This poses a significant security risk by making the system vulnerable to
-        # man-in-the-middle attacks, where an attacker could intercept and manipulate the communication between
-        # Prometheus and the monitored services. This could lead to unauthorized access to sensitive metrics data,
-        # compromising the integrity and confidentiality of the information.
-        # Please use the following options for secure configurations:
-        # caFile: /etc/metrics-certs/ca.crt
-        # certFile: /etc/metrics-certs/tls.crt
-        # keyFile: /etc/metrics-certs/tls.key
+        # certificate verification, exposing the system to potential man-in-the-middle attacks.
+        # For production environments, it is recommended to use cert-manager for automatic TLS certificate management.
+        # To apply this configuration, enable cert-manager and use the patch located at config/prometheus/servicemonitor_tls_patch.yaml,
+        # which securely references the certificate from the 'metrics-server-cert' secret.
         insecureSkipVerify: true
   selector:
     matchLabels:

docs/book/src/cronjob-tutorial/testdata/project/config/prometheus/monitor_tls_patch.yaml

@@ -0,0 +1,22 @@
+# Patch for Prometheus ServiceMonitor to enable secure TLS configuration
+# using certificates managed by cert-manager
+apiVersion: monitoring.coreos.com/v1
+kind: ServiceMonitor
+metadata:
+  name: controller-manager-metrics-monitor
+  namespace: system
+spec:
+  endpoints:
+    - tlsConfig:
+        insecureSkipVerify: false
+        ca:
+          secret:
+            name: metrics-server-cert
+            key: ca.crt
+        cert:
+          secret:
+            name: metrics-server-cert
+            key: tls.crt
+        keySecret:
+          name: metrics-server-cert
+          key: tls.key

docs/book/src/getting-started/testdata/project/cmd/main.go

@@ -116,6 +116,13 @@ func main() {
 		// TODO(user): If CertDir, CertName, and KeyName are not specified, controller-runtime will automatically
 		// generate self-signed certificates for the metrics server. While convenient for development and testing,
 		// this setup is not recommended for production.
+
+		// TODO(user): If cert-manager is enabled in config/default/kustomization.yaml,
+		// you can uncomment the following lines to use the certificate managed by cert-manager.
+		// metricsServerOptions.CertDir = "/tmp/k8s-metrics-server/metrics-certs"
+		// metricsServerOptions.CertName = "tls.crt"
+		// metricsServerOptions.KeyName = "tls.key"
+
 	}
 
 	mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), ctrl.Options{

docs/book/src/getting-started/testdata/project/config/default/certmanager_metrics_manager_patch.yaml

@@ -0,0 +1,22 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: controller-manager
+  namespace: system
+  labels:
+    app.kubernetes.io/name: project
+    app.kubernetes.io/managed-by: kustomize
+spec:
+  template:
+    spec:
+      containers:
+      - name: manager
+        volumeMounts:
+        - mountPath: /tmp/k8s-metrics-server/metrics-certs
+          name: metrics-certs
+          readOnly: true
+      volumes:
+      - name: metrics-certs
+        secret:
+          defaultMode: 420
+          secretName: metrics-server-cert