Add support for securing the operator metrics endpoint with RBAC and TLS

cmd/manager/main.go

@@ -286,7 +286,12 @@ func Command() *cobra.Command {
 	cmd.Flags().Int(
 		operator.MetricsPortFlag,
 		DefaultMetricPort,
-		"Port to use for exposing metrics in the Prometheus format (set 0 to disable)",
+		"Port to use for exposing metrics in the Prometheus format. (set 0 to disable)",
+	)
+	cmd.Flags().String(
+		operator.MetricsHostFlag,
+		"0.0.0.0",
+		fmt.Sprintf("The host to which the operator should bind to serve metrics in the Prometheus format. Will be combined with %s.", operator.MetricsPortFlag),
 	)
 	cmd.Flags().StringSlice(
 		operator.NamespacesFlag,
@@ -577,11 +582,12 @@ func startOperator(ctx context.Context) error {
 
 	// only expose prometheus metrics if provided a non-zero port
 	metricsPort := viper.GetInt(operator.MetricsPortFlag)
+	metricsHost := viper.GetString(operator.MetricsHostFlag)
 	if metricsPort != 0 {
-		log.Info("Exposing Prometheus metrics on /metrics", "port", metricsPort)
+		log.Info("Exposing Prometheus metrics on /metrics", "bindAddress", fmt.Sprintf("%s:%d", metricsHost, metricsPort))
 	}
 	opts.Metrics = metricsserver.Options{
-		BindAddress: fmt.Sprintf(":%d", metricsPort), // 0 to disable
+		BindAddress: fmt.Sprintf("%s:%d", metricsHost, metricsPort), // 0 to disable
 	}
 
 	webhookPort := viper.GetInt(operator.WebhookPortFlag)

deploy/eck-operator/templates/_helpers.tpl

@@ -114,6 +114,19 @@ elastic-webhook-server
 {{- end -}}
 {{- end -}}
 
+{{/*
+Determine the metrics port
+*/}}
+{{- define "eck-operator.metrics.port" -}}
+{{- if .Values.config.metrics.port -}}
+{{- .Values.config.metrics.port -}}
+{{- else if .Values.config.metricsPort -}}
+{{- .Values.config.metricsPort -}}
+{{- else -}}
+0
+{{- end -}}
+{{- end -}}
+
 {{/*
 RBAC permissions
 NOTE - any changes made to RBAC permissions below require

deploy/eck-operator/templates/auth-proxy-service.yaml

@@ -0,0 +1,22 @@
+{{- if .Values.config.metrics.secureMode.enabled }}
+{{- $metricsPort := int (include "eck-operator.metrics.port" .)}}
+apiVersion: v1
+kind: Service
+metadata:
+  labels:
+    app.kubernetes.io/name: {{ include "eck-operator.name" . }}-metrics-service
+    app.kubernetes.io/instance: {{ .Release.Name }}
+    app.kubernetes.io/version: {{ .Chart.AppVersion | quote }}
+    helm.sh/chart: {{ include "eck-operator.chart" . }}
+    app.kubernetes.io/managed-by: {{ .Release.Service }}
+  name: "{{ include "eck-operator.fullname" . }}-metrics"
+  namespace: {{ .Release.Namespace }}
+spec:
+  ports:
+  - name: https
+    port: {{ $metricsPort }}
+    protocol: TCP
+    targetPort: metrics
+  selector:
+    {{- include "eck-operator.selectorLabels" . | nindent 4 }}
+{{- end }}

deploy/eck-operator/templates/cluster-roles.yaml

@@ -1,3 +1,6 @@
+{{- if and (not .Values.createClusterScopedResources) (.Values.config.metrics.secureMode.enabled) -}}
+{{ fail "createClusterScopedResources is required to enable secure metrics" }}
+{{- end }}
 {{- if .Values.createClusterScopedResources -}}
 ---
 apiVersion: rbac.authorization.k8s.io/v1
@@ -93,4 +96,26 @@ rules:
   - apiGroups: ["logstash.k8s.elastic.co"]
     resources: ["logstashes"]
     verbs: ["create", "delete", "deletecollection", "patch", "update"]
+{{- if and .Values.config.metrics.secureMode.enabled }}
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRole
+metadata:
+  labels:
+    {{- include "eck-operator.labels" . | nindent 4 }}
+  name: "{{ include "eck-operator.fullname" . }}-proxy-role"
+rules:
+- apiGroups:
+  - authentication.k8s.io
+  resources:
+  - tokenreviews
+  verbs:
+  - create
+- apiGroups:
+  - authorization.k8s.io
+  resources:
+  - subjectaccessreviews
+  verbs:
+  - create
+{{- end }}
 {{- end -}}

deploy/eck-operator/templates/configmap.yaml

@@ -8,8 +8,16 @@ metadata:
     {{- include "eck-operator.labels" . | nindent 4 }}
 data:
   eck.yaml: |-
+    {{- $metricsPort := int (include "eck-operator.metrics.port" .)}}
     log-verbosity: {{ int .Values.config.logVerbosity }}
-    metrics-port: {{ int .Values.config.metricsPort }}
+    {{- if and .Values.config.metrics.secureMode.enabled (eq $metricsPort 0) }}
+    {{- fail "metricsPort must be greater than 0 when enableSecureMetrics is true" }}
+    {{- end }}
+    {{- if .Values.config.metrics.secureMode.enabled }}
+    metrics-port: {{ add $metricsPort 1 }}
+    {{- else }}
+    metrics-port: {{ $metricsPort }}
+    {{- end }}
     container-registry: {{ .Values.config.containerRegistry }}
     {{- with .Values.config.containerSuffix }}
     container-suffix: {{ . }}

deploy/eck-operator/templates/operator-network-policy.yaml

@@ -1,6 +1,6 @@
 {{- if .Values.softMultiTenancy.enabled -}}
 {{- $kubeAPIServerIP := (required "kubeAPIServerIP is required" .Values.kubeAPIServerIP) -}}
-{{- $metricsPort := int .Values.config.metricsPort -}}
+{{- $metricsPort := int (include "eck-operator.metrics.port" .)}}
 ---
 apiVersion: networking.k8s.io/v1
 kind: NetworkPolicy

deploy/eck-operator/templates/podMonitor.yaml

@@ -1,10 +1,13 @@
-{{- $metricsPort := int .Values.config.metricsPort -}}
+{{- $metricsPort := int (include "eck-operator.metrics.port" .)}}
 {{- if and .Values.podMonitor.enabled (gt $metricsPort 0) }}
+{{- if and .Values.podMonitor.enabled .Values.config.metrics.secureMode.enabled }}
+{{- fail "podMonitor and secureMode are mutually exclusive" }}
+{{- end }}
 apiVersion: monitoring.coreos.com/v1
 kind: PodMonitor
 metadata:
   name: {{ include "eck-operator.fullname" . }}
-  namespace: {{ ternary .Values.podMonitor.namespace .Release.Namespace (not (empty .Values.podMonitor.namespace)) }}
+  namespace: {{ ternary .Values.podMonitor.namespace .Release.Namespace (not (and (.Values.podMonitor) (empty .Values.podMonitor.namespace))) }}
   labels: {{- include "eck-operator.labels" . | nindent 4 }}
   {{- with .Values.podMonitor.labels }}
     {{- toYaml . | nindent 4 }}
@@ -33,4 +36,4 @@ spec:
       - {{ .Release.Namespace }}
   selector:
     matchLabels: {{- include "eck-operator.selectorLabels" . | nindent 6 }}
-{{- end }}
+{{- end }}

deploy/eck-operator/templates/role-bindings.yaml

@@ -1,6 +1,7 @@
 {{- $operatorNSIsManaged := has .Release.Namespace .Values.managedNamespaces -}}
 {{- $fullName := include "eck-operator.fullname" . -}}
 {{- $svcAccount := include "eck-operator.serviceAccountName" . }}
+{{- $enableSecureMetrics := .Values.config.metrics.secureMode.enabled -}}
 
 {{- if not .Values.createClusterScopedResources }}
 {{- range .Values.managedNamespaces }}
@@ -77,4 +78,21 @@ subjects:
 - kind: ServiceAccount
   name: {{ $svcAccount }}
   namespace: {{ $.Release.Namespace }}
+{{- if $enableSecureMetrics }}
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRoleBinding
+metadata:
+  labels:
+    {{- include "eck-operator.labels" $ | nindent 4 }}
+  name: "{{ include "eck-operator.fullname" . }}-proxy-rolebinding"
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: ClusterRole
+  name: "{{ include "eck-operator.fullname" . }}-proxy-role"
+subjects:
+- kind: ServiceAccount
+  name: {{ $svcAccount }}
+  namespace: {{ $.Release.Namespace }}
+{{- end }}
 {{- end }}

deploy/eck-operator/templates/serviceMonitor.yaml

@@ -0,0 +1,31 @@
+{{- if and .Values.config.metrics.secureMode.enabled }}
+apiVersion: monitoring.coreos.com/v1
+kind: ServiceMonitor
+metadata:
+  name: {{ include "eck-operator.fullname" . }}
+  namespace: {{ ternary .Values.serviceMonitor.namespace .Release.Namespace (not (and (.Values.serviceMonitor) (empty .Values.serviceMonitor.namespace))) }}
+  labels: {{- include "eck-operator.labels" . | nindent 4 }}
+spec:
+  namespaceSelector:
+    matchNames:
+      - {{ .Release.Namespace }}
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: {{ include "eck-operator.name" . }}-metrics-service
+      app.kubernetes.io/instance: {{ .Release.Name }}
+  endpoints:
+  - port: https
+    path: /metrics
+    scheme: https
+    interval: 30s
+    tlsConfig:
+      insecureSkipVerify: {{ .Values.config.metrics.secureMode.tls.insecureSkipVerify | default false }}
+      {{- if (not .Values.config.metrics.secureMode.tls.insecureSkipVerify) }}
+      {{- with .Values.config.metrics.secureMode.tls.caSecret }}
+      {{- $leading_path := trimSuffix "/" .Values.config.metrics.secureMode.tls.caMountDirectory }}
+      caFile: "{{ $leading_path }}/{{ . }}/ca.crt"
+      {{- end }}
+      serverName: "{{ include "eck-operator.fullname" . }}-metrics.{{ .Release.Namespace }}.svc"
+      {{- end }}
+    bearerTokenFile: /var/run/secrets/kubernetes.io/serviceaccount/token
+{{- end }}

deploy/eck-operator/templates/statefulset.yaml

@@ -1,5 +1,5 @@
-{{- $metricsPort := int .Values.config.metricsPort -}}
 ---
+{{- $metricsPort := int (include "eck-operator.metrics.port" .)}}
 apiVersion: apps/v1
 kind: StatefulSet
 metadata:
@@ -79,10 +79,10 @@ spec:
           resources:
             {{- toYaml . | nindent 12 }}
           {{- end }}
-          {{- if or (gt $metricsPort 0) .Values.webhook.enabled }}
+          {{- if or .Values.webhook.enabled (gt $metricsPort 0) }}
           ports:
-            {{- if (gt $metricsPort 0) }}
-            - containerPort: {{ .Values.config.metricsPort }}
+            {{- if and (gt $metricsPort 0) (not .Values.config.metrics.secureMode.enabled) }}
+            - containerPort: {{ $metricsPort }}
               name: metrics
               protocol: TCP
             {{- end }}
@@ -104,6 +104,41 @@ spec:
             {{- with .Values.volumeMounts }}
               {{- toYaml . | nindent 12 }}
             {{- end }}
+        {{- if .Values.config.metrics.secureMode.enabled }}
+        - name: kube-rbac-proxy
+          securityContext:
+            allowPrivilegeEscalation: false
+            capabilities:
+              drop:
+                - "ALL"
+          image: gcr.io/kubebuilder/kube-rbac-proxy:v0.15.0
+          args:
+          - "--secure-listen-address=0.0.0.0:{{ $metricsPort }}"
+          - "--upstream=http://127.0.0.1:{{ add $metricsPort 1 }}/"
+          - "--logtostderr=true"
+          - "--v=0"
+          {{- if .Values.config.metrics.secureMode.tls.certificateSecret }}
+          - "--tls-cert-file=/tls/tls.crt"
+          - "--tls-private-key-file=/tls/tls.key"
+          {{- end }}
+          {{- if .Values.config.metrics.secureMode.tls.certificateSecret }}
+          volumeMounts:
+          - mountPath: "/tls"
+            name: tls-certificate
+            readOnly: true
+          {{- end }}
+          ports:
+          - containerPort: {{ $metricsPort }}
+            protocol: TCP
+            name: metrics
+          resources:
+            limits:
+              cpu: 500m
+              memory: 128Mi
+            requests:
+              cpu: 5m
+              memory: 64Mi
+        {{- end }}
       volumes:
         - name: conf
           configMap:
@@ -114,6 +149,12 @@ spec:
             defaultMode: 420
             secretName: {{ include "eck-operator.webhookSecretName" . }}
         {{- end }}
+        {{- if .Values.config.metrics.secureMode.tls.certificateSecret }}
+        - name: tls-certificate
+          secret:
+            defaultMode: 420
+            secretName: {{ .Values.config.metrics.secureMode.tls.certificateSecret  }}
+        {{- end }}
         {{- with .Values.volumes }}
           {{- toYaml . | nindent 8 }}
         {{- end }}

deploy/eck-operator/values.yaml

@@ -159,8 +159,67 @@ config:
   #  number greater than 0: Errors, warnings, information, and debug details.
   logVerbosity: "0"
 
-  # metricsPort defines the port to expose operator metrics. Set to 0 to disable metrics reporting.
-  metricsPort: "0"
+  # (Deprecated: use metrics.port: will be removed in v2.14.0) metricsPort defines the port to expose operator metrics. Set to 0 to disable metrics reporting.
+  metricsPort: 0
+
+  metrics:
+    # port defines the port to expose operator metrics. Set to 0 to disable metrics reporting.
+    port: "0"
+    # secureMode contains the options for enabling and configuring RBAC and TLS/HTTPs for the metrics endpoint.
+    secureMode:
+      # secureMode.enabled specifies whether to enable RBAC and TLS/HTTPs for the metrics endpoint. (Will be enabled by default in v2.14.0)
+      # * This option requires using a ServiceMonitor to scrape the metrics and as such is mutually exclusive with the podMonitor.enabled option.
+      # * This option also requires using cluster scoped resources (ClusterRole, ClusterRoleBinding) to
+      #   grant access to the /metrics endpoint. (createClusterScopedResources: true is required)
+      #
+      # This option requires the following settings within Prometheus to function:
+      # 1. RBAC settings for the Prometheus instance to access the metrics endpoint.
+      #
+      # - nonResourceURLs:
+      #   - /metrics
+      #   verbs:
+      #   - get
+      #
+      # 2. If using the Prometheus Operator and your Prometheus instance is not in the same namespace as the operator you will need
+      #    the Prometheus Operator configured with the following Helm values:
+      #
+      #   prometheus:
+      #     prometheusSpec:
+      #       serviceMonitorNamespaceSelector: {}
+      #       serviceMonitorSelectorNilUsesHelmValues: false
+      enabled: false
+      tls:
+        # certificateSecret is the name of the tls secret containing the custom TLS certificate and key for the secure metrics endpoint.
+        #
+        # * This is an optional setting and is only required if you are using a custom TLS certificate. A self-signed certificate will be generated by default.
+        # * TLS secret key must be named tls.crt.
+        # * TLS key's secret key must be named tls.key.
+        # * It is assumed to be in the same namespace as the ServiceMonitor.
+        #
+        # example: kubectl create secret tls eck-metrics-tls-certificate -n elastic-system \
+        #            --cert=/path/to/tls.crt --key=/path/to/tls.key
+        certificateSecret: ""
+        # caSecret is the name of the secret containing the custom CA certificate used to generate the custom TLS certificate for the secure metrics endpoint.
+        #
+        # * This *must* be the name of the secret containing the CA certificate used to sign the custom TLS certificate.
+        # * This secret *must* be in the same namespace as the Prometheus instance that will scrape the metrics.
+        # * If using the Prometheus operator this secret must be within the `spec.secrets` field of the `Prometheus` custom resource such that it is mounted into the Prometheus pod at `caMountDirectory`, which defaults to /etc/prometheus/secrets/{secret-name}.
+        # * This is an optional setting and is only required if you are using a custom TLS certificate.
+        # * Key must be named ca.crt.
+        #
+        # example: kubectl create secret generic eck-metrics-tls-ca -n monitoring \
+        #            --from-file=ca.crt=/path/to/ca.pem
+        caSecret: ""
+        # caMountDirectory is the directory at which the CA certificate is mounted within the Prometheus pod.
+        #
+        # * You should only need to adjust this if you are *not* using the Prometheus operator.
+        caMountDirectory: "/etc/prometheus/secrets/"
+        # insecureSkipVerify specifies whether to skip verification of the TLS certificate for the secure metrics endpoint.
+        #
+        # * If this setting is set to false, then the following settings are required:
+        #   - certificateSecret
+        #   - caSecret
+        insecureSkipVerify: true
 
   # containerRegistry to use for pulling Elasticsearch and other application container images.
   containerRegistry: docker.elastic.co
@@ -258,6 +317,15 @@ podMonitor:
   podMetricsEndpointConfig: {}
   # honorTimestamps: true
 
+# Prometheus ServiceMonitor configuration
+# Only used when config.enableSecureMetrics is true
+# Reference: https://github.com/prometheus-operator/prometheus-operator/blob/master/Documentation/api.md#servicemonitor
+serviceMonitor: {}
+
+  # namespace determines in which namespace the servicedMonitor will be deployed.
+  # If not set the servicedMonitor will be created in the namespace where the Helm release is installed into
+  # namespace: monitoring
+
 # Globals meant for internal use only
 global:
   # manifestGen specifies whether the chart is running under manifest generator.