Limit the Prometheus role to two namespaces

Unless clusterRole is specified, the Prometheus role will be
restricted to scraping from only a single namespace.

This fixes issue: #717 where I user complained that they did
not want to create a ClusterRole in their cluster.

It has been tested with k3d and K8s 1.19 with and without the
--set clusterRole=true flag passed into the faas-netes helm
chart.

The second Role and RoleBinding needed a different name to the
ones in the primary namespace in order for the RBAC error to
go away in Prometheus.

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <[email protected]>

Author: alexellis

chart/openfaas/templates/prometheus-rbac.yaml

@@ -1,5 +1,6 @@
 {{- $functionNs := default .Release.Namespace .Values.functionNamespace }}
 {{- if .Values.prometheus.create }}
+
 ---
 apiVersion: v1
 kind: ServiceAccount
@@ -13,6 +14,9 @@ metadata:
     heritage: {{ .Release.Service }}
     release: {{ .Release.Name }}
 ---
+
+{{- if .Values.clusterRole }}
+
 apiVersion: rbac.authorization.k8s.io/v1
 kind: ClusterRole
 metadata:
@@ -72,4 +76,87 @@ subjects:
   name: {{ .Release.Name }}-prometheus
   namespace: {{ .Release.Namespace | quote }}
 {{- end }}
+
+{{- else -}}
+
+apiVersion: rbac.authorization.k8s.io/v1
+kind: Role
+metadata:
+  name: {{ .Release.Name }}-prometheus
+  labels:
+    app: {{ template "openfaas.name" . }}
+    chart: {{ .Chart.Name }}-{{ .Chart.Version }}
+    component: prometheus
+    heritage: {{ .Release.Service }}
+    release: {{ .Release.Name }}
+rules:
+- apiGroups: [""]
+  resources:
+    - services
+    - endpoints
+    - pods
+  verbs: ["get", "list", "watch"]
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: RoleBinding
+metadata:
+  name: {{ .Release.Name }}-prometheus
+  namespace: {{ .Release.Namespace | quote }}
+  labels:
+    app: {{ template "openfaas.name" . }}
+    chart: {{ .Chart.Name }}-{{ .Chart.Version }}
+    component: prometheus
+    heritage: {{ .Release.Service }}
+    release: {{ .Release.Name }}
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: Role
+  name: {{ .Release.Name }}-prometheus
+subjects:
+- kind: ServiceAccount
+  name: {{ .Release.Name }}-prometheus
+  namespace: {{ .Release.Namespace | quote }}
+{{- if ne $functionNs (.Release.Namespace | toString) }}
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: Role
+metadata:
+  name: {{ .Release.Name }}-prometheus-fn
+  namespace: {{ $functionNs | quote }}
+  labels:
+    app: {{ template "openfaas.name" . }}
+    chart: {{ .Chart.Name }}-{{ .Chart.Version }}
+    component: prometheus
+    heritage: {{ .Release.Service }}
+    release: {{ .Release.Name }}
+rules:
+- apiGroups: [""]
+  resources:
+    - services
+    - endpoints
+    - pods
+  verbs: ["get", "list", "watch"]
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: RoleBinding
+metadata:
+  name: {{ .Release.Name }}-prometheus-fn
+  namespace: {{ $functionNs | quote }}
+  labels:
+    app: {{ template "openfaas.name" . }}
+    chart: {{ .Chart.Name }}-{{ .Chart.Version }}
+    component: prometheus
+    heritage: {{ .Release.Service }}
+    release: {{ .Release.Name }}
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: Role
+  name: {{ .Release.Name }}-prometheus-fn
+subjects:
+- kind: ServiceAccount
+  name: {{ .Release.Name }}-prometheus
+  namespace: {{ .Release.Namespace | quote }}
+{{- end }}
+
 {{- end }}
+{{- end }}