Add optional ServiceMonitor object to Helm chart

This adds the ability to create a ServiceMonitor instance to configure
Prometheus to monitor reloader for metrics. ServiceMonitor is a CRD that
comes with the prometheus-operator project.

deployments/kubernetes/chart/reloader/templates/servicemonitor.yaml

@@ -0,0 +1,31 @@
+{{- if and ( .Capabilities.APIVersions.Has "monitoring.coreos.com/v1" ) ( .Values.reloader.serviceMonitor.enabled ) }}
+apiVersion: monitoring.coreos.com/v1
+kind: ServiceMonitor
+metadata:
+  labels:
+{{ include "reloader-labels.chart" . | indent 4 }}
+{{- if .Values.reloader.serviceMonitor.labels }}
+{{ toYaml .Values.reloader.serviceMonitor.labels | indent 4}}
+{{- end }}
+  name: {{ template "reloader-fullname" . }}
+{{- if .Values.reloader.serviceMonitor.namespace }}
+  namespace: {{ .Values.reloader.serviceMonitor.namespace }}
+{{- end }}
+spec:
+  endpoints:
+  - targetPort: http
+    path: "/metrics"
+{{- if .Values.reloader.serviceMonitor.interval }}
+    interval: {{ .Values.reloader.serviceMonitor.interval }}
+{{- end }}
+{{- if .Values.reloader.serviceMonitor.timeout }}
+    scrapeTimeout: {{ .Values.reloader.serviceMonitor.timeout }}
+{{- end }}
+  jobLabel: {{ template "reloader-fullname" . }}
+  namespaceSelector:
+    matchNames:
+    - {{ .Release.Namespace }}
+  selector:
+    matchLabels:
+      {{ include "reloader-labels.chart" . | nindent 6 }}
+{{- end }}

deployments/kubernetes/chart/reloader/values.yaml

@@ -104,3 +104,14 @@ reloader:
   #     configmap: "my.company.com/configmap"
   #     secret: "my.company.com/secret"
   custom_annotations: {}
+  serviceMonitor:
+    # enabling this requires service to be enabled as well, or no endpoints will be found
+    enabled: false
+    # Set the namespace the ServiceMonitor should be deployed
+    # namespace: monitoring
+    # Set how frequently Prometheus should scrape
+    # interval: 30s
+    # Set labels for the ServiceMonitor, use this to define your scrape label for Prometheus Operator
+    # labels:
+    # Set timeout for scrape
+    # timeout: 10s