[mqtt-exporter] New chart (#33)

* [mqtt-exporter] New chart

* Don't enable Metrics for testing

* Fix linting issues

charts/mqtt-exporter/templates/NOTES.txt

@@ -0,0 +1 @@
+{{- include "common.notes.defaultNotes" . -}}

charts/mqtt-exporter/templates/common.yaml

@@ -0,0 +1 @@
+{{ include "common.all" . }}

charts/mqtt-exporter/templates/prometheusrules.yaml

@@ -0,0 +1,27 @@
+{{- if and .Values.metrics.enabled .Values.metrics.prometheusRule.enabled }}
+apiVersion: monitoring.coreos.com/v1
+kind: PrometheusRule
+metadata:
+  name: {{ include "common.names.fullname" . }}
+  labels:
+    {{- include "common.labels" . | nindent 4 }}
+    {{- with .Values.metrics.prometheusRule.labels }}
+    {{- toYaml . | nindent 4 }}
+    {{- end }}
+spec:
+  groups:
+    - name: {{ include "common.names.fullname" . }}
+      rules:
+        - alert: MQTTExporterAbsent
+          annotations:
+            description: MQTT Exporter has disappeared from Prometheus service discovery.
+            summary: MQTT Exporter is down.
+          expr: |
+            absent(up{job=~".*{{ include "common.names.fullname" . }}.*"} == 1)
+          for: 5m
+          labels:
+            severity: critical
+        {{- with .Values.metrics.prometheusRule.rules }}
+        {{- toYaml . | nindent 8 }}
+        {{- end }}
+{{- end }}

charts/mqtt-exporter/templates/servicemonitor.yaml

@@ -0,0 +1,24 @@
+{{- if .Values.metrics.enabled }}
+apiVersion: monitoring.coreos.com/v1
+kind: ServiceMonitor
+metadata:
+  name: {{ include "common.names.fullname" . }}
+  labels:
+    {{- include "common.labels" . | nindent 4 }}
+    {{- with .Values.metrics.serviceMonitor.labels }}
+    {{- toYaml . | nindent 4 }}
+    {{- end }}
+spec:
+  selector:
+    matchLabels:
+      {{- include "common.labels.selectorLabels" . | nindent 6 }}
+  endpoints:
+    - port: metrics
+      {{- with .Values.metrics.serviceMonitor.interval }}
+      interval: {{ . }}
+      {{- end }}
+      {{- with .Values.metrics.serviceMonitor.scrapeTimeout }}
+      scrapeTimeout: {{ . }}
+      {{- end }}
+      path: /metrics
+{{- end }}