feat: Define Prometheus port in the pod spec (#5213)

* WIP

* portSpec

* Done

* Docs

* Fix: env

helm/README.md

@@ -50,6 +50,9 @@ coder:
     - name: CODER_AUTO_IMPORT_TEMPLATES
       value: "kubernetes"
 
+    # This env enables the Prometheus metrics endpoint.
+    - name: CODER_PROMETHEUS_ADDRESS
+      value: "0.0.0.0:2112"
   tls:
     secretNames:
       - my-tls-secret-name

helm/templates/coder.yaml

@@ -77,10 +77,23 @@ spec:
             {{- with .Values.coder.env -}}
             {{ toYaml . | nindent 12 }}
             {{- end }}
+            {{- range .Values.coder.env }}
+            {{- if eq .name "CODER_PROMETHEUS_ADDRESS" }}
+            - name: CODER_PROMETHEUS_ENABLE
+              value: "true"
+            {{- end }}
+            {{- end }}
           ports:
             - name: {{ include "coder.portName" . | quote }}
               containerPort: {{ include "coder.port" . }}
               protocol: TCP
+            {{- range .Values.coder.env }}
+            {{- if eq .name "CODER_PROMETHEUS_ADDRESS" }}
+            - name: "prometheus-http"
+              containerPort: {{ (splitList ":" .value) | last }}
+              protocol: TCP
+            {{- end }}
+            {{- end }}
           readinessProbe:
             httpGet:
               path: /api/v2/buildinfo

helm/values.yaml

@@ -49,6 +49,7 @@ coder:
   # - CODER_TLS_ENABLE: set if tls.secretName is not empty.
   # - CODER_TLS_CERT_FILE: set if tls.secretName is not empty.
   # - CODER_TLS_KEY_FILE: set if tls.secretName is not empty.
+  # - CODER_PROMETHEUS_ENABLE: set if CODER_PROMETHEUS_ADDRESS is not empty.
   env: []
 
   # coder.tls -- The TLS configuration for Coder.