Add support for metrics and pprof (#100)

Adds support for toggling support for `pprof` and metrics:

```yaml
gitea:
  pprofEnabled: true

  metrics:
    enabled: true
    serviceMonitor:
      enabled: true
```

Co-authored-by: josef <josef.nilsen@outlook.com>
Reviewed-on: https://gitea.com/gitea/helm-chart/pulls/100
Reviewed-by: luhahn <luhahn@noreply.gitea.io>
Reviewed-by: techknowlogick <techknowlogick@gitea.io>
Co-authored-by: JosefWN <josefwn@noreply.gitea.io>
Co-committed-by: JosefWN <josefwn@noreply.gitea.io>

README.md

@@ -95,6 +95,16 @@ ROOT_URL = http://git.example.com
 SSH_DOMAIN = git.example.com
 SSH_LISTEN_PORT = 22
 SSH_PORT = 22
+ENABLE_PPROF = false
+```
+
+#### Metrics defaults
+
+The Prometheus `/metrics` endpoint is disabled by default.
+
+```ini
+[metrics]
+ENABLED = false
 ```
 
 ### External Database
@@ -278,6 +288,24 @@ kebab-case:
       username-attribute: CN
 ```
 
+### Metrics and profiling
+
+A Prometheus `/metrics` endpoint on the `HTTP_PORT` and `pprof` profiling endpoints on port 6060 can be enabled under `gitea`. Beware that the metrics endpoint is exposed via the ingress, manage access using ingress annotations for example.
+
+To deploy the `ServiceMonitor`, you first need to ensure that you have deployed `prometheus-operator` and its CRDs: https://github.com/prometheus-operator/prometheus-operator#customresourcedefinitions.
+
+```yaml
+gitea:
+  metrics:
+    enabled: true
+    serviceMonitor:
+      enabled: true
+
+  config:
+    server:
+      PPROF_ENABLED: true
+```
+
 ### Pod Annotations
 
 Annotations can be added to the Gitea pod.

templates/gitea/config.yaml

@@ -15,6 +15,10 @@ stringData:
     {{- $_ := set .Values.gitea.config "server" dict -}}
     {{- end -}}
 
+    {{- if not (hasKey .Values.gitea.config "metrics") -}}
+    {{- $_ := set .Values.gitea.config "metrics" dict -}}
+    {{- end -}}
+
     {{- if not (hasKey .Values.gitea.config "database") -}}
     {{- $_ := set .Values.gitea.config "database" dict -}}
     {{- end -}}
@@ -65,6 +69,14 @@ stringData:
     {{- if not (hasKey .Values.gitea.config.server "APP_DATA_PATH") -}}
     {{- $_ := set .Values.gitea.config.server "APP_DATA_PATH" "/data" -}}
     {{- end -}}
+    {{- if not (hasKey .Values.gitea.config.server "PPROF_ENABLED") -}}
+    {{- $_ := set .Values.gitea.config.server "PPROF_ENABLED" false -}}
+    {{- end -}}
+
+    {{- /* metrics default settings */ -}}
+    {{- if not (hasKey .Values.gitea.config.metrics "ENABLED") -}}
+    {{- $_ := set .Values.gitea.config.metrics "ENABLED" .Values.gitea.metrics.enabled -}}
+    {{- end -}}
 
     {{- /* database default settings */ -}}
     {{- if .Values.gitea.database.builtIn.postgresql.enabled -}}

templates/gitea/servicemonitor.yaml

@@ -0,0 +1,14 @@
+{{- if .Values.gitea.metrics.serviceMonitor.enabled -}}
+apiVersion: monitoring.coreos.com/v1
+kind: ServiceMonitor
+metadata:
+  name: {{ include "gitea.fullname" . }}
+  labels:
+    {{- include "gitea.labels" . | nindent 4 }}
+spec:
+  selector:
+    matchLabels:
+      {{- include "gitea.selectorLabels" . | nindent 6 }}
+  endpoints:
+  - port: http
+{{- end -}}

templates/gitea/statefulset.yaml

@@ -66,6 +66,10 @@ spec:
               containerPort: {{ .Values.gitea.config.server.SSH_LISTEN_PORT }}
             - name: http
               containerPort: {{ .Values.gitea.config.server.HTTP_PORT }}
+            {{- if .Values.gitea.config.server.PPROF_ENABLED }}
+            - name: profiler
+              containerPort: 6060
+            {{- end }}
           livenessProbe:
             tcpSocket:
               port: http

values.yaml

@@ -105,6 +105,11 @@ gitea:
     password: r8sA8CPHD9!bt6d
     email: "gitea@local.domain"
 
+  metrics:
+    enabled: false
+    serviceMonitor:
+      enabled: false
+
   ldap:
     enabled: false
     #name: