[helm] Enable metrics reporting on helm charts

helm/README.md

@@ -22,7 +22,7 @@ This chart deploys an Apache Fluss cluster on Kubernetes, following Helm best pr
 It requires a Zookeeper ensemble to be running in the same Kubernetes cluster. In future releases, we may add support for an embedded Zookeeper cluster.
 
 
-## Development environment 
+## Development environment
 
 | component                                                                      | version |
 | ------------------------------------------------------------------------------ | ------- |
@@ -33,7 +33,7 @@ It requires a Zookeeper ensemble to be running in the same Kubernetes cluster. I
 | [Apache Fluss](https://fluss.apache.org/docs/)                                 | v0.10.0-incubating  |
 
 
-## Image requirements 
+## Image requirements
 
 A container image for Fluss is available on DockerHub as `fluss/fluss`. You can use it directly or build your own from this repo. To use your own image you need to build the project with [Maven](https://fluss.apache.org/community/dev/building/) and build it with Docker.
 
@@ -93,6 +93,81 @@ Important Fluss options surfaced by the chart:
 - internal.listener.name: Which listener is used for internal communication (defaults to INTERNAL).
 - tablet-server.id: Required to be unique per TabletServer. The chart auto‑derives this from the StatefulSet pod ordinal at runtime.
 
+### Metrics and Prometheus Scraping
+
+The chart can enable Fluss metrics reporters and create dedicated metrics services for `coordinator` and `tablet` components.
+
+Example:
+
+```bash
+helm install fluss ./fluss-helm \
+  --set metrics.enabled=true
+```
+
+When enabled, the chart will:
+
+- configure `metrics.reporters` from reporter names in values
+- configure `metrics.reporter.<name>.<option>` entries from values
+
+Values:
+
+| Key | Description |
+| --- | --- |
+| `metrics.enabled` | Enables metrics reporting and endpoint exposure. |
+| `metrics.reporters` | Map of Fluss metric reporters and their options. |
+| `metrics.reporters.jmx.port` | JMX reporter port range (e.g. `9250-9260`). |
+| `metrics.reporters.prometheus.port` | Prometheus reporter port (default `9249`). |
+| `metrics.reporters.prometheus.service.portName` | Named port exposed by metrics services (default `metrics`). |
+| `metrics.reporters.prometheus.service.labels` | Optional labels on metrics services (useful for [ServiceMonitor](https://prometheus-operator.dev/docs/api-reference/api/#monitoring.coreos.com/v1.ServiceMonitor) selectors). |
+| `metrics.reporters.prometheus.service.annotations` | Optional annotations on metrics services (useful for annotation-based scraping). |
+
+#### Prometheus Annotation Based Scraping
+
+The values below enable annotation based scraping:
+
+```yaml
+metrics:
+  enabled: true
+  reporters:
+    prometheus:
+      port: 9249
+      service:
+        annotations:
+          prometheus.io/scrape: "true"
+          prometheus.io/path: "/metrics"
+          prometheus.io/port: "9249"
+```
+
+#### Prometheus ServiceMonitor Based Scraping
+
+When using the [Prometheus Operator](https://prometheus-operator.dev/), use the values below to add labels to the metrics services and then create a `ServiceMonitor` that selects them:
+
+```yaml
+metrics:
+  enabled: true
+  reporters:
+    prometheus:
+      port: 9249
+      service:
+        portName: metrics
+        labels:
+          monitoring: enabled
+```
+
+Apply the following to create a `ServiceMonitor` resource that matches the label:
+
+```yaml
+apiVersion: monitoring.coreos.com/v1
+kind: ServiceMonitor
+metadata:
+  name: fluss-metrics
+spec:
+  selector:
+    matchLabels:
+      monitoring: enabled
+  endpoints:
+    - port: metrics
+```
 
 ### Zookeeper and storage
 - zookeeper.address must point to a reachable ensemble.

helm/templates/_metrics.tpl

@@ -0,0 +1,58 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+{{/*
+Renders metrics reporter configuration entries.
+Expects the root context as argument.
+
+From values:
+  metrics:
+    reporters:
+      prometheus:
+        port: 9249
+
+Renders:
+  metrics.reporters: prometheus
+  metrics.reporter.prometheus.port: 9249
+
+Keys already present in configurationOverrides are not rendered.
+*/}}
+{{- define "fluss.metrics.config" -}}
+{{- if .Values.metrics.enabled -}}
+{{- $config := .Values.configurationOverrides | default dict -}}
+{{- $reporters := .Values.metrics.reporters | default dict -}}
+{{- $reporterNames := keys $reporters | sortAlpha -}}
+{{- if eq (len $reporterNames) 0 -}}
+{{- fail "metrics.reporters must contain at least one reporter when metrics.enabled is true" -}}
+{{- end -}}
+{{- if not (hasKey $config "metrics.reporters") }}
+metrics.reporters: {{ join "," $reporterNames }}
+{{- end -}}
+{{- range $name := $reporterNames -}}
+{{- range $option, $value := index $reporters $name -}}
+{{- if ne $option "service" -}}
+{{- $fullKey := printf "metrics.reporter.%s.%s" $name $option -}}
+{{- if not (hasKey $config $fullKey) }}
+{{ $fullKey }}: {{ tpl (printf "%v" $value) $ }}
+{{- end -}}
+{{- end -}}
+{{- end -}}
+{{- end -}}
+{{- end -}}
+{{- end -}}
+

helm/templates/configmap.yaml

@@ -26,4 +26,5 @@ data:
   server.yaml: |
     {{- range $key, $val := .Values.configurationOverrides }}
     {{ $key }}: {{ tpl (printf "%v" $val) $ }}
-    {{- end }}
+    {{- end }}
+    {{- include "fluss.metrics.config" . | nindent 4 }}

helm/templates/svc-metrics-coordinator.yaml

@@ -0,0 +1,46 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+{{- if and .Values.metrics.enabled .Values.metrics.reporters.prometheus }}
+{{- $promSvc := .Values.metrics.reporters.prometheus.service | default dict }}
+apiVersion: v1
+kind: Service
+metadata:
+  name: {{ .Release.Name }}-coordinator-server-metrics-hs
+  labels:
+    {{- include "fluss.labels" . | nindent 4 }}
+    app.kubernetes.io/component: metrics
+    {{- with $promSvc.labels }}
+    {{- toYaml . | nindent 4 }}
+    {{- end }}
+  {{- with $promSvc.annotations }}
+  annotations:
+    {{- toYaml . | nindent 4 }}
+  {{- end }}
+spec:
+  clusterIP: None
+  type: ClusterIP
+  ports:
+    - name: {{ default "metrics" $promSvc.portName }}
+      protocol: TCP
+      port: {{ default 9249 .Values.metrics.reporters.prometheus.port }}
+      targetPort: {{ default 9249 .Values.metrics.reporters.prometheus.port }}
+  selector:
+    {{- include "fluss.selectorLabels" . | nindent 4 }}
+    app.kubernetes.io/component: coordinator
+{{- end }}

helm/templates/svc-metrics-tablet.yaml

@@ -0,0 +1,46 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+{{- if and .Values.metrics.enabled .Values.metrics.reporters.prometheus }}
+{{- $promSvc := .Values.metrics.reporters.prometheus.service | default dict }}
+apiVersion: v1
+kind: Service
+metadata:
+  name: {{ .Release.Name }}-tablet-server-metrics-hs
+  labels:
+    {{- include "fluss.labels" . | nindent 4 }}
+    app.kubernetes.io/component: metrics
+    {{- with $promSvc.labels }}
+    {{- toYaml . | nindent 4 }}
+    {{- end }}
+  {{- with $promSvc.annotations }}
+  annotations:
+    {{- toYaml . | nindent 4 }}
+  {{- end }}
+spec:
+  clusterIP: None
+  type: ClusterIP
+  ports:
+    - name: {{ default "metrics" $promSvc.portName }}
+      protocol: TCP
+      port: {{ default 9249 .Values.metrics.reporters.prometheus.port }}
+      targetPort: {{ default 9249 .Values.metrics.reporters.prometheus.port }}
+  selector:
+    {{- include "fluss.selectorLabels" . | nindent 4 }}
+    app.kubernetes.io/component: tablet
+{{- end }}