feat: Initial NFS PV usage exporter implementation

- Flask app with /usage/<pv_name> and /metrics endpoints
- 300s cache TTL with threading lock for du command
- ionice/nice for low I/O priority
- Dockerfile with gunicorn
- Helm chart with deployment, service, networkpolicy
- NetworkPolicy allows only gpulive and monitoring namespaces

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.gitignore

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+*.tgz
+__pycache__/
+*.pyc
+.env

Dockerfile

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+FROM python:3.11-slim
+
+WORKDIR /app
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    coreutils \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+COPY app.py .
+
+EXPOSE 8080
+
+CMD ["gunicorn", "--bind", "0.0.0.0:8080", "--workers", "1", "--threads", "4", "app:app"]

app.py

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+from flask import Flask
+from prometheus_client import Gauge, generate_latest, CONTENT_TYPE_LATEST
+import subprocess
+import time
+import os
+import threading
+
+app = Flask(__name__)
+
+pv_usage_bytes = Gauge('nfs_pv_usage_bytes', 'PV usage in bytes', ['pv_name'])
+pv_last_check = Gauge('nfs_pv_last_check_timestamp', 'Last check timestamp', ['pv_name'])
+
+cache = {}
+CACHE_TTL = 300
+du_lock = threading.Lock()  # 동시 du 방지
+
+def get_pv_usage(pv_name):
+    now = time.time()
+    
+    # 캐시 확인 (락 없이)
+    if pv_name in cache and now - cache[pv_name]['time'] < CACHE_TTL:
+        return cache[pv_name]['bytes']
+    
+    # du는 한 번에 하나만
+    with du_lock:
+        # 락 획득 후 다시 캐시 확인
+        if pv_name in cache and time.time() - cache[pv_name]['time'] < CACHE_TTL:
+            return cache[pv_name]['bytes']
+        
+        path = f"/mnt/pvs/{pv_name}"
+        if not os.path.exists(path):
+            return None
+        
+        result = subprocess.run(
+            ['ionice', '-c', '3', 'nice', '-n', '19', 'du', '-sb', path],
+            capture_output=True, text=True, timeout=300
+        )
+        
+        if result.returncode != 0:
+            return None
+        
+        usage = int(result.stdout.split()[0])
+        cache[pv_name] = {'bytes': usage, 'time': time.time()}
+        pv_usage_bytes.labels(pv_name=pv_name).set(usage)
+        pv_last_check.labels(pv_name=pv_name).set(time.time())
+        
+        return usage
+
+@app.route('/usage/<pv_name>')
+def usage(pv_name):
+    result = get_pv_usage(pv_name)
+    if result is None:
+        return {'error': 'PV not found or timeout'}, 404
+    return {'pv_name': pv_name, 'bytes': result}
+
+@app.route('/metrics')
+def metrics():
+    return generate_latest(), 200, {'Content-Type': CONTENT_TYPE_LATEST}
+
+if __name__ == '__main__':
+    app.run(host='0.0.0.0', port=8080, threaded=True)

chart/Chart.yaml

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+apiVersion: v2
+name: nfs-usage-exporter
+description: NFS PV usage metrics exporter for Prometheus
+type: application
+version: 1.0.0
+appVersion: "1.0.0"

chart/templates/deployment.yaml

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+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: {{ .Chart.Name }}
+  labels:
+    app: {{ .Chart.Name }}
+spec:
+  replicas: {{ .Values.replicaCount }}
+  selector:
+    matchLabels:
+      app: {{ .Chart.Name }}
+  template:
+    metadata:
+      labels:
+        app: {{ .Chart.Name }}
+    spec:
+      nodeSelector:
+        {{- toYaml .Values.nodeSelector | nindent 8 }}
+      containers:
+      - name: exporter
+        image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
+        imagePullPolicy: {{ .Values.image.pullPolicy }}
+        ports:
+        - containerPort: 8080
+          name: metrics
+        volumeMounts:
+        - name: nfs-root
+          mountPath: /mnt/pvs
+          readOnly: true
+        resources:
+          {{- toYaml .Values.resources | nindent 10 }}
+      volumes:
+      - name: nfs-root
+        nfs:
+          server: {{ .Values.nfs.server }}
+          path: {{ .Values.nfs.path }}
+          readOnly: true

chart/templates/networkpolicy.yaml

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+{{- if .Values.networkPolicy.enabled }}
+apiVersion: networking.k8s.io/v1
+kind: NetworkPolicy
+metadata:
+  name: {{ .Chart.Name }}
+  labels:
+    app: {{ .Chart.Name }}
+spec:
+  podSelector:
+    matchLabels:
+      app: {{ .Chart.Name }}
+  policyTypes:
+  - Ingress
+  ingress:
+  - from:
+    {{- range .Values.networkPolicy.allowedNamespaces }}
+    - namespaceSelector:
+        matchLabels:
+          kubernetes.io/metadata.name: {{ . }}
+    {{- end }}
+    ports:
+    - protocol: TCP
+      port: 8080
+{{- end }}

chart/templates/service.yaml

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+apiVersion: v1
+kind: Service
+metadata:
+  name: {{ .Chart.Name }}
+  labels:
+    app: {{ .Chart.Name }}
+  annotations:
+    prometheus.io/scrape: "true"
+    prometheus.io/port: "8080"
+    prometheus.io/path: "/metrics"
+spec:
+  type: {{ .Values.service.type }}
+  ports:
+  - port: {{ .Values.service.port }}
+    targetPort: 8080
+    protocol: TCP
+    name: metrics
+  selector:
+    app: {{ .Chart.Name }}

chart/values.yaml

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+replicaCount: 1
+
+image:
+  repository: harbor.inje-private.com/infra/nfs-usage-exporter
+  tag: "v1.0.0"
+  pullPolicy: IfNotPresent
+
+service:
+  type: ClusterIP
+  port: 8080
+
+resources:
+  limits:
+    cpu: 500m
+    memory: 256Mi
+  requests:
+    cpu: 100m
+    memory: 128Mi
+
+nodeSelector:
+  nodegroup: nd
+
+nfs:
+  server: "192.168.0.54"
+  path: "/GJ_SHARE_FS6/39197c35-6247-4ece-bc74-d9460a757a04"
+
+networkPolicy:
+  enabled: true
+  allowedNamespaces:
+    - gpulive
+    - monitoring

requirements.txt

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+flask==3.0.0
+prometheus_client==0.19.0
+gunicorn==21.2.0