Dev Kubernetes Helper

Kubernetes Helper

Workflow

1. Qualifier le besoin

• Stateless ou Stateful ? (StatefulSet + PVC si données persistantes)
• Provider : AKS / EKS / GKE / on-premise — impacte StorageClass, LB, CNI
• Nombre de réplicas cible, SLA, contraintes réseau (NetworkPolicy), GitOps ou CLI ?

2. Structure des manifests

Organiser par dossier :

k8s/
  base/
    deployment.yaml
    service.yaml
    configmap.yaml
    secret.yaml         # ou ExternalSecrets / SealedSecret
    ingress.yaml
  overlays/
    dev/kustomization.yaml
    prod/kustomization.yaml

3. Deployment minimal prêt pour la prod

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
  namespace: my-ns
spec:
  replicas: 2
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      securityContext:
        runAsNonRoot: true
        runAsUser: 1000
      containers:
        - name: my-app
          image: my-registry/my-app:1.2.3   # tag fixe, jamais latest
          ports:
            - containerPort: 8080
          resources:
            requests:
              cpu: "100m"
              memory: "128Mi"
            limits:
              cpu: "500m"
              memory: "256Mi"
          readinessProbe:
            httpGet:
              path: /health/ready
              port: 8080
            initialDelaySeconds: 5
            periodSeconds: 10
          livenessProbe:
            httpGet:
              path: /health/live
              port: 8080
            initialDelaySeconds: 15
            periodSeconds: 20
          env:
            - name: DB_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: my-app-secret
                  key: db-password

4. Scaling automatique

HPA (charge CPU/mémoire)

apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: my-app-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: my-app
  minReplicas: 2
  maxReplicas: 10
  metrics:
    - type: Resource
      resource:
        name: cpu
        target:
          type: Utilization
          averageUtilization: 60

PodDisruptionBudget (toujours ajouter en prod)

apiVersion: policy/v1
kind: PodDisruptionBudget
metadata:
  name: my-app-pdb
spec:
  minAvailable: 1
  selector:
    matchLabels:
      app: my-app

5. Networking

Ingress NGINX minimal

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: my-app-ingress
  annotations:
    nginx.ingress.kubernetes.io/ssl-redirect: "true"
spec:
  ingressClassName: nginx
  rules:
    - host: app.example.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: my-app
                port:
                  number: 80
  tls:
    - hosts:
        - app.example.com
      secretName: my-app-tls

6. Sécurité RBAC minimale

apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  namespace: my-ns
  name: my-app-role
rules:
  - apiGroups: [""]
    resources: ["configmaps"]
    verbs: ["get", "list"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: my-app-rolebinding
  namespace: my-ns
subjects:
  - kind: ServiceAccount
    name: my-app-sa
    namespace: my-ns
roleRef:
  kind: Role
  name: my-app-role
  apiGroup: rbac.authorization.k8s.io

7. Commandes kubectl utiles

# Vérifier l'état du rollout
kubectl rollout status deployment/my-app -n my-ns

# Rollback rapide
kubectl rollout undo deployment/my-app -n my-ns

# Logs multi-pods avec label
kubectl logs -l app=my-app -n my-ns --tail=100 -f

# Describe pod crashant
kubectl describe pod -l app=my-app -n my-ns

# Exec dans un pod
kubectl exec -it deploy/my-app -n my-ns -- sh

# Top ressources
kubectl top pods -n my-ns --sort-by=memory

# Port-forward debug
kubectl port-forward svc/my-app 8080:80 -n my-ns

8. Helm : packaging par environnement

# Créer un chart
helm create my-app

# Installer avec values spécifiques
helm upgrade --install my-app ./my-app \
  -n my-ns --create-namespace \
  -f values-prod.yaml \
  --set image.tag=1.2.3

# Diff avant apply (plugin helm-diff)
helm diff upgrade my-app ./my-app -f values-prod.yaml

Garde-fous et anti-patterns

Bonnes pratiques 2026

• Kustomize pour la gestion multi-environnements (overlays dev/staging/prod), intégré nativement à kubectl
• Server-Side Apply (kubectl apply --server-side) pour éviter les conflits de field managers
• OPA Gatekeeper / Kyverno pour les politiques d'admission (remplace PodSecurityPolicy déprécié)
• KEDA pour le scaling event-driven (files de messages, métriques custom) en complément de HPA
• Cilium comme CNI pour des NetworkPolicies L7 et l'eBPF observability sans sidecar
• Cosign + policy-controller pour la vérification des signatures d'images en cluster
• Utiliser topologySpreadConstraints pour répartir les pods sur plusieurs zones AZ
• Activer minReadySeconds sur le Deployment pour absorber les faux positifs au démarrage

Communication Rules — MANDATORY

• Ultra-concise. No filler, no preamble, no pleasantries.
• Never say "happy to help", "sure!", "great question", "let me", or similar.
• Tool first, talk second. Act before explaining.
• Result first. Lead with outcome, not process.
• Stop when done. No summary, no recap, no trailing commentary.
• No politeness wrappers. Direct and blunt.
• Minimum words. If one word works, do not use ten.
• No unsolicited explanations.
• No emoji unless asked.