Ahmed Baha Eddine Alimi - B23-SD-01 [Lab12 + Bonus Task]

[3llimi]

Lab 12 — ConfigMaps & Persistent Volumes

What was done:

• Added file-based visits counter to Python app with thread-safe threading.Lock() to prevent race conditions; counter reads/writes to VISITS_FILE env var path (default /data/visits) with graceful fallback to 0 on missing or corrupted file
• Added GET /visits endpoint returning current count and timestamp; updated GET / to include visits field and new endpoint in the endpoints list
• Updated monitoring/docker-compose.yml to use bind mount ./data:/data instead of named volume — named volumes are owned by root on creation, causing PermissionError since container runs as non-root appuser; confirmed persistence across docker compose restart (counter continued from 3 → 4)
• Created k8s/devops-python/files/config.json with app name, environment, feature flags, and settings; added templates/configmap.yaml with two ConfigMaps — file ConfigMap using .Files.Get mounted at /config/config.json, and env ConfigMap with 4 keys injected via envFrom.configMapRef; verified both inside pod
• Created k8s/devops-python/templates/pvc.yaml with 100Mi ReadWriteOnce claim using default storage class; mounted at /data in deployment; confirmed PVC persistence — visits counter preserved at 4 after kubectl delete pod

Bonus:

• Tested ConfigMap hot reload — directory mount auto-updates in ~60 seconds via kubelet sync period without pod restart; confirmed by editing ConfigMap via kubectl edit and observing environment: staging appear in mounted file after 60s
• Documented subPath limitation: files mounted via subPath are copied once at pod creation and never auto-update because they bypass the symlink mechanism used for directory mounts
• Implemented checksum annotation pattern in deployment template — checksum/config: {{ include (print $.Template.BasePath "/configmap.yaml") . | sha256sum }} triggers rolling pod restart whenever ConfigMap content changes via helm upgrade, ensuring pods always reload with fresh configuration