zkt26/z2/README.md

Vigimétéo – Kubernetes Deployment (z2)

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1. Application description

Vigimétéo is a weather monitoring web application.
Users can log in, browse weather stations, consult meteorological data (wind, temperature, pressure…) and manage objects depending on their role.

The stack is made of three services:

• A React frontend served by Nginx
• A Java / Vert.x REST backend that exposes the API
• A PostgreSQL database that stores all data

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2. Containers used

Container	Image	Role
vigimeteo-frontend	vigimeteo-frontend:latest (built from Front-end/Dockerfile)	React SPA built with Vite, served by Nginx on port 80
vigimeteo-backend	vigimeteo-backend:latest (built from Back-end/Dockerfile)	Java 17 / Vert.x REST API on port 8888. Connects to PostgreSQL using environment variables
postgres	postgres:17-alpine	PostgreSQL database. Automatically runs init.sql on first start to create tables and insert seed data
busybox (init)	busybox:1.36	Temporary init container inside the backend pod. Waits until PostgreSQL port 5432 is open before letting the backend start

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3. Kubernetes objects

Kind	Name	Description
Namespace	vigimeteo	Isolates all objects of this application from the rest of the cluster
PersistentVolume	vigimeteo-db-pv	1 Gi storage volume mapped to ~/vigimeteo-db-data on the host node
PersistentVolumeClaim	vigimeteo-db-pvc	Request for storage, bound to the PV above. Used by the StatefulSet
ConfigMap	vigimeteo-db-init	Holds the SQL init script (init.sql). Mounted into the PostgreSQL container
StatefulSet	vigimeteo-db	Manages the PostgreSQL pod. Provides a stable name and stable storage
Deployment	vigimeteo-backend	Manages 2 replicas of the Vert.x backend
Deployment	vigimeteo-frontend	Manages 2 replicas of the Nginx/React frontend
Service (Headless)	vigimeteo-db	Gives the PostgreSQL pod a stable DNS name: vigimeteo-db.vigimeteo.svc.cluster.local
Service (NodePort)	vigimeteo-backend-service	Exposes the backend API on port 30888 (accessible from the host)
Service (NodePort)	vigimeteo-frontend-service	Exposes the frontend on port 30500 (accessible from the host)

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4. Networks and volumes

Network

Kubernetes creates a virtual internal network for the vigimeteo namespace automatically.

• Pods communicate internally using DNS service names (e.g. vigimeteo-db.vigimeteo.svc.cluster.local).
• The frontend and backend are exposed externally via NodePort services.

Access	Address
Frontend (browser)	http://localhost:30500
Backend API	http://localhost:30888
Database (internal only)	vigimeteo-db.vigimeteo.svc.cluster.local:5432

Volume

Name	Type	Host path	Used by
vigimeteo-db-pv	PersistentVolume (hostPath)	~/vigimeteo-db-data	PostgreSQL StatefulSet

The volume is created by prepare-app.sh with mkdir -p ~/vigimeteo-db-data.
It persists data even after the application is stopped.

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5. Container configuration

Backend – environment variables

The backend connects to the database using these environment variables set in deployment.yaml:

Variable	Value
DB_HOST	vigimeteo-db.vigimeteo.svc.cluster.local
DB_PORT	5432
DB_NAME	postgres
DB_USER	postgres
DB_PASSWORD	admin

Backend – init container

To avoid connection errors on startup, a busybox init container runs first and waits until PostgreSQL accepts connections on port 5432:

until nc -z vigimeteo-db.vigimeteo.svc.cluster.local 5432; do sleep 3; done

Database – init script

The ConfigMap vigimeteo-db-init contains init.sql and is mounted into /docker-entrypoint-initdb.d/ inside the PostgreSQL container. PostgreSQL automatically runs all .sql files in that folder on first startup.

Images

Both images are built locally with imagePullPolicy: IfNotPresent so Kubernetes never tries to pull them from a registry.

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6. How to run the application

Prerequisites

• docker installed and running
• kubectl configured and connected to a cluster
• For Minikube: run eval $(minikube docker-env) first so images are built inside Minikube's daemon

Step 1 – Prepare (first time only)

bash prepare-app.sh

This creates the PV host directory and builds the two Docker images.

Step 2 – Start

bash start-app.sh

Applies all Kubernetes objects in the correct order and waits for PostgreSQL to be ready before deploying the backend.

Step 3 – Pause / restart

There is no "pause" in Kubernetes. To stop traffic you can scale down replicas:

kubectl scale deployment vigimeteo-backend vigimeteo-frontend --replicas=0 -n vigimeteo

To restart:

kubectl scale deployment vigimeteo-backend vigimeteo-frontend --replicas=2 -n vigimeteo

Step 4 – Delete

bash stop-app.sh

This deletes the namespace (which removes all objects inside it) and the PersistentVolume.
The data folder ~/vigimeteo-db-data is not deleted. To fully clean up:

rm -rf ~/vigimeteo-db-data

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7. How to access the application

Once the app is started, open your browser at:

http://localhost:30500

Test credentials

Role	Email	Password
Admin	admin@a.com	azertyuiop
Complexe user	complexe@gmail.com	azertyuiop
Regular user	user@gmail.com	azertyuiop

Verify everything is running

kubectl get all -n vigimeteo

All pods should show 1/1 Running.

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Troubleshooting

Pod stays Pending → The PVC is not bound. Run kubectl describe pod -n vigimeteo <pod-name> and check the events. Make sure ~/vigimeteo-db-data exists.

Backend CrashLoopBackOff → Check logs with kubectl logs -n vigimeteo deployment/vigimeteo-backend. Usually a DB connection issue.

Images not found → For Minikube, run eval $(minikube docker-env) before prepare-app.sh.