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z2/Dockerfile

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+FROM node:18
+WORKDIR /app
+COPY package.json .
+RUN npm install
+COPY . .
+EXPOSE 3000
+CMD ["node", "server.js"]

z2/README.md

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+1. Application Description
+This project is a simple full-stack web application deployed on Kubernetes.
+It allows users to submit names through a web interface and store them in a PostgreSQL database.
+The system consists of:
+
+
+A frontend (static HTML interface)
+
+
+A backend API built with Node.js (Express)
+
+
+A PostgreSQL database running as a StatefulSet with persistent storage
+
+
+The backend provides REST endpoints:
+
+
+POST /add → adds a name to the database
+
+
+GET /names → retrieves all stored names
+
+
+
+2. Containers Used
+Backend (Node.js)
+
+
+Image: docker-app-backend:latest
+
+
+Purpose: Handles API requests and communicates with the database
+
+
+Database (PostgreSQL)
+
+
+Image: postgres:15
+
+
+Purpose: Stores application data persistently
+
+
+
+3. Kubernetes Objects
+Namespace
+
+
+Name: myapp
+
+
+Used to isolate all application resources
+
+
+Deployment
+
+
+Name: backend
+
+
+Runs the Node.js backend
+
+
+Ensures availability and automatic restart of the backend container
+
+
+StatefulSet
+
+
+Name: db
+
+
+Runs PostgreSQL
+
+
+Provides stable identity and persistent storage
+
+
+PersistentVolume (PV)
+
+
+Stores PostgreSQL data on node storage
+
+
+PersistentVolumeClaim (PVC)
+
+
+Automatically created via StatefulSet
+
+
+Requests storage for database persistence
+
+
+Services
+backend-service (NodePort)
+
+
+Exposes backend externally
+
+
+Accessible at:
+http://localhost:30007
+
+
+db service (ClusterIP)
+
+
+Enables internal communication between backend and database
+
+
+Backend connects using hostname: db
+
+
+
+4. Networking
+
+
+Kubernetes DNS allows communication between differents components of the application using service names. Backend communicates with database using db and external users access backend via NodePort service
+
+
+
+5. Persistent Storage
+PostgreSQL uses:
+PersistentVolume (PV) and PersistentVolumeClaim (PVC)
+
+Using these ensures that data is not lost after pod restart and application state is preserved
+
+
+6. Container Configuration
+Backend
+
+
+Port: 3000
+
+
+Database connection:
+
+
+Host: db
+
+
+User: user
+
+
+Password: password
+
+
+Database: mydb
+
+
+
+
+Database
+
+
+Port: 5432
+
+
+This uses persistent volume for data storage
+
+
+7. Preparation
+Build backend image:
+docker build -t docker-app-backend ./backend
+
+8. Deployment
+Apply all Kubernetes resources:
+kubectl apply -f namespace.yamlkubectl apply -f deployment.yamlkubectl apply -f service.yamlkubectl apply -f statefulset.yamlkubectl apply -f db-service.yaml
+
+9. Checking Application Status
+kubectl get all -n myappkubectl get pods -n myappkubectl get svc -n myapp
+
+10. Accessing the Application
+Backend API:
+http://localhost:30007
+Frontend:
+Open frontend/index.html in a browser
+
+11. Stopping the Application
+kubectl delete -f deployment.yamlkubectl delete -f service.yamlkubectl delete -f statefulset.yamlkubectl delete -f db-service.yamlkubectl delete namespace myapp
+
+12. Removing All Resources
+kubectl delete namespace myapp
+
+13. Used Resources
+
+
+Kubernetes Documentation: https://kubernetes.io/docs/
+
+
+Docker Documentation: https://docs.docker.com/
+
+
+PostgreSQL Docker Image
+
+
+Node.js Express Framework
+
+
+
+14. Use of Artificial Intelligence
+Artificial intelligence tools were used to:
+
+
+Assist with debugging deployment issues
+
+
+Improve configuration of Kubernetes objects
+
+
+Help structure the project and documentation
+
+
+All implementation, testing, and understanding were performed independently.
+
+15. Summary
+This project demonstrates:
+
+
+Containerized web application architecture
+
+
+Kubernetes Deployment and StatefulSet usage
+
+
+Persistent storage with PVC
+
+
+Internal service communication using DNS
+
+
+External access using NodePort
+
+
+The application is fully functional and can store and retrieve data using a Kubernetes-based backend and database. AI was use strictly for learninf concepts and debugging, all coding and implementation was done independently.

z2/db-service.yaml

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+apiVersion: v1
+kind: Service
+metadata:
+  name: db
+  namespace: myapp
+spec:
+  selector:
+    app: db
+  ports:
+    - port: 5432
+      targetPort: 5432
+  clusterIP: None

z2/deployment.yaml

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+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: backend
+  namespace: myapp
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: backend
+  template:
+    metadata:
+      labels:
+        app: backend
+    spec:
+      containers:
+        - name: backend
+          image: docker-app-backend:latest
+          imagePullPolicy: Never
+          ports:
+            - containerPort: 3000
+
+

z2/init.sql

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+CREATE TABLE IF NOT EXISTS names (
+  id SERIAL PRIMARY KEY,
+  name TEXT
+);

z2/namespace.yaml

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+apiVersion: v1
+kind: Namespace
+metadata:
+  name: myapp

z2/package.json

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+{
+  "name": "backend",
+  "version": "1.0.0",
+  "main": "server.js",
+  "dependencies": {
+    "express": "^4.18.2",
+    "pg": "^8.11.3",
+    "cors": "^2.8.5"
+  }
+}

z2/prepare-app.sh

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+#!/bin/bash
+echo "Preparing..."
+docker build -t docker-app-backend ./backend

z2/server.js

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+const express = require("express");
+const cors = require("cors");
+const { Pool } = require("pg");
+
+const app = express();
+app.use(cors());
+app.use(express.json());
+
+const pool = new Pool({
+  host: "db",
+  user: "user",
+  password: "password",
+  database: "mydb",
+  port: 5432,
+});
+
+pool.query("CREATE TABLE IF NOT EXISTS names (id SERIAL PRIMARY KEY, name TEXT);");
+
+app.post("/add", async (req, res) => {
+  const { name } = req.body;
+  await pool.query("INSERT INTO names(name) VALUES($1)", [name]);
+  res.send("Added");
+});
+
+app.get("/names", async (req, res) => {
+  const result = await pool.query("SELECT * FROM names");
+  res.json(result.rows);
+});
+
+app.listen(3000, () => console.log("Server running"));
+app.get("/", (req, res) => {
+  res.send("Backend is running 🚀");
+});

z2/service.yaml

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+apiVersion: v1
+kind: Service
+metadata:
+  name: backend-service
+  namespace: myapp
+spec:
+  type: NodePort
+  selector:
+    app: backend
+  ports:
+    - port: 3000
+      targetPort: 3000
+      nodePort: 30007

z2/start-app.sh

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+#!/bin/bash
+echo "Starting..."
+
+kubectl apply -f namespace.yaml
+kubectl apply -f deployment.yaml
+kubectl apply -f service.yaml
+kubectl apply -f statefulset.yaml

z2/statefulset.yaml

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+apiVersion: v1
+kind: PersistentVolume
+metadata:
+  name: db-pv
+  namespace: myapp
+spec:
+  capacity:
+    storage: 1Gi
+  accessModes:
+    - ReadWriteOnce
+  hostPath:
+    path: "/mnt/data"
+---
+apiVersion: apps/v1
+kind: StatefulSet
+metadata:
+  name: db
+  namespace: myapp
+spec:
+  serviceName: "db"
+  replicas: 1
+  selector:
+    matchLabels:
+      app: db
+  template:
+    metadata:
+      labels:
+        app: db
+    spec:
+      containers:
+        - name: postgres
+          image: postgres:15
+          ports:
+            - containerPort: 5432
+          env:
+            - name: POSTGRES_USER
+              value: "user"
+            - name: POSTGRES_PASSWORD
+              value: "password"
+            - name: POSTGRES_DB
+              value: "mydb"
+          volumeMounts:
+            - name: db-storage
+              mountPath: /var/lib/postgresql/data
+  volumeClaimTemplates:
+    - metadata:
+        name: db-storage
+      spec:
+        accessModes: ["ReadWriteOnce"]
+        resources:
+          requests:
+            storage: 1Gi

z2/stop-app.sh

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+#!/bin/bash
+echo "Stopping..."
+
+kubectl delete -f deployment.yaml
+kubectl delete -f service.yaml
+kubectl delete -f statefulset.yaml
+kubectl delete namespace myapp