Assignment

Z2/app/Dockerfile

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

Z2/app/package.json

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+{
+  "name": "k8s-app",
+  "version": "1.0.0",
+  "main": "server.js",
+  "dependencies": {
+    "express": "^4.18.2",
+    "pg": "^8.11.0"
+  }
+}

Z2/app/server.js

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+const express = require("express");
+const { Pool } = require("pg");
+
+const app = express();
+
+const pool = new Pool({
+  host: "postgres-service",
+  user: "postgres",
+  password: "postgres",
+  database: "testdb",
+  port: 5432,
+});
+
+app.get("/", async (req, res) => {
+  try {
+    const result = await pool.query("SELECT NOW()");
+    res.send("DB Time: " + result.rows[0].now);
+  } catch (err) {
+    res.send("Database not ready");
+  }
+});
+
+app.listen(3000, () => {
+  console.log("Server running on port 3000");
+});

Z2/k8s/deployment.yaml

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+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: web-app
+  namespace: my-app-namespace
+spec:
+  replicas: 2
+  selector:
+    matchLabels:
+      app: web-app
+  template:
+    metadata:
+      labels:
+        app: web-app
+    spec:
+      containers:
+        - name: web-app
+          image: my-web-app:latest
+          imagePullPolicy: Never
+          ports:
+            - containerPort: 3000

Z2/k8s/namespace.yaml

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+apiVersion: v1
+kind: Namespace
+metadata:
+  name: my-app-namespace

Z2/k8s/service.yaml

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+apiVersion: v1
+kind: Service
+metadata:
+  name: web-service
+  namespace: my-app-namespace
+spec:
+  type: NodePort
+  selector:
+    app: web-app
+  ports:
+    - port: 80
+      targetPort: 3000
+      nodePort: 30007

Z2/k8s/statefulset.yaml

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+apiVersion: v1
+kind: PersistentVolume
+metadata:
+  name: postgres-pv
+spec:
+  capacity:
+    storage: 1Gi
+  accessModes:
+    - ReadWriteOnce
+  hostPath:
+    path: "/mnt/s/docker/Z2/data/postgres"
+---
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: postgres-pvc
+  namespace: my-app-namespace
+spec:
+  accessModes:
+    - ReadWriteOnce
+  resources:
+    requests:
+      storage: 1Gi
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: postgres-service
+  namespace: my-app-namespace
+spec:
+  ports:
+    - port: 5432
+  clusterIP: None
+  selector:
+    app: postgres
+---
+apiVersion: apps/v1
+kind: StatefulSet
+metadata:
+  name: postgres
+  namespace: my-app-namespace
+spec:
+  serviceName: "postgres-service"
+  replicas: 1
+  selector:
+    matchLabels:
+      app: postgres
+  template:
+    metadata:
+      labels:
+        app: postgres
+    spec:
+      containers:
+        - name: postgres
+          image: postgres:15
+          env:
+            - name: POSTGRES_PASSWORD
+              value: postgres
+            - name: POSTGRES_DB
+              value: testdb
+          ports:
+            - containerPort: 5432
+          volumeMounts:
+            - name: postgres-storage
+              mountPath: /var/lib/postgresql/data
+  volumeClaimTemplates:
+    - metadata:
+        name: postgres-storage
+      spec:
+        accessModes: ["ReadWriteOnce"]
+        resources:
+          requests:
+            storage: 1Gi

Z2/scripts/prepare-app.sh

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+#!/bin/bash
+
+echo "Building Docker image..."
+docker build -t my-web-app:latest ./app
+
+echo "Creating volume directory..."
+mkdir -p ./data/postgres
+
+echo "Done."

Z2/scripts/start-app.sh

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+#!/bin/bash
+
+echo "Creating namespace..."
+kubectl apply -f k8s/namespace.yaml
+
+echo "Deploying database..."
+kubectl apply -f k8s/statefulset.yaml
+
+echo "Deploying web app..."
+kubectl apply -f k8s/deployment.yaml
+
+echo "Creating service..."
+kubectl apply -f k8s/service.yaml
+
+echo "App started!"

Z2/scripts/stop-app.sh

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+#!/bin/bash
+
+echo "Deleting all resources..."
+kubectl delete namespace my-app-namespace
+
+echo "App stopped!"