z2

z2/README.md

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+# Visitor Counter Application
+
+## Description of the Application
+This application is designed to count the number of visits to a webpage. It utilizes Flask for the backend, Apache for serving static web content, and Redis for storing visitor counts.
+
+## List of Containers Used
+
+- **Backend Container**: Built using Flask, this container handles API requests and updates visitor counts in Redis.
+- **Web Container**: Built using Apache, this container serves static HTML content.
+- **Redis Container**: Uses the official Redis image to store visitor counts persistently.
+
+## List of Kubernetes Objects
+
+- **Deployments**:
+  - **Backend Deployment**: Manages the backend Flask application.
+  - **Web Deployment**: Manages the web Apache server.
+- **Services**:
+  - **Backend Service**: Exposes the backend application on a specific port.
+  - **Web Service**: Exposes the web server on a specific port.
+  - **Redis Service**: Provides access to the Redis database.
+- **StatefulSet**:
+  - **Redis StatefulSet**: Ensures persistent storage for Redis data.
+- **PersistentVolumeClaim (PVC)** and **PersistentVolume (PV)**:
+  - Used for providing persistent storage to Redis.
+
+## Virtual Networks and Named Volumes
+
+- **Virtual Networks**: Kubernetes automatically manages pod-to-pod communication within a cluster.
+- **Named Volumes**: Used for persistent storage in Redis, ensuring data is retained across pod restarts.
+
+## Container Configuration
+
+- **Backend Container**: Configured to listen on port 5000 and connect to Redis for storing visitor counts.
+- **Web Container**: Configured to serve static HTML content on port 80.
+- **Redis Container**: Configured to store data persistently using a PersistentVolumeClaim.
+
+## Instructions to Prepare, Run, Pause, and Delete the Application
+
+1. **Prepare the Application**:
+   Run the `prepare-app.sh` script to build Docker images and load them into Minikube.
+
+./prepare-app.sh
+
+
+2. **Run the Application**:
+Run the `start-app.sh` script to create all necessary Kubernetes objects and start the application.
+./start-app.sh
+
+
+3. **Pause the Application**:
+You can pause the application by scaling down deployments to zero replicas:
+
+kubectl scale deployment backend-deployment --replicas=0
+kubectl scale deployment web-deployment --replicas=0
+
+
+4. **Delete the Application**:
+Run the `stop-app.sh` script to delete all Kubernetes objects and stop the application.
+./stop-app.sh
+
+
+## Instructions to View the Application on the Web
+
+1. **Access the Web Service**:
+Use Minikube to access the web service:
+
+minikube service web-service --url
+
+This will output a URL that you can use to view the application in your web browser by ctrl+clicking on the link.

z2/backend/Dockerfile

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+FROM python:3.9-slim
+
+WORKDIR /app
+
+COPY app.py /app/
+
+RUN pip install flask redis flask-cors
+
+EXPOSE 5000
+
+CMD ["python", "app.py"]

z2/backend/app.py

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+from flask import Flask, jsonify
+from flask_cors import CORS
+import redis
+
+app = Flask(__name__)
+CORS(app)
+
+# Connect to Redis (running in a separate container and foldr)
+redis_client = redis.StrictRedis(host='redis', port=6379, decode_responses=True)
+
+@app.route('/counter', methods=['GET'])
+def counter():
+    # Increment visitor count in Redis
+    visits = redis_client.incr('visits')
+    return jsonify({"visits": visits})
+
+if __name__ == '__main__':
+    app.run(host='0.0.0.0', port=5000)

z2/check.sh

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+#!/bin/bash
+
+# list all namespaces
+echo "Namespaces:"
+kubectl get namespaces
+
+# list all statefulsets 
+echo "\nStatefulSets:"
+kubectl get statefulsets 
+
+# list all services 
+echo "\nServices:"
+kubectl get services
+
+
+# list all deployments 
+echo "\nDeployments:"
+kubectl get deployments 
+
+# list all pods 
+echo "\nPods:"
+kubectl get pods
+

z2/compose.yaml

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+version: '3.8'
+
+services:
+  web:
+    build: ./web
+    ports:
+      - "5000:80"
+    depends_on:
+      - backend
+    restart: always
+
+  backend:
+    build: ./backend
+    ports:
+      - "5001:5000"
+    depends_on:
+      - redis
+    restart: always
+
+  redis:
+    image: redis:alpine
+    command: ["redis-server", "--appendonly", "yes"]
+    volumes:
+      - redis_data:/data
+    restart: always
+
+volumes:
+  redis_data:

z2/deployment.yaml

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+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: backend-deployment
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: backend-app
+  template:
+    metadata:
+      labels:
+        app: backend-app
+    spec:
+      containers:
+      - name: backend-container
+        image: backend:latest
+        imagePullPolicy: IfNotPresent #uses local images if available
+        ports:
+        - containerPort: 5000

z2/prepare-app.sh

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+#!/bin/bash
+
+# build Docker images for backend and web
+docker build -t backend:latest ./backend
+docker build -t web:latest ./web
+
+# load images into minikube
+minikube image load backend:latest
+minikube image load web:latest

z2/redis-service.yaml

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+apiVersion: v1
+kind: Service
+metadata:
+  name: redis-service
+spec:
+  selector:
+    app: redis-app # This must match the pod label in StatefulSet.
+  ports:
+  - name: redis-port
+    port: 6379 # External port for Redis.
+    targetPort: 6379 # Internal container port.

z2/service.yaml

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+apiVersion: v1
+kind: Service
+metadata:
+  name: backend-service
+spec:
+  selector:
+    app: backend-app
+  ports:
+  - name: http
+    port: 5000
+    targetPort: 5000
+  type: NodePort

z2/start-app.sh

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+#!/bin/bash
+
+# start minikube
+minikube start
+
+# apply all Kubernetes YAML files
+kubectl apply -f backend-deployment.yaml
+kubectl apply -f web-deployment.yaml
+kubectl apply -f statefulset.yaml
+kubectl apply -f backend-service.yaml
+kubectl apply -f web-service.yaml
+kubectl apply -f redis-service.yaml
+
+# Output web service URL
+minikube service web-service --url

z2/statefulset.yaml

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+apiVersion: apps/v1
+kind: StatefulSet
+metadata:
+  name: redis-statefulset
+spec:
+  serviceName: "redis-service"
+  replicas: 1
+  selector:
+    matchLabels:
+      app: redis-app
+  template:
+    metadata:
+      labels:
+        app: redis-app
+    spec:
+      containers:
+      - name: redis-container
+        image: redis:alpine # Redis image.
+        ports:
+        - containerPort: 6379 # Redis default port.
+        volumeMounts:
+        - name: redis-storage-volume # Mount persistent volume.
+          mountPath: /data # Redis data directory.
+  volumeClaimTemplates:
+  - metadata:
+      name: redis-storage-volume # Persistent Volume Claim.
+    spec:
+      accessModes: ["ReadWriteOnce"]
+      resources:
+        requests:
+          storage: 1Gi # Persistent storage size.

z2/stop-app.sh

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+#!/bin/bash
+
+# delete all Kubernetes objects
+kubectl delete -f backend-deployment.yaml
+kubectl delete -f web-deployment.yaml
+kubectl delete -f statefulset.yaml
+kubectl delete -f backend-service.yaml
+kubectl delete -f web-service.yaml
+kubectl delete -f redis-service.yaml
+
+# stop minikube
+minikube stop

z2/web-deployment.yaml

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+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: web-deployment
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: web-app
+  template:
+    metadata:
+      labels:
+        app: web-app
+    spec:
+      containers:
+      - name: web-container
+        image: web:latest
+        imagePullPolicy: IfNotPresent #same thing uses local image if any
+        ports:
+        - containerPort: 80

z2/web-service.yaml

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+apiVersion: v1
+kind: Service
+metadata:
+  name: web-service
+spec:
+  selector:
+    app: web-app
+  ports:
+  - name: http
+    port: 80
+    targetPort: 80
+  type: NodePort

z2/web/Dockerfile

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+FROM httpd:2.4
+
+# Copies your static HTML file into the Apache document root
+COPY index.html /usr/local/apache2/htdocs/
+
+# Add a proxy configuration for /counter
+RUN echo "ProxyPass /counter http://backend-service:5000/counter" >> /usr/local/apache2/conf/httpd.conf
+RUN echo "ProxyPassReverse /counter http://backend-service:5000/counter" >> /usr/local/apache2/conf/httpd.conf
+
+
+EXPOSE 80

z2/web/index.html

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+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1.0">
+  <title>Visitor Counter</title>
+</head>
+<body>
+  <h1>Welcome to the Visitor Counter App!</h1>
+  <h2>Made by ALI</h2>
+  <h3>Also made for assinment 1</h3>
+  <p>This page has been visited <span id="counter">0</span> times.</p>
+
+  <script>
+    async function updateCounter() {
+      try {
+        const response = await fetch('/counter');
+        const data = await response.json();
+        document.getElementById('counter').textContent = data.visits;
+      } catch (error) {
+        console.error('Error fetching counter:', error);
+      }
+    }
+
+    updateCounter();
+  </script>
+</body>
+</html>