Cloud Computing Notes — B.Tech IT Sem 5

Cloud Computing — Introduction

Cloud Computing internet ke through on-demand computing resources (servers, storage, databases, networking, software) deliver karna hai — pay-as-you-go model mein.

NIST Definition ke 5 Characteristics:

1. On-demand self-service
2. Broad network access
3. Resource pooling (multi-tenancy)
4. Rapid elasticity
5. Measured service (billing by use)

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1. Cloud Service Models

IaaS — Infrastructure as a Service

Virtual hardware provide karta hai — servers, storage, networking.

| Provider | Service | Use Case | |----------|---------|----------| | AWS | EC2 | Virtual servers | | AWS | S3 | Object storage | | Azure | Virtual Machines | Windows/Linux VMs | | GCP | Compute Engine | Custom VMs |

You manage: OS, runtime, apps, data Provider manages: Physical hardware, networking, hypervisor

PaaS — Platform as a Service

Development platform — OS + runtime + middleware managed.

| Provider | Service | |----------|---------| | Google | App Engine | | Heroku | Full PaaS | | AWS | Elastic Beanstalk | | Azure | App Service |

You manage: Application code + data only

SaaS — Software as a Service

Ready-to-use software over internet.

Examples: Gmail, Google Docs, Salesforce, Zoom, Slack, Office 365

You manage: Your data + configuration only

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2. Cloud Deployment Models

| Model | Description | Example | |-------|-------------|---------| | Public Cloud | Shared infrastructure, internet accessible | AWS, Azure, GCP | | Private Cloud | Dedicated infrastructure, org-only | On-premises VMware | | Hybrid Cloud | Public + Private connected | AWS + on-prem DC | | Community Cloud | Shared among similar orgs | Government cloud |

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3. AWS Core Services

Compute

EC2 (Elastic Compute Cloud)
├── Instance Types: t2.micro, m5.large, c5.xlarge
├── AMI (Amazon Machine Image) — OS snapshot
├── Security Groups — virtual firewall
└── Elastic IP — static public IP

Lambda (Serverless)
├── Event-driven functions
├── Pay per 100ms execution
├── Max 15 min runtime
└── Triggers: S3, API Gateway, DynamoDB streams

Storage

S3 (Simple Storage Service)
├── Object storage — unlimited capacity
├── Storage classes: Standard, IA, Glacier
├── Versioning, lifecycle policies
└── Static website hosting

EBS (Elastic Block Store)
└── Persistent disk for EC2 instances

RDS (Relational Database Service)
└── Managed MySQL, PostgreSQL, Aurora

Networking

VPC (Virtual Private Cloud)
├── Subnet — public (internet) / private
├── Internet Gateway — public subnet internet access
├── NAT Gateway — private subnet outbound
├── Route Tables — traffic routing rules
└── Security Groups + NACLs

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4. Docker — Containerization

# Dockerfile Example — Node.js App
FROM node:18-alpine          # Base image
WORKDIR /app                 # Working directory
COPY package*.json ./        # Copy dependencies
RUN npm install              # Install packages
COPY . .                     # Copy source code
EXPOSE 3000                  # Port to expose
CMD ["node", "server.js"]    # Start command

Essential Docker Commands:

# Image operations
docker build -t myapp:v1 .       # Build image
docker images                    # List images
docker pull nginx                # Pull from Docker Hub
docker push myapp:v1             # Push to registry

# Container operations
docker run -d -p 8080:3000 myapp:v1    # Run detached, port mapping
docker ps                               # Running containers
docker stop <container-id>             # Stop container
docker logs <container-id>             # View logs
docker exec -it <container-id> sh      # Enter container shell
docker rm <container-id>               # Remove container

# Docker Compose
docker-compose up -d           # Start all services
docker-compose down            # Stop and remove
docker-compose logs -f         # Follow logs

Docker Compose — Multi-container App:

version: '3.8'
services:
  web:
    build: .
    ports: ["3000:3000"]
    environment:
      - NODE_ENV=production
    depends_on: [db, redis]

  db:
    image: postgres:15
    environment:
      POSTGRES_DB: myapp
      POSTGRES_PASSWORD: secret
    volumes:
      - pgdata:/var/lib/postgresql/data

  redis:
    image: redis:7-alpine
    ports: ["6379:6379"]

volumes:
  pgdata:

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5. Kubernetes (K8s) — Container Orchestration

Architecture:

Control Plane (Master)           Worker Nodes
├── API Server               ├── kubelet (agent)
├── etcd (state store)       ├── kube-proxy (networking)
├── Scheduler                └── Container Runtime (Docker/containerd)
└── Controller Manager

Pod = smallest deployable unit (1+ containers)

Core K8s Objects:

# Deployment — manages replica set of pods
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: myapp
        image: myapp:v1
        ports:
        - containerPort: 3000
        resources:
          requests:
            memory: "128Mi"
            cpu: "250m"
          limits:
            memory: "256Mi"
            cpu: "500m"
---
# Service — expose deployment
apiVersion: v1
kind: Service
metadata:
  name: myapp-service
spec:
  selector:
    app: myapp
  ports:
  - port: 80
    targetPort: 3000
  type: LoadBalancer

kubectl Commands:

kubectl get pods                      # List pods
kubectl describe pod <pod-name>       # Pod details
kubectl logs <pod-name>               # Pod logs
kubectl exec -it <pod> -- /bin/bash   # Shell into pod
kubectl apply -f deployment.yaml      # Apply config
kubectl delete -f deployment.yaml     # Delete resources
kubectl scale deploy myapp --replicas=5  # Scale up
kubectl rollout status deploy/myapp   # Check rollout
kubectl rollout undo deploy/myapp     # Rollback

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6. Serverless — AWS Lambda

# Lambda Function — Python
import json
import boto3

def lambda_handler(event, context):
    # Parse input
    name = event.get('name', 'World')

    # Use AWS services
    s3 = boto3.client('s3')
    # s3.put_object(Bucket='mybucket', Key='file.txt', Body='data')

    return {
        'statusCode': 200,
        'body': json.dumps({'message': f'Hello {name}!'})
    }

Lambda Triggers:

• API Gateway (REST/HTTP API)
• S3 (object created/deleted)
• DynamoDB Streams
• SQS (message queue)
• CloudWatch Events (scheduled)
• SNS (notifications)

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7. Cloud Security

Shared Responsibility Model:

AWS Responsible For:                 You Responsible For:
├── Physical security                ├── IAM users & permissions
├── Hardware maintenance             ├── Application security
├── Network infrastructure           ├── Data encryption
└── Hypervisor security             └── OS patching (IaaS)

IAM Best Practices:

{
  "Version": "2012-10-17",
  "Statement": [{
    "Effect": "Allow",
    "Action": ["s3:GetObject", "s3:PutObject"],
    "Resource": "arn:aws:s3:::mybucket/*"
  }]
}

• Least privilege principle
• MFA for all users
• Rotate access keys regularly
• Use roles, not access keys in EC2

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Exam Important Questions

1. IaaS, PaaS, SaaS mein difference explain karo with examples
2. Public, Private aur Hybrid cloud compare karo
3. Docker container aur Virtual Machine mein kya fark hai?
4. Kubernetes architecture explain karo (Control Plane + Worker Nodes)
5. AWS VPC kya hai? Subnets, Security Groups explain karo
6. Serverless computing ke advantages aur disadvantages kya hain?
7. Cloud security ke best practices kya hain?
8. Docker Compose ka use kya hai?

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Viva Questions

Q: Cloud computing mein elasticity aur scalability mein kya fark hai? A: Elasticity = automatically scale up/down based on load (AWS Auto Scaling). Scalability = ability to scale — vertical (bigger machine) ya horizontal (more machines).

Q: Container kya hota hai OS level pe? A: Container Linux namespaces (process isolation) aur cgroups (resource limits) use karta hai. Same kernel share karta hai host OS ke saath.

Q: CAP Theorem cloud databases pe kaise apply hota hai? A: Consistency, Availability, Partition Tolerance — teen mein se sirf do guarantee ho sakti hain ek time pe. DynamoDB AP, MongoDB CP, Zookeeper CP choose karta hai.