Load Balancing for Scalability & High Availability

Load balancing is a critical component of scalable and highly available architectures in AWS. It ensures that incoming traffic is evenly distributed across multiple resources, preventing overloading and ensuring reliable performance. SecureCart requires an effective load balancing strategy to handle high traffic demand, prevent service outages, and optimize resource utilization.

✔ Why does SecureCart need Load Balancing?

• Ensures High Availability by distributing traffic across multiple instances.

• Improves Performance by reducing latency and ensuring fast response times.

• Enables Scalability by automatically adding/removing instances based on demand.

• Enhances Security by protecting backend services from direct exposure to the internet.

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🔹 Step 1: Understanding AWS Load Balancer Types

✔ AWS offers different load balancers for specific use cases:

Load Balancer Type	Purpose	SecureCart Implementation
Application Load Balancer (ALB)	Layer 7 load balancing for HTTP/HTTPS traffic.	Handles SecureCart’s web and API traffic across multiple ECS Fargate instances.
Network Load Balancer (NLB)	Layer 4 (TCP/UDP) load balancing for low-latency connections.	Optimizes SecureCart’s payment processing services requiring high-speed connections.
Gateway Load Balancer (GWLB)	Distributes traffic to third-party network appliances.	Manages SecureCart’s security and intrusion detection systems.
Classic Load Balancer (CLB)	Legacy load balancing across EC2 instances.	Not recommended for new applications; SecureCart uses ALB and NLB instead.

✅ Best Practices: ✔ Use ALB for web applications and HTTP-based APIs. ✔ Use NLB for high-performance, low-latency workloads. ✔ Implement GWLB for security-focused network traffic management.

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🔹 Step 2: Configuring Load Balancing for High Availability

✔ How SecureCart ensures high availability using Load Balancers:

Feature	Purpose	SecureCart Use Case
Multi-AZ Deployment	Ensures redundancy by distributing traffic across multiple AZs.	Prevents single point of failure for SecureCart’s e-commerce platform.
Health Checks	Detects and removes unhealthy instances.	Ensures SecureCart customers are only routed to healthy ECS tasks.
Failover Mechanisms	Redirects traffic to available instances in case of failure.	Keeps SecureCart online even if one AZ goes down.

✅ Best Practices: ✔ Deploy ALB and NLB across multiple Availability Zones. ✔ Enable active health checks for real-time monitoring of backend instances. ✔ Configure Route 53 failover routing to ensure seamless disaster recovery.

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🔹 Step 3: Implementing Auto Scaling with Load Balancing

✔ How SecureCart dynamically scales its infrastructure:

Auto Scaling Feature	Purpose	SecureCart Use Case
Application Auto Scaling	Adjusts ECS task count based on traffic.	Automatically scales SecureCart’s checkout service during flash sales.
EC2 Auto Scaling	Dynamically adds/removes EC2 instances.	Ensures SecureCart’s order processing system scales with demand.
Target Tracking Policies	Automatically scales resources based on metrics.	Increases ECS task count when CPU utilization exceeds 70%.

✅ Best Practices: ✔ Use ALB with Auto Scaling groups for web applications. ✔ Configure Auto Scaling policies based on CPU, memory, and request rates. ✔ Enable predictive scaling for anticipated traffic spikes.

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🔹 Step 4: Load Balancer Security & Access Control

✔ How SecureCart secures load balancing traffic:

Security Measure	Purpose	SecureCart Implementation
TLS Termination	Encrypts incoming connections using HTTPS.	ALB terminates TLS at the load balancer level, ensuring secure checkout sessions.
AWS WAF (Web Application Firewall)	Protects against DDoS, SQL injection, and XSS attacks.	Blocks malicious requests targeting SecureCart’s APIs.
Restricting Public Access	Ensures only authorized traffic reaches the backend.	Uses Security Groups & IAM policies to limit ALB access.

✅ Best Practices: ✔ Use AWS Certificate Manager (ACM) to manage TLS certificates for ALB. ✔ Deploy AWS WAF to protect APIs and web applications from threats. ✔ Restrict ALB/NLB access using IAM and Security Groups.

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🔹 Step 5: Optimizing Load Balancer Performance

✔ How SecureCart optimizes performance using Load Balancers:

Optimization Feature	Purpose	SecureCart Use Case
Content-Based Routing	Routes traffic based on URL paths or hostnames.	SecureCart directs checkout requests to a dedicated backend.
Sticky Sessions	Ensures requests from the same user are routed to the same instance.	Enhances user experience for SecureCart’s session-based application.
Cross-Zone Load Balancing	Distributes traffic evenly across AZs.	Improves utilization across SecureCart’s instances.

✅ Best Practices: ✔ Use path-based routing to segment traffic efficiently. ✔ Enable sticky sessions for stateful applications. ✔ Use cross-zone load balancing to optimize resource usage.

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🔹 Step 6: Monitoring & Troubleshooting Load Balancer Traffic

✔ How SecureCart monitors and optimizes its Load Balancers:

Monitoring Tool	Purpose	SecureCart Use Case
Amazon CloudWatch	Monitors ALB/NLB performance and traffic metrics.	Tracks SecureCart’s API request rate and response times.
AWS X-Ray	Traces HTTP requests for latency analysis.	Identifies slow requests in SecureCart’s checkout process.
ELB Access Logs	Provides detailed request logs for debugging.	Helps SecureCart investigate failed checkout transactions.

✅ Best Practices: ✔ Set CloudWatch alarms for latency and error rate spikes. ✔ Use X-Ray tracing to analyze slow-performing requests. ✔ Enable ELB Access Logs for detailed traffic analysis.

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🚀 Summary

✔ Use ALB for HTTP/HTTPS traffic, NLB for low-latency TCP connections, and GWLB for security appliances. ✔ Deploy Load Balancers across multiple AZs for high availability. ✔ Enable Auto Scaling to dynamically adjust resources based on demand. ✔ Secure Load Balancers with TLS termination, WAF, and IAM-based access restrictions. ✔ Optimize performance with path-based routing, sticky sessions, and cross-zone balancing. ✔ Monitor Load Balancer performance using CloudWatch, X-Ray, and ELB Access Logs.

Scenario:

SecureCart must scale workloads dynamically while ensuring high availability and reliability.

Key Learning Objectives:

✅ Understand Application Load Balancer (ALB) vs. Network Load Balancer (NLB) ✅ Implement target groups and listener rules for traffic distribution ✅ Use cross-zone load balancing for high availability

Hands-on Labs:

1️⃣ Set Up an ALB for SecureCart’s Web Tier 2️⃣ Deploy an NLB for Low-Latency & High-Throughput Applications 3️⃣ Configure Load Balancer Stickiness & Target Groups for Efficient Scaling

🔹 Outcome: SecureCart ensures scalable and resilient application traffic distribution.