Load Balancing & Failover Strategies

SecureCart’s e-commerce platform must handle fluctuating traffic, prevent downtime, and maintain seamless customer experiences. AWS provides load balancing and failover strategies to ensure scalability, fault tolerance, and high availability (HA).

✔ Why does SecureCart use Load Balancing & Failover Strategies?

• Distributes traffic efficiently across multiple compute resources.

• Prevents a single point of failure by routing requests to healthy instances.

• Ensures automatic recovery from failed components.

• Improves performance by dynamically scaling resources.

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🔹 Step 1: Understanding Load Balancing in AWS

✔ What is Load Balancing?

• Distributes incoming traffic across multiple servers or compute resources.

• Ensures applications remain available even if individual instances fail.

• Automatically scales based on demand to handle traffic spikes.

✔ AWS Load Balancing Types:

Load Balancer Type	Purpose	SecureCart Use Case
Application Load Balancer (ALB)	Distributes HTTP/HTTPS traffic and supports advanced routing features.	Routes API requests based on paths (e.g., /checkout to checkout service, /products to product catalog service).
Network Load Balancer (NLB)	Handles TCP/UDP traffic with ultra-low latency.	Manages secure payment transactions that require fast, reliable connections.
Gateway Load Balancer (GWLB)	Routes traffic to third-party security appliances.	Filters traffic through a web application firewall (WAF) before reaching SecureCart’s services.
Classic Load Balancer (CLB)	Legacy load balancer supporting both HTTP & TCP traffic.	Not recommended; SecureCart uses ALB/NLB for modern architectures.

✅ Best Practices: ✔ Use ALB for web applications that require advanced routing. ✔ Deploy NLB for high-performance TCP-based workloads. ✔ Configure health checks to detect unhealthy instances automatically.

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🔹 Step 2: Designing SecureCart’s Load Balancing Strategy

✔ Why? – SecureCart ensures consistent performance by distributing traffic efficiently.

AWS Load Balancing Feature	Purpose	SecureCart Implementation
Path-Based Routing	Routes traffic based on the URL path.	ALB routes /cart requests to the cart service and /orders to the order processing service.
Host-Based Routing	Directs traffic based on domain name.	shop.securecart.com → storefront, admin.securecart.com → admin panel.
Sticky Sessions	Ensures a user session stays on the same backend instance.	Used for maintaining session state in the checkout service.
Cross-Zone Load Balancing	Distributes traffic evenly across Availability Zones (AZs).	Enabled to balance load across multiple regions.

✅ Best Practices: ✔ Enable cross-zone load balancing to evenly distribute requests. ✔ Use path-based routing to separate API endpoints efficiently. ✔ Leverage sticky sessions for stateful applications (only when necessary).

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🔹 Step 3: Implementing Failover Strategies for High Availability

✔ Why? – SecureCart prepares for failures by implementing automatic failover strategies.

Failover Strategy	Purpose	SecureCart Use Case
Route 53 Failover Routing	Automatically redirects traffic to a healthy region.	If us-east-1 fails, users are redirected to us-west-2.
Multi-AZ Deployment	Runs workloads across multiple AZs for resilience.	Database and backend services are distributed across at least 2 AZs.
Multi-Region Active-Passive	Keeps a secondary region as a hot standby.	Orders are processed in the main region, but an alternate region is always ready.
Active-Active Multi-Region	Distributes traffic between multiple active regions.	Users are dynamically routed to the nearest available region.

✅ Best Practices: ✔ Use Route 53 failover routing to redirect traffic when a region goes down. ✔ Deploy critical workloads in Multi-AZ for fault tolerance. ✔ Choose Active-Passive or Active-Active architecture based on business needs.

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🔹 Step 4: Auto Scaling for Load Balancer Resilience

✔ Why? – SecureCart uses AWS Auto Scaling to dynamically adjust resources.

Auto Scaling Component	Purpose	SecureCart Implementation
EC2 Auto Scaling	Automatically adds/removes EC2 instances based on demand.	Scales up checkout service when there’s a surge in traffic.
Application Auto Scaling	Adjusts ECS, Lambda, and DynamoDB throughput dynamically.	Ensures database read/write capacity increases during peak hours.
Target Tracking Scaling	Maintains optimal CPU/memory utilization.	Keeps API servers at 60% CPU load for cost-efficiency.
Scheduled Scaling	Increases resources at expected traffic peaks.	Scales EC2 instances every day at 6 PM before rush hours.

✅ Best Practices: ✔ Use EC2 Auto Scaling with ALB to handle traffic spikes. ✔ Leverage target tracking to maintain performance without overprovisioning. ✔ Enable scheduled scaling for predictable workloads.

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🔹 Step 5: Monitoring & Security for Load Balancing & Failover

✔ Why? – SecureCart monitors system health and secures load balancer traffic.

AWS Monitoring Tool	Purpose	SecureCart Use Case
Amazon CloudWatch	Tracks load balancer health and performance.	Monitors request latency to detect bottlenecks.
AWS WAF	Protects ALB from DDoS and malicious attacks.	Blocks SQL injection and bot traffic at the load balancer level.
AWS Shield	Mitigates large-scale DDoS attacks.	Prevents volumetric attacks from taking down SecureCart APIs.
AWS X-Ray	Traces requests to identify performance bottlenecks.	Detects slow database queries affecting checkout performance.

✅ Best Practices: ✔ Monitor load balancer metrics in CloudWatch to detect failures early. ✔ Use AWS WAF to block unauthorized traffic. ✔ Enable AWS Shield Advanced for DDoS protection on critical services.

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🚀 Summary

✔ Use ALB for web applications, NLB for high-performance networking. ✔ Distribute application workloads across multiple AZs for high availability. ✔ Implement Route 53 failover to reroute traffic in case of regional failures. ✔ Use EC2 Auto Scaling and Application Auto Scaling to manage demand. ✔ Monitor, secure, and optimize performance using CloudWatch, WAF, and AWS Shield.

Scenario:

SecureCart needs to handle traffic spikes and implement automated failover to ensure that e-commerce transactions are never disrupted.

Key Learning Objectives:

✅ Use Application Load Balancer (ALB) vs. Network Load Balancer (NLB) ✅ Implement Route 53 Failover Routing ✅ Understand Amazon RDS Proxy for database connection pooling

Hands-on Labs:

1️⃣ Set Up an ALB for SecureCart’s Frontend Services 2️⃣ Use Route 53 Failover Routing to Redirect Traffic During Outages 3️⃣ Implement Amazon RDS Proxy to Improve Database Availability

🔹 Outcome: SecureCart eliminates single points of failure using load balancing and failover techniques.