Reuqest Flow

How a Request Flows in Your AWS EKS Setup

Since you have: ✅ EKS cluster with workloads deployed ✅ Cloudflare for DNS management ✅ Ingress with AWS ALB Ingress Controller ✅ Deployment with 3 replicas ✅ Karpenter for auto-scaling

Here’s a step-by-step breakdown of how a request flows when a user accesses your application via a domain (e.g., https://example.com):

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1️⃣ User Request via Domain Name

• A user enters https://example.com in a browser.

• Cloudflare (acting as a DNS provider) resolves example.com to an AWS ALB's public IP.

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2️⃣ Cloudflare Resolves and Routes to AWS ALB

• If you use Cloudflare Proxy Mode (Orange Cloud ☁️), Cloudflare acts as a reverse proxy.

• If DNS-only Mode (Gray Cloud), Cloudflare just resolves the domain to AWS ALB’s DNS.

• The request is forwarded to the AWS Application Load Balancer (ALB).

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3️⃣ AWS ALB Evaluates and Routes to Kubernetes Ingress

• ALB listens on HTTP/HTTPS (80/443) and forwards the request based on configured Ingress rules.

• The AWS ALB Ingress Controller is responsible for:

  • Mapping the incoming request to the correct Kubernetes Service.

  • Enforcing TLS termination if configured.

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4️⃣ Ingress Sends Request to Service

• The Ingress resource in EKS forwards the request to the respective Kubernetes Service (e.g., example-service).

• The Service (likely a ClusterIP or NodePort) directs traffic to one of the three pods.

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5️⃣ Service Routes to One of the 3 Pods

• The Kubernetes Service (LoadBalancer/ClusterIP) distributes traffic across 3 replicas of the pod.

• Kubernetes kube-proxy or CNI (e.g., AWS VPC CNI) ensures load balancing between pods.

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6️⃣ Pod Handles the Request

• The pod (running your application) processes the request.

• It may interact with a database (e.g., RDS, DynamoDB) or external APIs.

• The response is generated and sent back to the Service → ALB → Cloudflare → User.

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7️⃣ Karpenter Scales Up if Needed

• If traffic increases beyond what the 3 pods can handle:

  • HPA (Horizontal Pod Autoscaler) scales pods up (e.g., from 3 to 6 pods).

  • If no sufficient worker nodes exist, Karpenter provisions a new EC2 node dynamically.

  • The new node joins the EKS cluster, and additional pods are scheduled.

• Karpenter ensures efficient utilization of nodes by optimizing instance types and sizes.

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Flow Summary:

1️⃣ User → Cloudflare (DNS Proxy) → AWS ALB (Ingress Controller) → Ingress → Kubernetes Service 2️⃣ Service → One of the Pods → Application Handles Request → Response Sent Back 3️⃣ Karpenter scales EC2 nodes when pod demand increases

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Example Architecture Diagram

User (Browser) --> Cloudflare DNS
                      |
                      v
                 AWS ALB (Ingress Controller)
                      |
                      v
              Kubernetes Ingress
                      |
                      v
            Kubernetes Service (ClusterIP)
          /       |        \
    Pod 1    Pod 2    Pod 3 (Application)
                      |
                      v
                 Database/API Call

    Karpenter scales nodes when traffic spikes

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Potential Issues and Fixes

Issue	Cause	Fix
404 Not Found	Incorrect Ingress rules	Check Ingress host and ALB settings
503 Service Unavailable	No healthy pods	Ensure pods are running (kubectl get pods)
SSL Handshake Error	Cloudflare <> ALB mismatch	Match SSL settings between Cloudflare and ALB
High Latency	Insufficient pod resources	Optimize pod CPU/memory requests
Pods Stuck in Pending	No available nodes	Check if Karpenter is provisioning new nodes

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Final Thoughts

• Your setup efficiently handles requests with Cloudflare, ALB, Kubernetes Ingress, and Karpenter.

• Karpenter ensures cost-efficient, on-demand scaling of worker nodes.

• Using HPA + Karpenter gives pod scaling + node auto-provisioning, ensuring seamless performance.

Would you like Terraform or YAML configurations to automate this setup? 🚀