Amazon EKS — Load Balancing — Practice Exercises

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Chapter 10 — Practice Exercises

Exercise 1: ALB vs NLB

Question: You have 3 services: HTTP REST API, gRPC service, and a WebSocket chat app. Which load balancer type would you use for each and why?

Show Solution
Service LB Type Why
HTTP REST API ALB Layer 7, path routing, SSL termination
gRPC service NLB gRPC uses HTTP/2 over TCP; NLB preserves connection
WebSocket chat ALB ALB supports WebSocket natively with sticky sessions

Note: ALB also supports gRPC (since 2020), so ALB could work for all three. NLB is preferred for gRPC when you need static IPs or ultra-low latency.

Exercise 2: HTTPS Ingress

Question: Write a complete Ingress resource that: serves app.example.com on HTTPS, redirects HTTP to HTTPS, uses an ACM certificate, targets pods directly (ip mode), and shares an ALB with other services.

Show Solution 
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: app-ingress
  annotations:
    kubernetes.io/ingress.class: alb
    alb.ingress.kubernetes.io/scheme: internet-facing
    alb.ingress.kubernetes.io/target-type: ip
    alb.ingress.kubernetes.io/certificate-arn: arn:aws:acm:us-east-1:123456789012:certificate/abc-123
    alb.ingress.kubernetes.io/listen-ports: '[{"HTTP":80},{"HTTPS":443}]'
    alb.ingress.kubernetes.io/ssl-redirect: "443"
    alb.ingress.kubernetes.io/group.name: shared-alb
spec:
  rules:
    - host: app.example.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: app-service
                port:
                  number: 80

Exercise 3: Multi-Service Routing

Question: Design an Ingress that routes: example.com/ → frontend, example.com/api/v1 → api-v1, example.com/api/v2 → api-v2, admin.example.com → admin panel.

Show Solution 
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: multi-service
  annotations:
    kubernetes.io/ingress.class: alb
    alb.ingress.kubernetes.io/scheme: internet-facing
    alb.ingress.kubernetes.io/target-type: ip
spec:
  rules:
    - host: example.com
      http:
        paths:
          - path: /api/v2
            pathType: Prefix
            backend:
              service:
                name: api-v2
                port:
                  number: 80
          - path: /api/v1
            pathType: Prefix
            backend:
              service:
                name: api-v1
                port:
                  number: 80
          - path: /
            pathType: Prefix
            backend:
              service:
                name: frontend
                port:
                  number: 80
    - host: admin.example.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: admin
                port:
                  number: 80

Order matters: /api/v2 and /api/v1 must come before / to avoid the catch-all matching first.

Exercise 4: Troubleshoot ALB

Question: You created an Ingress but no ALB is being provisioned. kubectl get ingress shows no ADDRESS. List 5 things to check.

Show Solution 
# 1. Check LB controller is running
$ kubectl get pods -n kube-system -l app.kubernetes.io/name=aws-load-balancer-controller

# 2. Check controller logs
$ kubectl logs -n kube-system -l app.kubernetes.io/name=aws-load-balancer-controller

# 3. Check Ingress events
$ kubectl describe ingress <name>
# Look for events like "Failed to create ALB"

# 4. Check subnet tags
$ aws ec2 describe-subnets --filters "Name=tag-key,Values=kubernetes.io/role/elb"
# Public subnets need: kubernetes.io/role/elb = 1

# 5. Check IRSA permissions
$ kubectl describe sa aws-load-balancer-controller -n kube-system
# Should have eks.amazonaws.com/role-arn annotation

Exercise 5: Cost Optimization

Question: You have 10 microservices, each with its own Ingress creating a separate ALB. At $18/month per ALB, that’s $180/month. How do you reduce this?

Show Solution

Use Ingress groups to share a single ALB:

# Service 1
annotations:
  alb.ingress.kubernetes.io/group.name: shared-alb
  alb.ingress.kubernetes.io/group.order: "1"

# Service 2
annotations:
  alb.ingress.kubernetes.io/group.name: shared-alb
  alb.ingress.kubernetes.io/group.order: "2"

# ... repeat for all 10 services

Result:

  • Before: 10 ALBs × $18 = $180/month
  • After: 1 ALB × $18 = $18/month
  • Savings: $162/month (90%)

You pay slightly more in LCU (load capacity units) since one ALB handles all traffic, but it’s still far cheaper than 10 ALBs.

What’s Next?

Automatic scaling: Chapter 11 — Auto Scaling.

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