A/B testing with Ingress in Kubernetes - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding A/B Testing with Kubernetes Ingress

What is the primary purpose of using Kubernetes Ingress for A/B testing?

A To automatically scale backend pods based on traffic load

B To encrypt all traffic between clients and backend services

C To route a percentage of traffic to different backend services for comparison

D To store user session data for backend services

💡 Hint

Think about how traffic can be split to test different versions of an application.

Kubernetes Ingress can be configured to route traffic to different backend services based on rules, enabling A/B testing by sending a portion of users to different versions.

❓ Configuration

intermediate

Configuring Traffic Split in Ingress for A/B Testing

Given the following Ingress snippet, what percentage of traffic is routed to service-v2?

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: ab-test-ingress
spec:
  rules:
  - http:
      paths:
      - path: /app
        pathType: Prefix
        backend:
          service:
            name: service-v1
            port:
              number: 80
      - path: /app
        pathType: Prefix
        backend:
          service:
            name: service-v2
            port:
              number: 80
  traffic:
    - serviceName: service-v1
      weight: 80
    - serviceName: service-v2
      weight: 20

A 0%

B 80%

C 50%

D 20%

💡 Hint

Look at the weight values assigned to each service.

The weight field defines the percentage of traffic routed to each service. Here, service-v2 has weight 20, meaning 20% of traffic.

💻 Command Output

advanced

Output of kubectl describe Ingress with A/B Testing Annotations

What output will you see when running kubectl describe ingress ab-test-ingress if the Ingress has the annotation nginx.ingress.kubernetes.io/canary: "true" on service-v2 path?

Kubernetes

kubectl describe ingress ab-test-ingress

A

Annotations:
  nginx.ingress.kubernetes.io/canary: "true"
Rules:
  Host: <none>
  Paths:
    /app -> service-v1:80
    /app -> service-v2:80 (canary)

B Error from server (NotFound): ingress "ab-test-ingress" not found

C

No annotations found
Rules:
  /app -> service-v1:80
  /app -> service-v2:80

D

Annotations:
  nginx.ingress.kubernetes.io/canary: "false"
Rules:
  /app -> service-v1:80

💡 Hint

Canary annotation marks the service as a canary deployment in the Ingress description.

The annotation nginx.ingress.kubernetes.io/canary: "true" marks the backend as canary, which is shown in the describe output next to the service path.

❓ Troubleshoot

advanced

Troubleshooting Traffic Not Splitting in A/B Testing

You configured an Ingress with two services for A/B testing, but all traffic goes to service-v1 only. What is the most likely cause?

A The services have different port numbers configured

B The Ingress controller does not support traffic splitting by weight

C The Ingress resource is missing the <code>spec.rules</code> section

D The backend pods are not labeled with <code>app=service-v2</code>

💡 Hint

Not all Ingress controllers support weighted traffic splitting.

Weighted traffic splitting is a feature supported by some Ingress controllers like NGINX with canary annotations or specific configurations. If the controller does not support it, traffic will not split.

🔀 Workflow

expert

Steps to Implement A/B Testing with Kubernetes Ingress

What is the correct order of steps to implement A/B testing using Kubernetes Ingress?

A 1,2,3,4

B 2,1,4,3

C 1,3,2,4

D 3,1,2,4

💡 Hint

Think about deploying first, then configuring routing, then monitoring, then adjusting.

The correct workflow is to first deploy both versions, then configure Ingress to split traffic, monitor results, and finally adjust traffic weights accordingly.