[Solved] You wrote this NetworkPolicy but pods labeled role=frontend still cannot access app=nginx pods on port 80. What is wrong? apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name:... | Kubernetes

Kubernetes - RBAC and Security

You wrote this NetworkPolicy but pods labeled role=frontend still cannot access app=nginx pods on port 80. What is wrong?

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: allow-nginx
spec:
  podSelector:
    matchLabels:
      app: nginx
  ingress:
  - from:
    - podSelector:
        matchLabels:
          role: frontend
    ports:
    - protocol: TCP
      port: 8080

AThe metadata name is incorrect

BThe podSelector is missing in the policy

CThe port in the policy is 8080 but nginx listens on port 80

DThe protocol TCP is not supported in NetworkPolicy

Step-by-Step Solution

Solution:

Step 1: Compare port in policy with actual service port
The policy allows ingress on TCP port 8080, but nginx usually listens on port 80.
Step 2: Identify mismatch causing blocked traffic
Because the port does not match nginx's listening port, traffic is blocked despite correct podSelector.
Final Answer:
The port in the policy is 8080 but nginx listens on port 80 -> Option C
Quick Check:
Port mismatch blocks traffic = D [OK]

Quick Trick: Check port numbers match service and policy exactly [OK]

Common Mistakes:

Ignoring port mismatch
Assuming protocol TCP is unsupported
Thinking metadata name affects traffic

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You wrote this NetworkPolicy but pods labeled role=frontend still cannot access app=nginx pods on port 80. What is wrong?

Step 1: Compare port in policy with actual service port

Step 2: Identify mismatch causing blocked traffic

Final Answer:

Quick Check:

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