Kubernetes CKA sample exam question 97 with answer

Question
Create a NetworkPolicy in the prod namespace which will allow traffic from ALL pods labelled as tier=frontend running in ALL namespaces.

Answer
This is a tricky question- to select pods with label tier=frontend from ALL namespaces.
So, you have to add podSelector configuration along with namespaceSelector block.
If you specify podSelector as a separate block then all pods will be selected only from default namespace with specific label.
Generate netpol:

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: allow-all-ns
  namespace: prod
spec:
  podSelector: {}
  policyTypes:
  - Ingress
  ingress:
  - from:
    - namespaceSelector: {}
      podSelector:
        matchLabels:
	  tier: frontend

Apply and test:

kubectl apply -f np.yaml
kubectl -n prod describe netpol allow-all-ns