I have two namespaces: prod and default. I want to disable access for resources inside these namespaces (resources from default NS can't get access for resources from prod, and resources from prod can't get access for resources from default) BUT allow the opportunity to access these resources for external traffic (ingresses).

# namespaces.yaml

---
kind: Namespace
apiVersion: v1
metadata:
  name: prod
  labels:
    tier: prod

---
kind: Namespace
apiVersion: v1
metadata:
  name: default
  labels:
    tier: infra

# network-policies.yaml

---
kind: NetworkPolicy
apiVersion: networking.k8s.io/v1
metadata:
  name: network
  namespace: prod
spec:
  podSelector: {}
  ingress:
    - from:
      - podSelector: {}
---
kind: NetworkPolicy
apiVersion: networking.k8s.io/v1
metadata:
  name: network
  namespace: default
spec:
  podSelector: {}
  ingress:
    - from:
      - namespaceSelector:
          matchLabels:
            tier: dev
      - namespaceSelector:
          matchLabels:
            tier: rc

# services.yaml

---
apiVersion: v1
kind: Service
metadata:
  name: {{ include "conference.appService" . }}
  labels:
    app: {{ include "conference.name" . }}
    release: {{ .Release.Name }}
spec:
  type: NodePort
  ports:
    - name: http
      port: 80
      targetPort: http
      protocol: TCP
  selector:
    app: {{ include "conference.name" . }}
    release: {{ .Release.Name }}
    role: app

Pods from prod have access to the other pods inside given namespace. Pods from default don't have access to the pods inside prod.

When I try to get access to the service from the browser it's blocked. When I try to use port-forwarding to the service inside prod - all works fine.