networkpolicy: default-deny + sirf zaroori raasta

manifests/demo-app/networkpolicy.yaml

@@ -0,0 +1,36 @@
+# Pehle sab band. Pod compromise ho to wo cluster me idhar-udhar na ja sake.
+apiVersion: networking.k8s.io/v1
+kind: NetworkPolicy
+metadata:
+  name: default-deny-all
+  namespace: demo-app
+spec:
+  podSelector: {}
+  policyTypes: [Ingress, Egress]
+---
+# Ab sirf jo chahiye wahi khola: app port par traffic andar, DNS bahar.
+apiVersion: networking.k8s.io/v1
+kind: NetworkPolicy
+metadata:
+  name: allow-app
+  namespace: demo-app
+spec:
+  podSelector:
+    matchLabels:
+      app: demo-app
+  policyTypes: [Ingress, Egress]
+  ingress:
+    - ports:
+        - protocol: TCP
+          port: 8000
+  egress:
+    # DNS ke bina kuch bhi kaam nahi karega
+    - to:
+        - namespaceSelector:
+            matchLabels:
+              kubernetes.io/metadata.name: kube-system
+      ports:
+        - protocol: UDP
+          port: 53
+        - protocol: TCP
+          port: 53

manifests/hello-api/networkpolicy.yaml

@@ -0,0 +1,36 @@
+# Pehle sab band. Pod compromise ho to wo cluster me idhar-udhar na ja sake.
+apiVersion: networking.k8s.io/v1
+kind: NetworkPolicy
+metadata:
+  name: default-deny-all
+  namespace: hello-api
+spec:
+  podSelector: {}
+  policyTypes: [Ingress, Egress]
+---
+# Ab sirf jo chahiye wahi khola: app port par traffic andar, DNS bahar.
+apiVersion: networking.k8s.io/v1
+kind: NetworkPolicy
+metadata:
+  name: allow-app
+  namespace: hello-api
+spec:
+  podSelector:
+    matchLabels:
+      app: hello-api
+  policyTypes: [Ingress, Egress]
+  ingress:
+    - ports:
+        - protocol: TCP
+          port: 8000
+  egress:
+    # DNS ke bina kuch bhi kaam nahi karega
+    - to:
+        - namespaceSelector:
+            matchLabels:
+              kubernetes.io/metadata.name: kube-system
+      ports:
+        - protocol: UDP
+          port: 53
+        - protocol: TCP
+          port: 53