Kubernetes Network Policies Onboarding: Map, Isolate, Allow, Validate, Repeat

The pods were talking to each other, and no one knew who they were talking to. The cluster was open. The network was wide. The risk was real.

Kubernetes network policies are the firewall for the cluster’s internal traffic. They define which pods can connect, on which ports, and in which direction. Without them, every pod can reach every other pod. That’s default allow. Security depends on moving to default deny, and granting access only where needed.

The onboarding process for Kubernetes network policies starts with mapping the flows. List your services. Identify which pods need to talk to which. Document the namespace boundaries. This forms the baseline.

Next, create a test namespace. Here, define a simple policy that denies all inbound and outbound traffic. Apply it. Confirm that pods are now isolated. This proves the policy works.

From isolation, add rules. Allow specific ingress from trusted namespaces. Permit egress to required external services. Use labels to target pods precisely. Avoid wildcards. Keep rules short and readable.

Validate in staging before going to production. Use kubectl to inspect active policies. Run automated tests to confirm connections succeed or fail as expected. Audit logs to catch unexpected flows.

Repeat the process for each namespace. Keep policies under version control. Update them alongside application changes. Never allow “temporary” rules without a removal plan.

Kubernetes network policies onboarding is not a one-time task. It is a cycle: map, isolate, allow, validate, repeat. Strong network boundaries keep clusters safe from internal and external threats.

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