Kubernetes Network Policies in OpenShift

The cause wasn’t code. It was the network.

Kubernetes Network Policies in OpenShift decide which pods talk to which, and how. Without them, every pod can reach every other pod. In production, that’s a risk and a liability. Network Policies let you lock down communication, isolate workloads, and meet compliance rules.

In OpenShift, Network Policies follow the same Kubernetes API spec, but the platform layers on its own features and operational model. Policies are namespaced. They match pods by labels. Ingress rules control incoming traffic; egress rules control outgoing traffic. You can mix both, in one policy, to define exactly what traffic is allowed.

A new policy with no rules will drop all traffic for matching pods. To open access, you must specify from or to selectors in your rules. OpenShift uses its default SDN plugin or OVN-Kubernetes to enforce these rules at the network layer. Testing policies should happen in dev or staging first, because a single misapplied label can block entire app tiers.

Best practices:

• Start with deny-all policies, then allow only what’s required.
• Group pods with precise labels so rules target only what they should.
• Keep policies version-controlled and peer-reviewed.
• Use oc commands or the OpenShift Console for quick inspection and debugging.

Applying Kubernetes Network Policies in OpenShift isn’t optional for secure clusters. They reduce the blast radius of a compromise, shield sensitive services, and prevent noisy neighbors from interfering.

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