Three Tools to Test Kubernetes NetworkPolicies Before They Break Production

Kubernetes NetworkPolicies are commonly merged without validation, leading to silent misconfigurations that only surface when a pod loses access to a critical dependency mid-deployment. Common pitfalls include implicit default-deny behavior, undetected label typos that render policies ineffective, and unpredictable combined effects when multiple teams own overlapping policies in the same namespace. The kubectl-np-viewer plugin addresses this by computing and displaying the resolved ingress and egress rules across all policies in a namespace, replacing manual YAML tracing. The netpol-analyzer tool from the np-guard project enables static analysis and CI integration, offering features like policy diffing, dead-rule detection, and connectivity mapping to catch breaking changes before merge. Together with a CI pipeline setup, these tools shift NetworkPolicy validation left, catching misconfigurations at the pull request stage rather than during a production incident.