Why Kubernetes Flat Networks Fail at Scale—and Why Your Cluster Needs a Security Hierarchy

The Limits of Flat Networking Change Gridlock and Compliance Gaps Bringing Order with Tiers and Staged Policies 1. Calico Tiers: Hierarchical Policy Management 2. Staged Network Policies: The Answer to “How Do I Validate?” The Easiest Way To Secure Your Cluster Understanding the Landscape: Core Concepts for Cloud-Native Security Resources for Further Learning Kubernetes networking offers incredible power, but scaling that power often transforms a clean architecture into a tangled web of complexity. Managing traffic flow between hundreds of microservices across dozens of namespaces presents a challenge that touches every layer of the organization, from engineers debugging connections to the architects designing for compliance. The solution to these diverging challenges lies in bringing structure and validation to standard Kubernetes networking. Here is a look at how Calico Tiers and Staged Network Policies help you get rid of this networking chaos. The default Kubernetes NetworkPolicy resource operates in a flat hierarchy. In a small cluster, this is manageable. However, in an enterprise environment with multiple tenants, teams, and compliance requirements, “flat” quickly becomes unmanageable, and dangerous. To make this easier, imagine a large office building where every single employee has a key that opens every door. To secure the CEO’s office in a flat network, you have to put “Do Not Enter” signs on every door that could lead to it. That is flat networking, secure by exclusion rather than inclusion.