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Api Object Overview

Prior to the Network Policy API the original NetworkPolicy V1 Resource was the only way for k8s users to apply security rules to their kubernetes workloads. One of the main drawbacks to this API was that it was designed exclusively for use by the Application Developer, although in reality it is used by many different cluster personas, sometimes creating a complex web of objects to be maintained. In Contrast, each resource in the Network Policy API is designed to be used by a specific persona.

With the advent of the AdminNetworkPolicy and BaselineAdminNetworkPolicy resources Cluster Admins will now have the ability to apply policy globally with only a few simple policy objects.

Roles and personas

In this documentation we refer to three primary personas:

  • Application Developer
  • Namespace Administrator
  • Cluster Administrator

Resource Model


Network Policy API resources are in the API group as Custom Resource Definitions (CRDs). Unqualified resource names below will implicitly be in this API group.

Currently, there are two main objects in the Network Policy API resource model:

  • AdminNetworkPolicy (ANP)

  • BaselineAdminNetworkPolicy (BANP)

The diagram below demonstrates how these new API objects interact with each-other and existing NetworkPolicy Objects:

Alt text

General Notes

  • Any well defined AdminNetworkPolicy rules should be read as-is, i.e. there will not be any implicit isolation effects for the Pods selected by the AdminNetworkPolicy, as opposed to what NetworkPolicy rules imply.

  • As of v1alpha1 of this API we focus primarily on E/W cluster traffic and do not address N/S (Ingress/Egress) use cases. However this is an issue the community would like to keep thinking about during further iterations, and a tracking issue can be found/ commented on here ---> issue #28

The AdminNetworkPolicy Resource

The AdminNetworkPolicy (ANP) resource will help administrators set strict security rules for the cluster, i.e. a developer CANNOT override these rules by creating NetworkPolicies that apply to the same workloads as the AdminNetworkPolicy.

AdminNetworkPolicy Actions

Unlike the NetworkPolicy resource in which each rule represents an allowed traffic, AdminNetworkPolicies will enable administrators to set Pass, Deny or Allow as the action of each rule. AdminNetworkPolicy rules should be read as-is, i.e. there will not be any implicit isolation effects for the Pods selected by the AdminNetworkPolicy, as opposed to implicit deny NetworkPolicy rules imply.

  • Pass: Traffic that matches a Pass rule will skip all further rules from all numbered ANPs and instead be enforced by the K8s NetworkPolicies. If there is no K8s NetworkPolicy of BaselineAdminNetworkPolicy rule match traffic will be governed by the implementation. For most implementations, this means "allow", but there may be implementations which have their own policies outside of the standard Kubernetes APIs.
  • Deny: Traffic that matches a Deny rule will be dropped.
  • Allow: Traffic that matches an Allow rule will be allowed.

AdminNetworkPolicy Deny rules are useful for administrators to explicitly block traffic with malicious in-cluster clients, or workloads that pose security risks. Those traffic restrictions can only be lifted once the Deny rules are deleted, modified by the admin, or overridden by a higher priority rule.

On the other hand, the Allow rules can be used to call out traffic in the cluster that needs to be allowed for certain components to work as expected (egress to CoreDNS for example). This traffic should not be blocked when developers apply NetworkPolicy to their Namespaces which isolates the workloads.

AdminNetworkPolicy Pass rules allow an admin to delegate security posture for certain traffic to the Namespace owners by overriding any lower precedence Allow or Deny rules. For example, intra-tenant traffic management can be delegated to tenant admins explicitly with the use of Pass rules. More specifically traffic selected by a Pass rule will skip any further ANP rule selection, be evaluated against any well defined NetworkPolicies, and if not terminated ultimately be evaluated against any BaselineAdminNetworkPolicies.

AdminNetworkPolicy Priorities

Integer priority values were added to the AdminNetworkPolicy API to allow Cluster Admins to express direct and intentional ordering between various ANP Objects.
The Priority field in the ANP spec is defined as an integer value within the range 0 to 1000 where rules with lower priority values have higher precedence. Regardless of priority value all ANPs have higher precedence than any defined NetworkPolicy or BaselineAdminNetworkPolicy objects.

AdminNetworkPolicy Rules

Each ANP should define at least one Ingress or Egress relevant in-cluster traffic flow along with the associated Action that should occur. In each gress rule the user should AT THE MINIMUM define an Action, and at least one AdminNetworkPolicyPeer. Optionally the user may also define select Ports to filter traffic on and also a name for each rule to make management and reporting easier for Admins.

AdminNetworkPolicy Status

For v1alpha1 of this API the ANP status field is simply defined as a list of metav1.conditions. Currently there are no rules as to what these conditions should display, and it is up to each implementation to report what they see fit. For further API iterations the community may consider standardizing these conditions based on the usefulness they provide for various implementors.

The BaselineAdminNetworkPolicy Resource

The BaselineAdminNetworkPolicy (BANP) resource will allow administrators to set baseline security rules that describes default connectivity for cluster workloads, which CAN be overridden by developer NetworkPolicies if needed. The major use case BANPs solve is the ability to flip the default security stance of the cluster.

BaselineAdminNetworkPolicy Rule Actions

BaselineAdminNetworkPolicies allow administrators to define two distinct actions for each well defined rule, Allow and Deny.

  • Deny: Traffic that matches a Deny rule will be dropped.
  • Allow: Traffic that matches an Allow rule will be allowed.

BaselineAdminNetworkPolicy Rules

BANP Rules are defined and behave the same (Except for the Pass action) as ANP rules.

BaselineAdminNetworkPolicy Status

The BANP status field follows the same constructs as used by the AdminNetworkPolicy.Status field.