第 9 章 Network policy

Deny all traffic:

To make a project deny by default, add a NetworkPolicy object that matches all pods but accepts no traffic:

kind: NetworkPolicy
apiVersion: networking.k8s.io/v1
metadata:
  name: deny-by-default
spec:
  podSelector:
  ingress: []

Only allow connections from the OpenShift Container Platform Ingress Controller:

To make a project allow only connections from the OpenShift Container Platform Ingress Controller, add the following NetworkPolicy object.

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: allow-from-openshift-ingress
spec:
  ingress:
  - from:
    - namespaceSelector:
        matchLabels:
          network.openshift.io/policy-group: ingress
  podSelector: {}
  policyTypes:
  - Ingress

If the Ingress Controller is configured with endpointPublishingStrategy: HostNetwork, then the Ingress Controller pod runs on the host network. When running on the host network, the traffic from the Ingress Controller is assigned the netid:0 Virtual Network ID (VNID). The netid for the namespace that is associated with the Ingress Operator is different, so the matchLabel in the allow-from-openshift-ingress network policy does not match traffic from the default Ingress Controller. With OpenShift SDN, the default namespace is assigned the netid:0 VNID and you can allow traffic from the default Ingress Controller by labeling your default namespace with network.openshift.io/policy-group: ingress.

Only accept connections from pods within a project:

To make pods accept connections from other pods in the same project, but reject all other connections from pods in other projects, add the following NetworkPolicy object:

kind: NetworkPolicy
apiVersion: networking.k8s.io/v1
metadata:
  name: allow-same-namespace
spec:
  podSelector:
  ingress:
  - from:
    - podSelector: {}

Only allow HTTP and HTTPS traffic based on pod labels:

To enable only HTTP and HTTPS access to the pods with a specific label (role=frontend in following example), add a NetworkPolicy object similar to the following:

kind: NetworkPolicy
apiVersion: networking.k8s.io/v1
metadata:
  name: allow-http-and-https
spec:
  podSelector:
    matchLabels:
      role: frontend
  ingress:
  - ports:
    - protocol: TCP
      port: 80
    - protocol: TCP
      port: 443

Accept connections by using both namespace and pod selectors:

To match network traffic by combining namespace and pod selectors, you can use a NetworkPolicy object similar to the following:

kind: NetworkPolicy
apiVersion: networking.k8s.io/v1
metadata:
  name: allow-pod-and-namespace-both
spec:
  podSelector:
    matchLabels:
      name: test-pods
  ingress:
    - from:
      - namespaceSelector:
          matchLabels:
            project: project_name
        podSelector:
          matchLabels:
            name: test-pods

Reduce the number of OVS flow rules by using namespaces to contain groups of pods that need to be isolated.

NetworkPolicy objects that select a whole namespace, by using the namespaceSelector or an empty podSelector, generate only a single OVS flow rule that matches the VXLAN virtual network ID (VNID) of the namespace.