Enable audit log collection for RKE2

Views:

Enable Kubernetes audit log collection on a RKE2 cluster by creating the audit policy and webhook configuration files, configuring RKE2 to use them, and restarting the service.

Important

RKE2 runs kube-apiserver as a container, so the audit directory must be mounted into the container.

Procedure

Create the audit configuration directory and files.

Run the following commands to create the audit policy and webhook configuration:

sudo mkdir -p /var/lib/rancher/rke2/server/audit

sudo tee /var/lib/rancher/rke2/server/audit/audit-policy.yaml << 'EOF'
apiVersion: audit.k8s.io/v1
kind: Policy
rules:
  - level: Metadata
    verbs: ["create"]
    resources:
      - group: "authorization.k8s.io"
        resources: ["subjectaccessreviews", "selfsubjectaccessreviews", "localsubjectaccessreviews"]
  - level: RequestResponse
    verbs: ["get", "list", "watch", "create", "update", "patch", "delete"]
    resources:
      - group: "rbac.authorization.k8s.io"
        resources: ["roles", "rolebindings", "clusterroles", "clusterrolebindings"]
  - level: Metadata
    verbs: ["create", "update", "delete"]
    resources:
      - group: ""
        resources: ["serviceaccounts"]
  - level: None
EOF

sudo tee /var/lib/rancher/rke2/server/audit/audit-webhook-config.yaml << 'EOF'
apiVersion: v1
kind: Config
clusters:
- name: audit-collector
  cluster:
    server: http://127.0.0.1:8030/k8s-audit
contexts:
- context:
    cluster: audit-collector
    user: ""
  name: default-context
current-context: default-context
preferences: {}
users: []
EOF

Configure RKE2 to use the audit policy and webhook.

Edit or create /etc/rancher/rke2/config.yaml:

kube-apiserver-arg:
  - "audit-policy-file=/var/lib/rancher/rke2/server/audit/audit-policy.yaml"
  - "audit-webhook-config-file=/var/lib/rancher/rke2/server/audit/audit-webhook-config.yaml"
  - "audit-webhook-batch-max-size=1"
kube-apiserver-extra-mount:
  - "/var/lib/rancher/rke2/server/audit:/var/lib/rancher/rke2/server/audit:ro"

Restart RKE2 to apply the changes.
```
sudo systemctl restart rke2-server
```

Verify the configuration.

sudo systemctl status rke2-server

# Check kube-apiserver flags
sudo /var/lib/rancher/rke2/bin/kubectl --kubeconfig /etc/rancher/rke2/rke2.yaml \
  get pod -n kube-system -l component=kube-apiserver -o yaml | grep -E "audit-policy|audit-webhook"