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Enabling the API Audit Log in Downstream Clusters

Kubernetes auditing provides a security-relevant chronological set of records about a cluster. Kube-apiserver performs auditing. Requests generate an event at each stage of its execution, which is then preprocessed according to a certain policy and written to a backend. The policy determines what’s recorded and the backend persists the records.

You might want to configure the audit log as part of compliance with the Center for Internet Security (CIS) Kubernetes Benchmark controls.

For configuration details, refer to the official Kubernetes documentation.

You can set audit-policy-file in the configuration file. Rancher delivers the file to the path /var/lib/rancher/rke2/etc/config-files/audit-policy-file in control plane nodes, and sets the proper options in the RKE2 server.

Example:

apiVersion: provisioning.cattle.io/v1
kind: Cluster
spec:
  rkeConfig:
    machineGlobalConfig:
      audit-policy-file: |
        apiVersion: audit.k8s.io/v1 
        kind: Policy 
        rules: 
        - level: RequestResponse
          resources:
          - group: ""
            resources: 
            - pods

Method 2: Use the Directives, machineSelectorFiles and machineGlobalConfig​

note

This feature is available in Rancher v2.7.2 and later.

You can use machineSelectorFiles to deliver the audit policy file to the control plane nodes, and machineGlobalConfig to set the options on kube-apiserver.

As a prerequisite, you must create a secret or configmap to be the source of the audit policy.

The secret or configmap must meet the following requirements:

  1. It must be in the fleet-default namespace where the Cluster object exists.
  2. It must have the annotation rke.cattle.io/object-authorized-for-clusters: <cluster-name1>,<cluster-name2> which permits the target clusters to use it.
tip

Rancher Dashboard provides an easy-to-use form for creating the secret or configmap.

Example:

apiVersion: v1
data:
  audit-policy: >-
    IyBMb2cgYWxsIHJlcXVlc3RzIGF0IHRoZSBNZXRhZGF0YSBsZXZlbC4KYXBpVmVyc2lvbjogYXVkaXQuazhzLmlvL3YxCmtpbmQ6IFBvbGljeQpydWxlczoKLSBsZXZlbDogTWV0YWRhdGE=
kind: Secret
metadata:
  annotations:
    rke.cattle.io/object-authorized-for-clusters: cluster1
  name: <name1>
  namespace: fleet-default

Enable and configure the audit log by editing the cluster in YAML, and utilizing the machineSelectorFiles and machineGlobalConfig directives.

Example:

apiVersion: provisioning.cattle.io/v1
kind: Cluster
spec:
  rkeConfig:
    machineGlobalConfig:
      kube-apiserver-arg:
        - audit-policy-file=<customized-path>/dev-audit-policy.yaml
        - audit-log-path=<customized-path>/dev-audit.logs
    machineSelectorFiles:
      - fileSources:
          - configMap:
              name: ''
            secret:
              items:
                - key: audit-policy
                  path: <customized-path>/dev-audit-policy.yaml
              name: dev-audit-policy
        machineLabelSelector:
          matchLabels:
            rke.cattle.io/control-plane-role: 'true'
tip

You can also use the directive machineSelectorConfig with proper machineLabelSelectors to achieve the same effect.

For more information about cluster configuration, refer to the RKE2 cluster configuration reference pages.