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Container Service for Kubernetes:Use cluster auditing in registered clusters

Last Updated:May 08, 2024

The audit log of an API server in a Kubernetes cluster helps administrators track operations performed by different users. This plays an important role in the security and maintenance of the cluster. This topic describes how to configure cluster auditing, how to use Log Service to collect and analyze audit logs, how to set custom alert rules based on audit logs, and how to disable cluster auditing.

Prerequisites

A registered cluster is created and an external Kubernetes cluster is connected to the registered cluster. For more information, see Create a registered cluster in the ACK console.

Step 1: Configure an audit policy for master nodes

Log on to a master node and modify the /etc/kubernetes/audit-policy.yaml file based on the following template. You must also perform this step on the other master nodes.

apiVersion: audit.k8s.io/v1beta1 # This is required.
kind: Policy
# Don't generate audit events for all requests in RequestReceived stage.
omitStages:
  - "RequestReceived"
rules:
  # The following requests were manually identified as high-volume and low-risk,
  # so drop them.
  - level: None
    users: ["system:kube-proxy"]
    verbs: ["watch"]
    resources:
      - group: "" # core
        resources: ["endpoints", "services"]
  - level: None
    users: ["system:unsecured"]
    namespaces: ["kube-system"]
    verbs: ["get"]
    resources:
      - group: "" # core
        resources: ["configmaps"]
  - level: None
    users: ["kubelet"] # legacy kubelet identity
    verbs: ["get"]
    resources:
      - group: "" # core
        resources: ["nodes"]
  - level: None
    userGroups: ["system:nodes"]
    verbs: ["get"]
    resources:
      - group: "" # core
        resources: ["nodes"]
  - level: None
    users:
      - system:kube-controller-manager
      - system:kube-scheduler
      - system:serviceaccount:kube-system:endpoint-controller
    verbs: ["get", "update"]
    namespaces: ["kube-system"]
    resources:
      - group: "" # core
        resources: ["endpoints"]
  - level: None
    users: ["system:apiserver"]
    verbs: ["get"]
    resources:
      - group: "" # core
        resources: ["namespaces"]
  # Don't log these read-only URLs.
  - level: None
    nonResourceURLs:
      - /healthz*
      - /version
      - /swagger*
  # Don't log events requests.
  - level: None
    resources:
      - group: "" # core
        resources: ["events"]
  # Secrets, ConfigMaps, and TokenReviews can contain sensitive & binary data,
  # so only log at the Metadata level.
  - level: Metadata
    resources:
      - group: "" # core
        resources: ["secrets", "configmaps"]
      - group: authentication.k8s.io
        resources: ["tokenreviews"]
  # Get repsonses can be large; skip them.
  - level: Request
    verbs: ["get", "list", "watch"]
    resources:
      - group: "" # core
      - group: "admissionregistration.k8s.io"
      - group: "apps"
      - group: "authentication.k8s.io"
      - group: "authorization.k8s.io"
      - group: "autoscaling"
      - group: "batch"
      - group: "certificates.k8s.io"
      - group: "extensions"
      - group: "networking.k8s.io"
      - group: "policy"
      - group: "rbac.authorization.k8s.io"
      - group: "settings.k8s.io"
      - group: "storage.k8s.io"
  # Default level for known APIs
  - level: RequestResponse
    resources:
      - group: "" # core
      - group: "admissionregistration.k8s.io"
      - group: "apps"
      - group: "authentication.k8s.io"
      - group: "authorization.k8s.io"
      - group: "autoscaling"
      - group: "batch"
      - group: "certificates.k8s.io"
      - group: "extensions"
      - group: "networking.k8s.io"
      - group: "policy"
      - group: "rbac.authorization.k8s.io"
      - group: "settings.k8s.io"
      - group: "storage.k8s.io"
  # Default level for all other requests.
  - level: Metadata

Step 2: Modify the kube-apiserver configurations on master nodes

Log on to a master node and modify the /etc/kubernetes/manifests/kube-apiserver.yaml file based on the following description. You must also perform this step on the other master nodes.

  • Add --audit-log-* parameters to the command section:

    ...
    spec:
      containers:
      - command:
        - kube-apiserver
        - --audit-log-maxbackup=10
        - --audit-log-maxsize=100
        - --audit-log-path=/var/log/kubernetes/kubernetes.audit
        - --audit-log-maxage=30
        - --audit-policy-file=/etc/kubernetes/audit-policy.yaml
        ...
  • Add the aliyun_logs_audit-* parameters to the env section.

    ...
    spec:
      containers:
      - command:
        - kube-apiserver
        - --audit-log-maxbackup=10
        - --audit-log-maxsize=100
        - --audit-log-path=/var/log/kubernetes/kubernetes.audit
        - --audit-log-maxage=30
        - --audit-policy-file=/etc/kubernetes/audit-policy.yaml
        ...
        ...
        env:
        - name: aliyun_logs_audit-${cluster_id}
          value: /var/log/kubernetes/kubernetes.audit
        - name: aliyun_logs_audit-${cluster_id}_tags
          value: audit=apiserver
        - name: aliyun_logs_audit-${cluster_id}_product
          value: k8s-audit
        - name: aliyun_logs_audit-${cluster_id}_jsonfile
          value: "true"
        image: registry-vpc.cn-shenzhen.aliyuncs.com/acs/kube-apiserver:v1.20.4-aliyun.1
    Important

    You must replace {cluster_id} with the ID of your cluster. For more information about how to obtain the ID of your cluster, see View cluster information.

  • Use the following template to mount /etc/kubernetes/audit-policy.yaml to the pods of kube-apiserver:

    ...
    spec:
      containers:
      - command:
        - kube-apiserver
        - --audit-log-maxbackup=10
        - --audit-log-maxsize=100
        - --audit-log-path=/var/log/kubernetes/kubernetes.audit
        - --audit-log-maxage=30
        - --audit-policy-file=/etc/kubernetes/audit-policy.yaml
        ...
        ...
        env:
        - name: aliyun_logs_audit-${cluster_id}
          value: /var/log/kubernetes/kubernetes.audit
        - name: aliyun_logs_audit-${cluster_id}_tags
          value: audit=apiserver
        - name: aliyun_logs_audit-${cluster_id}_product
          value: k8s-audit
        - name: aliyun_logs_audit-${cluster_id}_jsonfile
          value: "true"
        image: registry-vpc.cn-shenzhen.aliyuncs.com/acs/kube-apiserver:v1.20.4-aliyun.1
        ...
        ...
        volumeMounts:
        - mountPath: /var/log/kubernetes
          name: k8s-audit
        - mountPath: /etc/kubernetes/audit-policy.yaml
          name: audit-policy
          readOnly: true
        ...
        ...
      volumes:
      - hostPath:
          path: /var/log/kubernetes
          type: DirectoryOrCreate
        name: k8s-audit
      - hostPath:
          path: /etc/kubernetes/audit-policy.yaml
          type: FileOrCreate
        name: audit-policy
      ...

Step 3: Install the logtail-ds component

For more information about how to install the logtail-ds component, see Step 2: Install logtail-ds.

What to do next

For more information about how to use cluster auditing and view audit logs, see Work with cluster auditing.