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开启/关闭审计日志

默认 Kubernetes 集群不会输出审计日志信息。通过以下配置,可以开启 Kubernetes 的审计日志功能。

  1. 准备审计日志的 Policy 文件
  2. 修改 API 服务器配置文件,开启审计日志
  3. 重启并验证

准备审计日志 Policy 文件

审计日志所需的 Policy 配置 YAML 文件如下所示:

apiVersion: audit.k8s.io/v1
kind: Policy
# Don't generate audit events for all requests in RequestReceived stage.
omitStages:
  - "ResponseStarted"
  - "RequestReceived"
  - "Panic"
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", "services/status"]
  - level: None
    # Ingress controller reads `configmaps/ingress-uid` through the unsecured port.
    # TODO(#46983): Change this to the ingress controller service account.
    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", "nodes/status"]
  - level: None
    userGroups: ["system:nodes"]
    verbs: ["get"]
    resources:
      - group: "" # core
        resources: ["nodes", "nodes/status"]
  - 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", "namespaces/status", "namespaces/finalize"]
  # Don't log HPA fetching metrics.
  - level: None
    users:
      - system:kube-controller-manager
    verbs: ["get", "list"]
    resources:
      - group: "metrics.k8s.io"
  # 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"]

  # new start
  # 忽略所有访问非认证端口的 API,通常是系统组件如 Kube-Controller 等。
  - level: None
    users: ["system:unsecured"]

  # 忽略 kube-admin 的审计日志
  - level: None
    users: ["kube-admin"]
  # 忽略所有资源状态更新的 API need add
  - level: None
    resources:
    - group: "" # core
      resources: ["events", "nodes/status", "pods/status", "services/status"]
    - group: "authorization.k8s.io"
      resources: ["selfsubjectrulesreviews"]
  # 忽略leases need add
  - level: None
    resources:
    - group: "coordination.k8s.io"
      resources: ["leases"]
  - level: Request
    verbs: ["create", "update", "patch", "delete"]
    users: ["kube-admin"]
  #new end

  # 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"]
    omitStages:
      - "RequestReceived"
  # Get responses can be large; skip them.
  - level: Request
    verbs: ["get", "list", "watch"]
    resources:
      - group: "" # core
      - group: "admissionregistration.k8s.io"
      - group: "apiextensions.k8s.io"
      - group: "apiregistration.k8s.io"
      - group: "apps"
      - group: "authentication.k8s.io"
      - group: "authorization.k8s.io"
      - group: "autoscaling"
      - group: "batch"
      - group: "certificates.k8s.io"
      - group: "extensions"
      - group: "metrics.k8s.io"
      - group: "networking.k8s.io"
      - group: "policy"
      - group: "rbac.authorization.k8s.io"
      - group: "settings.k8s.io"
      - group: "storage.k8s.io"
    omitStages:
      - "RequestReceived"
  # Default level for known APIs
  - level: RequestResponse
    resources:
      - group: "" # core
      - group: "admissionregistration.k8s.io"
      - group: "apiextensions.k8s.io"
      - group: "apiregistration.k8s.io"
      - group: "apps"
      - group: "authentication.k8s.io"
      - group: "authorization.k8s.io"
      - group: "autoscaling"
      - group: "batch"
      - group: "certificates.k8s.io"
      - group: "extensions"
      - group: "metrics.k8s.io"
      - group: "networking.k8s.io"
      - group: "policy"
      - group: "rbac.authorization.k8s.io"
      - group: "settings.k8s.io"
      - group: "storage.k8s.io"
    omitStages:
      - "RequestReceived"
  # Default level for all other requests.
  - level: Metadata
    omitStages:
      - "RequestReceived"

将以上审计日志文件放到 /etc/kubernetes/audit-policy/ 文件夹下,并取名为 apiserver-audit-policy.yaml

配置 API 服务器

打开 API 服务器的配置文件 kube-apiserver.yaml,一般会在 /etc/kubernetes/manifests/ 文件夹下,并添加以下配置信息:

这一步操作前请备份 kube-apiserver.yaml,并且备份的文件不能放在 /etc/kubernetes/manifests/ 下,建议放在 /etc/kubernetes/tmp

  1. spec.containers.command 下添加命令:

    --audit-log-maxage=30
    --audit-log-maxbackup=1
    --audit-log-maxsize=100
    --audit-log-path=/var/log/audit/kube-apiserver-audit.log
    --audit-policy-file=/etc/kubernetes/audit-policy/apiserver-audit-policy.yaml
    
  2. spec.containers.volumeMounts 下添加:

    - mountPath: /var/log/audit
      name: audit-logs
    - mountPath: /etc/kubernetes/audit-policy
      name: audit-policy
    
  3. spec.volumes 下添加:

    - hostPath:
        path: /var/log/kubernetes/audit
        type: ""
      name: audit-logs
    - hostPath:
        path: /etc/kubernetes/audit-policy
        type: ""
      name: audit-policy
    

测试并验证

稍等一会,API 服务器会自动重启,在 /var/log/kubernetes/audit 目录下查看是否有审计日志生成。

如果想关闭,去掉 spec.containers.command 中的相关命令即可。

采集审计日志

通过 FluentBit 来采集审计日志。默认 FluentBit 不会会采集 /var/log/kubernetes/audit 下的日志文件(Kubernetes 审计日志)。

如需开启,按以下步骤操作:

  1. 查看当前 chart 版本并保存当前 value
  2. 修改 chart value
  3. 重启所有 Pod

具体步骤如下:

  1. 保存当前 value

    helm get values insight-agent -n insight-system -o yaml > insight-agent-values-bak.yaml
    
  2. 获取当前版本号 ${insight_version_code},然后更新配置

    insight_version_code=`helm list -n insight-system |grep insight-agent | awk {'print $10'}` 
    
    helm upgrade --install --create-namespace --version ${insight_version_code} --cleanup-on-fail insight-agent insight-release/insight-agent -n insight-system -f insight-agent-values-bak.yaml --set global.exporters.auditLog.kubeAudit.enabled=true 
    

    如果因为版本未找到而 upgrade 失败,请检查命令中使用的 helm repo 是否有这版本,若没有,请尝试更新helm repo后重试

    helm repo update insight-release
    
  3. 重启所有 Pod

    重启所有 master 节点的 FluentBit Pod,重启后的 FluentBit 将会采集 /var/log/kubernetes/audit 下的日志。

    此外,如果想停止全局管理的审计日志采集,可以执行 kubectl edit cm insight-agent-fluent-bit-config -n insight-system,删除以下 INPUT 即可:

    [INPUT]
    Name               tail
    Tag                audit_log.ghippo.*
    Parser             docker
    Path               /var/log/containers/*_ghippo-system_audit-log*.log
    DB                 /run/flb_audit.db
    Mem_Buf_Limit      15MB
    Buffer_Chunk_Size  1MB
    Buffer_Max_Size    5MB
    #DB.Sync           Normal
    Refresh_Interval   10
    

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