Kubernetes 审计（Audit）提供了安全相关的时序操作记录，支持日志和 webhook 两种格式，并可以通过审计策略自定义事件类型。

审计日志

通过配置 kube-apiserver 的下列参数开启审计日志

  • audit-log-path：审计日志路径
  • audit-log-maxage：旧日志最长保留天数
  • audit-log-maxbackup：旧日志文件最多保留个数
  • audit-log-maxsize：日志文件最大大小（单位 MB），超过后自动做轮转（默认为 100MB）

每条审计记录包括两行

  • 请求行包括：唯一 ID 和请求的元数据（如源 IP、用户名、请求资源等）
  • 响应行包括：唯一 ID（与请求 ID 一致）和响应的元数据（如 HTTP 状态码）

比如，admin 用户查询默认 namespace 的 Pod 列表的审计日志格式为

  1. 2017-03-21T03:57:09.106841886-04:00 AUDIT: id="c939d2a7-1c37-4ef1-b2f7-4ba9b1e43b53" ip="127.0.0.1" method="GET" user="admin" groups="\"system:masters\",\"system:authenticated\""as="<self>"asgroups="<lookup>"namespace="default"uri="/api/v1/namespaces/default/pods"
  2. 2017-03-21T03:57:09.108403639-04:00 AUDIT: id="c939d2a7-1c37-4ef1-b2f7-4ba9b1e43b53" response="200"

审计策略

v1.7 + 支持实验性的高级审计特性，可以自定义审计策略（选择记录哪些事件）和审计存储后端（日志和 webhook）等。开启方法为

  1. kube-apiserver ... --feature-gates=AdvancedAuditing=true

注意开启 AdvancedAuditing 后，日志的格式有一些修改，如新增了 stage 字段（包括 RequestReceived，ResponseStarted ，ResponseComplete，Panic 等）。

审计策略

审计策略选择记录哪些事件，设置方法为

  1. kube-apiserver ... --audit-policy-file=/etc/kubernetes/audit-policy.yaml

其中，设计策略的配置格式为

  1. rules:
  2.   # Don't log watch requests by the"system:kube-proxy" on endpoints or services
  3.   - level: None
  4.     users: ["system:kube-proxy"]
  5.     verbs: ["watch"]
  6.     resources:
  7.     - group: "" # core API group
  8.       resources: ["endpoints", "services"]
  10.   # Don't log authenticated requests to certain non-resource URL paths.
  11.   - level: None
  12.     userGroups: ["system:authenticated"]
  13.     nonResourceURLs:
  14.     - "/api*" # Wildcard matching.
  15.     - "/version"
  17.   # Log the request body of configmap changes in kube-system.
  18.   - level: Request
  19.     resources:
  20.     - group: "" # core API group
  21.       resources: ["configmaps"]
  22.     # This rule only applies to resources in the "kube-system" namespace.
  23.     # The empty string "" can be used to select non-namespaced resources.
  24.     namespaces: ["kube-system"]
  26.   # Log configmap and secret changes in all other namespaces at the Metadata level.
  27.   - level: Metadata
  28.     resources:
  29.     - group: "" # core API group
  30.       resources: ["secrets", "configmaps"]
  32.   # Log all other resources in core and extensions at the Request level.
  33.   - level: Request
  34.     resources:
  35.     - group: "" # core API group
  36.     - group: "extensions" # Version of group should NOT be included.
  38.   # A catch-all rule to log all other requests at the Metadata level.
  39.   - level: Metadata

在生产环境中，推荐参考 GCE 审计策略 配置。

审计存储后端

审计存储后端支持两种方式

  • 日志，配置 --audit-log-path 开启，格式为
  1. 2017-06-15T21:50:50.259470834Z AUDIT: id="591e9fde-6a98-46f6-b7bc-ec8ef575696d" stage="RequestReceived" ip="10.2.1.3" method="update" user="system:serviceaccount:kube-system:default" groups="\"system:serviceaccounts\",\"system:serviceaccounts:kube-system\",\"system:authenticated\""as="<self>"asgroups="<lookup>"namespace="kube-system"uri="/api/v1/namespaces/kube-system/endpoints/kube-controller-manager"response="<deferred>"
  2. 2017-06-15T21:50:50.259470834Z AUDIT: id="591e9fde-6a98-46f6-b7bc-ec8ef575696d" stage="ResponseComplete" ip="10.2.1.3" method="update" user="system:serviceaccount:kube-system:default" groups="\"system:serviceaccounts\",\"system:serviceaccounts:kube-system\",\"system:authenticated\""as="<self>"asgroups="<lookup>"namespace="kube-system"uri="/api/v1/namespaces/kube-system/endpoints/kube-controller-manager"response="200"
  • webhook，配置 --audit-webhook-config-file=/etc/kubernetes/audit-webhook-kubeconfig --audit-webhook-mode=batch 开启，其中 audit-webhook-mode 支持 batch 和 blocking 两种格式，而 webhook 配置文件格式为
  1. # clusters refers to the remote service.
  2. clusters:
  3.   - name: name-of-remote-audit-service
  4.     cluster:
  5.       certificate-authority: /path/to/ca.pem  # CA for verifying the remote service.
  6.       server: https://audit.example.com/audit # URL of remote service to query. Must use 'https'.
  8. # users refers to the API server's webhook configuration.
  9. users:
  10.   - name: name-of-api-server
  11.     user:
  12.       client-certificate: /path/to/cert.pem # cert for the webhook plugin to use
  13.       client-key: /path/to/key.pem          # key matching the cert
  15. # kubeconfig files require a context. Provide one for the API server.
  16. current-context: webhook
  17. contexts:
  18. - context:
  19.     cluster: name-of-remote-audit-service
  20.     user: name-of-api-sever
  21.   name: webhook

所有的事件以 JSON 格式 POST 给 webhook server，如

  1. {
  2.   "kind": "EventList",
  3.   "apiVersion": "audit.k8s.io/v1alpha1",
  4.   "items": [
  5.     {
  6.       "metadata": {
  7.         "creationTimestamp": null
  8.       },
  9.       "level": "Metadata",
  10.       "timestamp": "2017-06-15T23:07:40Z",
  11.       "auditID": "4faf711a-9094-400f-a876-d9188ceda548",
  12.       "stage": "ResponseComplete",
  13.       "requestURI": "/apis/rbac.authorization.k8s.io/v1beta1/namespaces/kube-public/rolebindings/system:controller:bootstrap-signer",
  14.       "verb": "get",
  15.       "user": {
  16.         "username": "system:apiserver",
  17.         "uid": "97a62906-e4d7-4048-8eda-4f0fb6ff8f1e",
  18.         "groups": [
  19.           "system:masters"
  20.         ]
  21.       },
  22.       "sourceIPs": [
  23.         "127.0.0.1"
  24.       ],
  25.       "objectRef": {
  26.         "resource": "rolebindings",
  27.         "namespace": "kube-public",
  28.         "name": "system:controller:bootstrap-signer",
  29.         "apiVersion": "rbac.authorization.k8s.io/v1beta1"
  30.       },
  31.       "responseStatus": {
  32.         "metadata": {},
  33.         "code": 200
  34.       }
  35.     }
  36.   ]
  37. }