A kubelet's HTTPS endpoint exposes APIs which give access to data of varying sensitivity, and allow you to perform operations with varying levels of power on the node and within containers.
This document describes how to authenticate and authorize access to the kubelet's HTTPS endpoint.
By default, requests to the kubelet's HTTPS endpoint that are not rejected by other configured authentication methods are treated as anonymous requests, and given a username of system:anonymous
and a group of system:unauthenticated
.
To disable anonymous access and send 401 Unauthorized
responses to unauthenticated requests:
--anonymous-auth=false
flagTo enable X509 client certificate authentication to the kubelet's HTTPS endpoint:
--client-ca-file
flag, providing a CA bundle to verify client certificates with--kubelet-client-certificate
and --kubelet-client-key
flagsTo enable API bearer tokens (including service account tokens) to be used to authenticate to the kubelet's HTTPS endpoint:
authentication.k8s.io/v1beta1
API group is enabled in the API server--authentication-token-webhook
and --kubeconfig
flagsTokenReview
API on the configured API server to determine user information from bearer tokensAny request that is successfully authenticated (including an anonymous request) is then authorized. The default authorization mode is AlwaysAllow
, which allows all requests.
There are many possible reasons to subdivide access to the kubelet API:
To subdivide access to the kubelet API, delegate authorization to the API server:
authorization.k8s.io/v1beta1
API group is enabled in the API server--authorization-mode=Webhook
and the --kubeconfig
flagsSubjectAccessReview
API on the configured API server to determine whether each request is authorizedThe kubelet authorizes API requests using the same request attributes approach as the apiserver.
The verb is determined from the incoming request's HTTP verb:
HTTP verb | request verb |
---|---|
POST | create |
GET, HEAD | get |
PUT | update |
PATCH | patch |
DELETE | delete |
The resource and subresource is determined from the incoming request's path:
Kubelet API | resource | subresource |
---|---|---|
/stats/* | nodes | stats |
/metrics/* | nodes | metrics |
/logs/* | nodes | log |
/spec/* | nodes | spec |
all others | nodes | proxy |
The namespace and API group attributes are always an empty string, and the resource name is always the name of the kubelet's Node
API object.
When running in this mode, ensure the user identified by the --kubelet-client-certificate
and --kubelet-client-key
flags passed to the apiserver is authorized for the following attributes:
© 2022 The Kubernetes Authors
Documentation Distributed under CC BY 4.0.
https://kubernetes.io/docs/reference/command-line-tools-reference/kubelet-authentication-authorization/