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Kubelet authentication/authorization


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.

Kubelet authentication

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:

To enable X509 client certificate authentication to the kubelet’s HTTPS endpoint:

To enable API bearer tokens (including service account tokens) to be used to authenticate to the kubelet’s HTTPS endpoint:

Kubelet authorization

Any 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:

The 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
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: