---
reviewers:
- timstclair
- deads2k
- liggitt
- ericchiang
title: Using Node Authorization
---

* TOC
{:toc}

Node authorization is a special-purpose authorization mode that specifically authorizes API requests made by kubelets.

## Overview

The Node authorizer allows a kubelet to perform API operations. This includes:

Read operations:

* services
* endpoints
* nodes
* pods
* secrets, configmaps, persistent volume claims and persistent volumes related to pods bound to the kubelet's node

Write operations:

* nodes and node status (enable the `NodeRestriction` admission plugin to limit a kubelet to modify its own node)
* pods and pod status (enable the `NodeRestriction` admission plugin to limit a kubelet to modify pods bound to itself)
* events

Auth-related operations:

* read/write access to the certificationsigningrequests API for TLS bootstrapping
* the ability to create tokenreviews and subjectaccessreviews for delegated authentication/authorization checks

In future releases, the node authorizer may add or remove permissions to ensure kubelets
have the minimal set of permissions required to operate correctly.

In order to be authorized by the Node authorizer, kubelets must use a credential that identifies them as 
being in the `system:nodes` group, with a username of `system:node:<nodeName>`.
This group and user name format match the identity created for each kubelet as part of 
[kubelet TLS bootstrapping](/docs/admin/kubelet-tls-bootstrapping/).

To enable the Node authorizer, start the apiserver with `--authorization-mode=Node`.

To limit the API objects kubelets are able to write, enable the [NodeRestriction](/docs/admin/admission-controllers#NodeRestriction) admission plugin by starting the apiserver with `--admission-control=...,NodeRestriction,...`

## Migration considerations

### Kubelets outside the `system:nodes` group

Kubelets outside the `system:nodes` group would not be authorized by the `Node` authorization mode,
and would need to continue to be authorized via whatever mechanism currently authorizes them.
The node admission plugin would not restrict requests from these kubelets.

### Kubelets with undifferentiated usernames

In some deployments, kubelets have credentials that place them in the `system:nodes` group,
but do not identify the particular node they are associated with,
because they do not have a username in the `system:node:...` format.
These kubelets would not be authorized by the `Node` authorization mode,
and would need to continue to be authorized via whatever mechanism currently authorizes them.

The `NodeRestriction` admission plugin would ignore requests from these kubelets,
since the default node identifier implementation would not consider that a node identity.

### Upgrades from previous versions using RBAC

Upgraded pre-1.7 clusters using [RBAC](/docs/admin/authorization/rbac/) will continue functioning as-is because the `system:nodes` group binding will already exist.

If a cluster admin wishes to start using the `Node` authorizer and `NodeRestriction` admission plugin
to limit node access to the API, that can be done non-disruptively:

1. Enable the `Node` authorization mode (`--authorization-mode=Node,RBAC`) and the `NodeRestriction` admission plugin
2. Ensure all kubelets' credentials conform to the group/username requirements
3. Audit apiserver logs to ensure the `Node` authorizer is not rejecting requests from kubelets (no persistent `NODE DENY` messages logged)
4. Delete the `system:node` cluster role binding

### RBAC Node Permissions

In 1.6, the `system:node` cluster role was automatically bound to the `system:nodes` group when using the [RBAC Authorization mode](/docs/admin/authorization/rbac/).

In 1.7, the automatic binding of the `system:nodes` group to the `system:node` role is deprecated
because the node authorizer accomplishes the same purpose with the benefit of additional restrictions
on secret and configmap access. If the `Node` and `RBAC` authorization modes are both enabled,
the automatic binding of the `system:nodes` group to the `system:node` role is not created in 1.7.

In 1.8, the binding will not be created at all.

When using RBAC, the `system:node` cluster role will continue to be created,
for compatibility with deployment methods that bind other users or groups to that role.
