Access control

Once Dashboard is installed and accessible we can focus on configuring access control to the cluster resources for users.

Introduction

Kubernetes supports few ways of authenticating and authorizing users. You can read about them here and here. Authorization is handled by Kubernetes API server. Dashboard only acts as a proxy and passes all auth information to it. In case of forbidden access corresponding warnings will be displayed in Dashboard.

Default Dashboard privileges

• get, update and delete permissions for Secrets named kubernetes-dashboard-key-holder, kubernetes-dashboard-certs and kubernetes-dashboard-csrf in kubernetes-dashboard namespace.
• get and update permissions for the Config Map named kubernetes-dashboard-settings in kubernetes-dashboard namespace.
• get permission for services/proxy in order to allow heapster and dashboard-metrics-scraper services in kubernetes-dashboard namespace required to gather metrics.
• get, list and watch permissions for metrics.k8s.io API in order to allow dashboard-metrics-scraper to gather metrics from the metrics-server.

Authentication

Kubernetes Dashboard supports a few different ways of authenticating users:

• Authorization header passed in every request to Dashboard. Supported from release 1.6. Has the highest priority. If present, login view will be skipped.
• Bearer Token that can be used on Dashboard login view.
• Username/password that can be used on Dashboard login view.
• Kubeconfig file that can be used on Dashboard login view.

Login view

In case you are using the latest recommended installation then login functionality will be enabled by default. In any other case and if you prefer to configure certificates manually you need to pass --tls-cert-file and --tls-cert-key flags to Dashboard. HTTPS endpoint will be exposed on port 8443 of Dashboard container. You can change it by providing --port flag.

Using Skip option will make Dashboard use privileges of Service Account used by Dashboard. Skip button is disabled by default since 1.10.1. Use --enable-skip-login dashboard flag to display it.

Authorization header

Using authorization header is the only way to make Dashboard act as an user, when accessing it over HTTP. Note that there are some risks since plain HTTP traffic is vulnerable to MITM attacks.

To make Dashboard use authorization header you simply need to pass Authorization: Bearer <token> in every request to Dashboard. This can be achieved i.e. by configuring reverse proxy in front of Dashboard. Proxy will be responsible for authentication with identity provider and will pass generated token in request header to Dashboard. Note that Kubernetes API server needs to be configured properly to accept these tokens.

To quickly test it check out Requestly Chrome browser plugin that allows to manually modify request headers.

IMPORTANT: Authorization header will not work if Dashboard is accessed through API server proxy. Both kubectl proxy and API Server way of accessing Dashboard described in Accessing Dashboard guide will not work. It is due to the fact that once request reaches API server all additional headers are dropped.

Bearer Token

It is recommended to get familiar with Kubernetes authentication documentation first to find out how to get token, that can be used to login. In example every Service Account has a Secret with valid Bearer Token that can be used to login to Dashboard.

Recommended lecture to find out how to create Service Account and grant it privileges:

• Service Account Tokens
• Role and ClusterRole
• Service Account Permissions

To create sample user and to get its token, see Creating sample user guide.

Basic

Basic authentication is disabled by default. The reason is that Kubernetes API server needs to be configured with authorization mode ABAC and --basic-auth-file flag provided. Without that API server automatically falls back to anonymous user and there is no way to check if provided credentials are valid.

In order to enable basic auth in Dashboard --authentication-mode=basic flag has to be provided. By default it is set to --authentication-mode=token.

Note: Basic authentication with --basic-auth-file has been deprecated since Kubernetes v1.19. For similar functionality to --basic-auth-file flag, use --token-auth-file with Static Token File.

Kubeconfig

This method of logging in is provided for convenience. Only authentication options specified by --authentication-mode flag are supported in kubeconfig file. In case it is configured to use any other way, error will be shown in Dashboard. External identity providers or certificate-based authentication are not supported at this time.

Admin privileges

IMPORTANT: Make sure that you know what you are doing before proceeding. Granting admin privileges to Dashboard’s Service Account might be a security risk.

You can grant full admin privileges to Dashboard’s Service Account by creating below ClusterRoleBinding. Copy the YAML file based on chosen installation method and save as, i.e. dashboard-admin.yaml. Use kubectl create -f dashboard-admin.yaml to deploy it. Afterwards you can use Skip option on login page to access Dashboard.

Official release

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: kubernetes-dashboard
  namespace: kubernetes-dashboard
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
  - kind: ServiceAccount
    name: kubernetes-dashboard
    namespace: kubernetes-dashboard

Development release

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: kubernetes-dashboard-head
  namespace: kubernetes-dashboard-head
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
  - kind: ServiceAccount
    name: kubernetes-dashboard-head
    namespace: kubernetes-dashboard-head

Copyright 2019 The Kubernetes Dashboard Authors