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Integration kubelogin and Active Directory

Overview

kubelogin is helper tool for kubernetes and oidc integration. It makes easy to login Open ID Provider. This document describes how dex work with kubelogin and Active Directory.

examples/config-ad-kubelogin.yaml is sample configuration to integrate Active Directory and kubelogin.

Precondition

  1. Active Directory You should have Active Directory or LDAP has Active Directory compatible schema such as samba ad. You may have user objects and group objects in AD. Please ensure TLS is enabled.

  2. Install kubelogin Download kubelogin from https://github.com/int128/kubelogin/releases . Install it to your terminal.

Getting started

Generate certificate and private key

Create OpenSSL conf req.conf as follow:

[req]
req_extensions = v3_req
distinguished_name = req_distinguished_name

[req_distinguished_name]

[ v3_req ]
basicConstraints = CA:FALSE
keyUsage = nonRepudiation, digitalSignature, keyEncipherment
subjectAltName = @alt_names

[alt_names]
DNS.1 = dex.example.com

Please replace dex.example.com to your favorite hostname. Generate certificate and private key by following command.

$ openssl req -new -x509 -sha256 -days 3650 -newkey rsa:4096 -extensions v3_req -out openid-ca.pem -keyout openid-key.pem -config req.cnf -subj "/CN=kube-ca" -nodes
$ ls openid*
openid-ca.pem openid-key.pem

Modify dex config

Modify following host, bindDN and bindPW in examples/config-ad-kubelogin.yaml.

connectors:
- type: ldap
  name: OpenLDAP
  id: ldap
  config:
    host: ldap.example.com:636

    # No TLS for this setup.
    insecureNoSSL: false
    insecureSkipVerify: true

    # This would normally be a read-only user.
    bindDN: cn=Administrator,cn=users,dc=example,dc=com
    bindPW: admin0!

Run dex

$ bin/dex serve examples/config-ad-kubelogin.yaml

Configure kubernetes with oidc

Copy openid-ca.pem to /etc/ssl/certs/openid-ca.pem on master node.

Use the following flags to point your API server(s) at dex. dex.example.com should be replaced by whatever DNS name or IP address dex is running under.

--oidc-issuer-url=https://dex.example.com:32000/dex
--oidc-client-id=kubernetes
--oidc-ca-file=/etc/ssl/certs/openid-ca.pem
--oidc-username-claim=email
--oidc-groups-claim=groups

Then restart API server(s).

See https://kubernetes.io/docs/reference/access-authn-authz/authentication/ for more detail.

Set up kubeconfig

Add a new user to the kubeconfig for dex authentication:

$ kubectl config set-credentials oidc \
    --exec-api-version=client.authentication.k8s.io/v1beta1 \
    --exec-command=kubectl \
    --exec-arg=oidc-login \
    --exec-arg=get-token \
    --exec-arg=--oidc-issuer-url=https://dex.example.com:32000/dex \
    --exec-arg=--oidc-client-id=kubernetes \
    --exec-arg=--oidc-client-secret=ZXhhbXBsZS1hcHAtc2VjcmV0 \
    --exec-arg=--extra-scope=profile \
    --exec-arg=--extra-scope=email \
    --exec-arg=--extra-scope=groups \
    --exec-arg=--certificate-authority-data=$(base64 -w 0 openid-ca.pem)

Please confirm --oidc-issuer-url, --oidc-client-id, --oidc-client-secret and --certificate-authority-data are same as values in config-ad-kubelogin.yaml.

Run the following command:

$ kubectl --user=oidc cluster-info

It launches the browser and navigates it to http://localhost:8000. Please log in with your AD account (eg. test@example.com ) and password. After login and grant, you can access the cluster.

You can switch the current context to dex authentication.

$ kubectl config set-context --current --user=oidc