Control access using Microsoft Entra ID and Kubernetes RBAC

Applies to: AKS on Azure Stack HCI 23H2

You can configure Azure Kubernetes Service (AKS) to use Microsoft Entra ID for user authentication. In this configuration, you sign in to a Kubernetes cluster using a Microsoft Entra authentication token. Once authenticated, you can use the built-in Kubernetes role-based access control (Kubernetes RBAC) to manage access to namespaces and cluster resources based on a user's identity or group membership.

This article describes how to control access using Kubernetes RBAC in a Kubernetes cluster based on Microsoft Entra group membership in AKS. You create a demo group and users in Microsoft Entra ID. Then, you create roles and role bindings in the cluster to grant the appropriate permissions to create and view resources.

Prerequisites

Before you set up Kubernetes RBAC using Microsoft Entra ID, you must have the following prerequisites:

• An AKS enabled by Azure Arc cluster. If you need to set up your cluster, see the instructions for using the Azure portal or Azure CLI.
• Azure CLI installed and configured. If you need to install CLI or upgrade, see Install Azure CLI.
• Azure CLI and the connectedk8s extension. The Azure command-line interface (Azure CLI) is a set of commands used to create and manage Azure resources. To check whether you have the Azure CLI, open a command line tool, and type: az -v. Also, install the connectedk8s extension in order to open a channel to your Kubernetes cluster. For installation instructions, see How to install the Azure CLI.
• Kubectl. The Kubernetes command-line tool, kubectl, enables you to run commands that target your Kubernetes clusters. To check whether you have installed kubectl, open a command line tool, and type: kubectl version --client. Make sure your kubectl client version is at least v1.24.0. For installation instructions, see kubectl.
• You can access your Kubernetes cluster with the specified permissions either with direct mode or proxy mode.
  • To access the Kubernetes cluster directly using the az aksarc get-credentials command, you need the Microsoft.HybridContainerService/provisionedClusterInstances/listUserKubeconfig/action, which is included in the Azure Kubernetes Service Arc Cluster User role permissions
  • To access the Kubernetes cluster from anywhere with a proxy mode using az connectedk8s proxy command, you need the Microsoft.Kubernetes/connectedClusters/listClusterUserCredential/action, which is included in Azure Arc-enabled Kubernetes Cluster User role permission. Meanwhile, you need to verify that the agents and the machine performing the onboarding process meet the network requirements in Azure Arc-enabled Kubernetes network requirements.

Optional first steps

If you don't already have a Microsoft Entra group that contains members, you might want to create a group and add some members, so that you can follow the instructions in this article.

To demonstrate working with Microsoft Entra ID and Kubernetes RBAC, you can create a Microsoft Entra group for application developers that can be used to show how Kubernetes RBAC and Microsoft Entra ID control access to cluster resources. In production environments, you can use existing users and groups within a Microsoft Entra tenant.

Create a demo group in Microsoft Entra ID

First, create the group in Microsoft Entra ID in your tenant for the application developers using the az ad group create command. The following example prompts you to sign in to your Azure tenant and then creates a group named appdev:

az login
az ad group create --display-name appdev --mail-nickname appdev

Add users to your group

With the example group created in Microsoft Entra ID for application developers, add a user to the appdev group. You use this user account to sign in to the AKS cluster and test the Kubernetes RBAC integration.

Add a user to the appdev group created in the previous section using the az ad group member add command. If you quit your session, reconnect to Azure using az login.

$AKSDEV_ID = az ad user create --display-name <name> --password <strongpassword> --user-principal-name <name>@contoso.onmicrosoft.com
az ad group member add --group appdev --member-id $AKSDEV_ID

Create a custom Kubernetes RBAC role binding on the AKS cluster resource for the Microsoft Entra group

Configure the AKS cluster to allow your Microsoft Entra group to access the cluster. If you want to add a group and users, see Create demo groups in Microsoft Entra ID.

1. Use the az aksarc get-credentials command to get the cluster admin credentials:

   az aksarc get-credentials --name "$aks_cluster_name" --resource-group "$resource_group_name" --admin
   

2. Create a namespace in the Kubernetes cluster using the kubectl create namespace command. The following example creates a namespace named dev:

   kubectl create namespace dev
   

In Kubernetes, Roles define the permissions to grant, and RoleBindings apply the permissions to desired users or groups. These assignments can be applied to a given namespace or across an entire cluster. For more information, see Using Kubernetes RBAC authorization.

Create a role for the dev namespace. This role grants full permissions to the namespace. In production environments, you might want to specify more granular permissions for different users or groups.

1. Create a file named role-dev-namespace.yaml and copy/paste the following YAML manifest:

   kind: Role
   apiVersion: rbac.authorization.k8s.io/v1
   metadata:
     name: dev-user-full-access
     namespace: dev
   rules:
   - apiGroups: ["", "extensions", "apps"]
     resources: ["*"]
     verbs: ["*"]
   - apiGroups: ["batch"]
     resources:
     - jobs
     - cronjobs
     verbs: ["*"]
   

2. Create the role using the kubectl apply command, and specify the filename of your YAML manifest:

   kubectl apply -f role-dev-namespace.yaml
   

3. Get the resource ID for the appdev group using the az ad group show command. This group is set as the subject of a RoleBinding in the next step:

   az ad group show --group appdev --query objectId -o tsv
   

   The az ad group show command returns the value you use as groupObjectId:

   38E5FA30-XXXX-4895-9A00-050712E3673A
   

4. Create a file named rolebinding-dev-namespace.yaml, and copy/paste the following YAML manifest. You establish the role binding that enables the appdev group to use the role-dev-namespace role for namespace access. On the last line, replace groupObjectId with the group object ID produced by the az ad group show command:

   kind: RoleBinding
   apiVersion: rbac.authorization.k8s.io/v1
   metadata:
     name: dev-user-access
     namespace: dev
   roleRef:
     apiGroup: rbac.authorization.k8s.io
     kind: Role
     name: dev-user-full-access
   subjects:
   - kind: Group
     namespace: dev
     name: groupObjectId
   

   Tip

   If you want to create the RoleBinding for a single user, specify kind: User and replace groupObjectId with the user principal name (UPN) in the example.

5. Create the RoleBinding using the kubectl apply command and specify the filename of your YAML manifest:

   kubectl apply -f rolebinding-dev-namespace.yaml
   

   rolebinding.rbac.authorization.k8s.io/dev-user-access created
   

Use built-in Kubernetes RBAC roles for your AKS cluster resource

Kubernetes also provides built-in user-facing roles. These built-in roles include:

• Super-user roles (cluster-admin)
• Roles intended to be granted cluster-wide using ClusterRoleBindings
• Roles intended to be granted within particular namespaces using RoleBindings (admin, edit, view)

For more information about built-in Kubernetes RBAC roles, see Kubernetes RBAC user-facing roles.

User-facing roles

Default ClusterRole	Default ClusterRoleBinding	Description
cluster-admin	system:masters group	Allows super-user access, to perform any action on any resource. When used in a ClusterRoleBinding, this role gives full control over every resource in the cluster and in all namespaces. When used in a RoleBinding, it gives full control over every resource in the role binding's namespace, including the namespace itself.
admin	None	Allows admin access, intended to be granted within a namespace using a role binding. If used in a role binding, allows read/write access to most resources in a namespace, including the capability to create roles and role bindings within the namespace. This role doesn't allow write access to resource quota or to the namespace itself. This role also doesn't allow write access to endpoints in clusters created using Kubernetes v1.22+. For more information, see Write Access for Endpoints.
edit	None	Allows read/write access to most objects in a namespace. This role doesn't allow viewing or modifying roles or role bindings. However, this role allows accessing secrets and running pods as any ServiceAccount in the namespace, so it can be used to gain the API access levels of any ServiceAccount in the namespace. This role also doesn't allow write access to endpoints in clusters created using Kubernetes v1.22+. For more information, see Write Access for Endpoints.
view	None	Allows read-only access to see most objects in a namespace. It doesn't allow viewing roles or role bindings. This role doesn't allow viewing secrets, since reading the contents of secrets enables access to ServiceAccount credentials in the namespace, which would allow API access as any ServiceAccount in the namespace (a form of privilege escalation).

Use a built-in Kubernetes RBAC role with Microsoft Entra ID

To use a built-in Kubernetes RBAC role with Microsoft Entra ID, follow these steps:

1. Apply the built-in view Kubernetes RBAC role to your Microsoft Entra group:

   kubectl create clusterrolebinding <name of your cluster role binding> --clusterrole=view --group=<Azure AD group object ID>
   

2. Apply the built-in view Kubernetes RBAC role to each of your Microsoft Entra users:

   kubectl create clusterrolebinding <name of your cluster role binding> --clusterrole=view --user=<Azure AD user object ID>
   

Access the Kubernetes cluster

You can now access your Kubernetes cluster with the specified permissions, using either direct mode or proxy mode.

Access your cluster with kubectl (direct mode)

To access the Kubernetes cluster with the specified permissions, the Kubernetes operator needs the Microsoft Entra kubeconfig, which you can get using the az aksarc get-credentials command. This command provides access to the admin-based kubeconfig, as well as a user-based kubeconfig. The admin-based kubeconfig file contains secrets and should be securely stored and rotated periodically. On the other hand, the user-based Microsoft Entra ID kubeconfig doesn't contain secrets and can be distributed to users who connect from their client machines.

To run this Azure CLI command, you need the Microsoft.HybridContainerService/provisionedClusterInstances/listUserKubeconfig/action, which is included in the Azure Kubernetes Service Arc Cluster User role permissions:

az aksarc get-credentials -g $resource_group_name -n $aks_cluster_name --file <file-name>

Now, you can use kubectl to manage your cluster. For example, you can list the nodes in your cluster using kubectl get nodes. The first time you run it, you must sign in, as shown in the following example:

kubectl get nodes

Access your cluster from a client device (proxy mode)

To access the Kubernetes cluster from anywhere with a proxy mode using az connectedk8s proxy command, you need the Microsoft.Kubernetes/connectedClusters/listClusterUserCredential/action, which is included in the Azure Arc-enabled Kubernetes Cluster User role permission.

Run the following steps on another client device:

1. Sign in using Microsoft Entra authentication.

2. Get the cluster connect kubeconfig needed to communicate with the cluster from anywhere (from even outside the firewall surrounding the cluster):

   az connectedk8s proxy -n $aks_cluster_name -g $resource_group_name
   

   Note

   This command opens the proxy and blocks the current shell.

3. In a different shell session, use kubectl to send requests to the cluster:

   kubectl get pods -A
   

You should now see a response from the cluster containing the list of all pods under the default namespace.

For more information, see Access your cluster from a client device

Create and view cluster resources outside the assigned namespace

To attempt to view pods outside the dev namespace, use the kubectl get pods command with the --all-namespaces flag:

kubectl get pods --all-namespaces

The user's group membership doesn't have a Kubernetes role that allows this action. Without the permission, the command generates an error:

Error from server (Forbidden): pods is forbidden: User cannot list resource "pods" in API group "" at the cluster scope

Next steps

• Azure role-based access control (Azure RBAC)