Configure ARO to use Microsoft Entra ID

This guide demonstrates how to configure Azure AD as the cluster identity provider in Azure Red Hat OpenShift. This guide will walk through the creation of an Azure Active Directory (Azure AD) application and configure Azure Red Hat OpenShift (ARO) to authenticate using Azure AD.

This guide will walk through the following steps:

1. Register a new application in Azure AD for authentication.
2. Configure the application registration in Azure AD to include optional claims in tokens.
3. Configure the Azure Red Hat OpenShift (ARO) cluster to use Azure AD as the identity provider.
4. Grant additional permissions to individual users.

Before you Begin

If you are using zsh as your shell (which is the default shell on macOS) you may need to run set -k to get the below commands to run without errors. This is because zsh disables comments in interactive shells from being used .

1. Register a new application in Azure AD for authentication

Capture the OAuth callback URL

First, construct the cluster’s OAuth callback URL and make note of it. To do so, run the following command, making sure to replace the variables specified:

The “AAD” directory at the end of the the OAuth callback URL should match the OAuth identity provider name you’ll setup later.

RESOURCE_GROUP=example-rg # Replace this with the name of your ARO cluster's resource group
CLUSTER_NAME=example-cluster # Replace this with the name of your ARO cluster
echo 'OAuth callback URL: '$(az aro show -g $RESOURCE_GROUP -n $CLUSTER_NAME --query consoleProfile.url -o tsv | sed 's/console-openshift-console/oauth-openshift/')'oauth2callback/AAD'

Register a new application in Azure AD

Second, you need to create the Azure AD application itself. To do so, login to the Azure portal, and navigate to App registrations blade , then click on “New registration” to create a new application.

Provide a name for the application, for example openshift-auth. Select “Web” from the Redirect URI dropdown and fill in the Redirect URI using the value of the OAuth callback URL you retrieved in the previous step. Once you fill in the necessary information, click “Register” to create the application.

Then, click on the “Certificates & secrets” sub-blade and select “New client secret”. Fill in the details request and make note of the generated client secret value, as you’ll use it in a later step. You won’t be able to retrieve it again.

Then, click on the “Overview” sub-blade and make note of the “Application (client) ID” and “Directory (tenant) ID”. You’ll need those values in a later step as well.

2. Configure optional claims

In order to provide OpenShift with enough information about the user to create their account, we will configure Azure AD to provide two optional claims, specifically “email” and “preferred_username” when a user logs in. For more information on optional claims in Azure AD, see the Microsoft documentation .

Click on the “Token configuration” sub-blade and select the “Add optional claim” button.

Select ID then check the “email” and “preferred_username” claims and click the “Add” button to configure them for your Azure AD application.

When prompted, follow the prompt to enable the necessary Microsoft Graph permissions.

3. Configure the OpenShift cluster to use Azure AD as the identity provider

Finally, we need to configure OpenShift to use Azure AD as its identity provider.

To do so, ensure you are logged in to the OpenShift command line interface (oc) by running the following command, making sure to replace the variables specified:

RESOURCE_GROUP=example-rg # Replace this with the name of your ARO cluster's resource group
CLUSTER_NAME=example-cluster # Replace this with the name of your ARO cluster
oc login \
    $(az aro show -g $RESOURCE_GROUP -n $CLUSTER_NAME --query apiserverProfile.url -o tsv) \
    -u $(az aro list-credentials -g $RESOURCE_GROUP -n $CLUSTER_NAME --query kubeadminUsername -o tsv) \
    -p $(az aro list-credentials -g $RESOURCE_GROUP -n $CLUSTER_NAME --query kubeadminPassword -o tsv)

Next, create a secret that contains the client secret that you captured in step 2 above. To do so, run the following command, making sure to replace the variable specified:

CLIENT_SECRET=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx # Replace this with the Client Secret
oc create secret generic openid-client-secret --from-literal=clientSecret=${CLIENT_SECRET} -n openshift-config

Next, generate the necessary YAML for the cluster’s OAuth provider to use Azure AD as its identity provider. To do so, run the following command, making sure to replace the variables specified:

IDP_NAME=AAD # Replace this with the name you used in the OAuth callback URL
APP_ID=yyyyyyyy-yyyy-yyyy-yyyy-yyyyyyyyyyyy # Replace this with the Application (client) ID
TENANT_ID=zzzzzzzz-zzzz-zzzz-zzzz-zzzzzzzzzzzz # Replace this with the Directory (tenant) ID
cat << EOF > cluster-oauth-config.yaml
apiVersion: config.openshift.io/v1
kind: OAuth
metadata:
  name: cluster
spec:
  identityProviders:
  - mappingMethod: claim
    name: ${IDP_NAME}
    openID:
      claims:
        email:
        - email
        name:
        - name
        preferredUsername:
        - preferred_username
      clientID: ${APP_ID}
      clientSecret:
        name: openid-client-secret
      extraScopes: 
      - profile
      - openid
      - email
      issuer: https://login.microsoftonline.com/${TENANT_ID}/v2.0
    type: OpenID
EOF

Feel free to further modify this output (which is saved in your current directory as cluster-oauth-config.yaml).

Finally, apply the new configuration to the cluster’s OAuth provider by running the following command:

oc apply -f ./cluster-oauth-config.yaml

Note: It is normal to receive an error that says an annotation is missing when you run oc apply for the first time. This can be safely ignored.

Once the cluster authentication operator reconciles your changes (generally within a few minutes), you will be able to login to the cluster using Azure AD.

If you have a private cluster behind a firewall, you may get an error message like the image below when you try login into the web console using the AAD option. In this case you should open a firewall rule allowing access from the cluster to graph.microsoft.com.

If you are using Azure Firewall, you can run those commands to allow this access:

az network firewall network-rule create -g $AZR_RESOURCE_GROUP -f aro-private   \
    --collection-name 'Allow_Microsoft_Graph' --action allow --priority 100     \
    -n 'Microsoft_Graph' --source-address '*' --protocols 'any'                 \
    --source-addresses '*' --destination-fqdns 'graph.microsoft.com'            \
    --destination-ports '*'

Now you should be able to login choosing the AAD option:

Then inform the user you would like to use:

4. Grant additional permissions to individual users

Once you login, you will notice that you have very limited permissions. This is because, by default, OpenShift only grants you the ability to create new projects (namespaces) in the cluster. Other projects (namespaces) are restricted from view.

OpenShift includes a significant number of pre-configured roles, including the cluster-admin role that grants full access and control over the cluster. To grant your user access to the cluster-admin role, you must create a ClusterRoleBinding to your user account.

USERNAME=example@redhat.com # Replace with your Azure AD username
oc create clusterrolebinding cluster-admin-user \
    --clusterrole=cluster-admin \
    --user=$USERNAME

For more information on how to use RBAC to define and apply permissions in OpenShift, see the OpenShift documentation .