Advanced Ingress configurations with the application routing add-on

An Ingress is an API object that defines rules, which allow external access to services in an Azure Kubernetes Service (AKS) cluster. When you create an Ingress object that uses the application routing add-on nginx Ingress classes, the add-on creates, configures, and manages one or more Ingress controllers in your AKS cluster.

This article shows you how to set up an advanced Ingress configuration to encrypt the traffic and use Azure DNS to manage DNS zones.

The application routing add-on with nginx delivers the following:

• Easy configuration of managed nginx Ingress controllers based on [Kubernetes nginx Ingress controller][kubernetes-nginx-ingress].
• Integration with an external DNS such as Azure DNS for public and private zone management
• SSL termination with certificates stored in a key vault, such as Azure Key Vault.

• An AKS cluster with the application routing add-on.
• Azure Key Vault if you want to configure SSL termination and store certificates in the vault hosted in Azure.
• Azure DNS if you want to configure public and private zone management and host them in Azure.

To connect to the Kubernetes cluster from your local computer, you use kubectl, the Kubernetes command-line client. You can install it locally using the az aks install-cli command.

Configure kubectl to connect to your Kubernetes cluster using the az aks get-credentials command.

az aks get-credentials -g <ResourceGroupName> -n <ClusterName>

To enable support for HTTPS traffic, see the following prerequisites:

• azure-keyvault-secrets-provider: The Secret Store CSI provider for Azure Key Vault is required to retrieve the certificates from Azure Key Vault.

  Important

  To enable the add-on to reload certificates from Azure Key Vault when they change, you should to enable the secret autorotation feature of the Secret Store CSI driver with the --enable-secret-rotation argument. When autorotation is enabled, the driver updates the pod mount and the Kubernetes secret by polling for changes periodically, based on the rotation poll interval you define. The default rotation poll interval is two minutes.

• An SSL certificate. If you don't have one, you can create a certificate.

To enable application routing on your cluster, use the az aks enable-addons command specifying azure-keyvault-secrets-provider with the --addons argument and the --enable-secret-rotation argument.

az aks enable-addons -g <ResourceGroupName> -n <ClusterName> --addons azure-keyvault-secrets-provider --enable-secret-rotation

Create an Azure Key Vault using the az keyvault create command.

az keyvault create -g <ResourceGroupName> -l <Location> -n <KeyVaultName>

1. Create a self-signed SSL certificate to use with the Ingress using the openssl req command. Make sure you replace <Hostname> with the DNS name you're using.

   openssl req -new -x509 -nodes -out aks-ingress-tls.crt -keyout aks-ingress-tls.key -subj "/CN=<Hostname>" -addext "subjectAltName=DNS:<Hostname>"
   

2. Export the SSL certificate and skip the password prompt using the openssl pkcs12 -export command.

   openssl pkcs12 -export -in aks-ingress-tls.crt -inkey aks-ingress-tls.key -out aks-ingress-tls.pfx
   

Import the SSL certificate into Azure Key Vault using the az keyvault certificate import command. If your certificate is password protected, you can pass the password through the --password flag.

az keyvault certificate import --vault-name <KeyVaultName> -n <KeyVaultCertificateName> -f aks-ingress-tls.pfx [--password <certificate password if specified>]

You use the managed identity in the next steps to grant permissions to manage the Azure DNS zone and retrieve secrets and certificates from the Azure Key Vault.

Get the add-on's managed identity object ID using the az aks show command and setting the output to a variable named MANAGEDIDENTITY_OBJECTID.

# Provide values for your environment
RGNAME=<ResourceGroupName>
CLUSTERNAME=<ClusterName>
MANAGEDIDENTITY_OBJECTID=$(az aks show -g ${RGNAME} -n ${CLUSTERNAME} --query ingressProfile.webAppRouting.identity.objectId -o tsv)

The application routing add-on creates a user-created managed identity in the cluster resource group. You need to grant permissions to the managed identity so it can retrieve SSL certificates from the Azure Key Vault.

Azure Key Vault offers two authorization systems: Azure role-based access control (Azure RBAC), which operates on the management plane, and the access policy model, which operates on both the management plane and the data plane. To find out which system your key vault is using, you can query the enableRbacAuthorization property.

az keyvault show --name <KeyVaultName> --query properties.enableRbacAuthorization

If Azure RBAC authorization is enabled for your key vault, you should configure permissions using Azure RBAC. Add the Key Vault Secrets User role assignment to the key vault by running the following commands.

KEYVAULTID=$(az keyvault show --name <KeyVaultName> --query "id" --output tsv)
az role assignment create --role "Key Vault Secrets User" --assignee $MANAGEDIDENTITY_OBJECTID --scope $KEYVAULTID

If Azure RBAC authorization isn't enabled for your key vault, you should configure permissions using the access policy model. Grant GET permissions for the application routing add-on to retrieve certificates from Azure Key Vault using the az keyvault set-policy command.

az keyvault set-policy --name <KeyVaultName> --object-id $MANAGEDIDENTITY_OBJECTID --secret-permissions get --certificate-permissions get

To enable support for DNS zones, see the following prerequisites:

• The app routing add-on can be configured to automatically create records on one or more Azure public and private DNS zones for hosts defined on Ingress resources. All global Azure DNS zones need to be in the same resource group, and all private Azure DNS zones need to be in the same resource group. If you don't have an Azure DNS zone, you can create one.

  Note

  If you plan to use Azure DNS, you need to update the add-on to include the --dns-zone-resource-ids argument. You can pass a comma separated list of multiple public or private Azure DNS zone resource IDs.

1. Create an Azure DNS zone using the az network dns zone create command.

   az network dns zone create -g <ResourceGroupName> -n <ZoneName>
   

2. Retrieve the resource ID for the DNS zone using the az network dns zone show command and set the output to a variable named ZONEID.

   ZONEID=$(az network dns zone show -g <ResourceGroupName> -n <ZoneName> --query "id" --output tsv)
   

3. Grant DNS Zone Contributor permissions on the DNS zone using the az role assignment create command.

   az role assignment create --role "DNS Zone Contributor" --assignee $MANAGEDIDENTITY_OBJECTID --scope $ZONEID
   

4. Update the add-on to enable the integration with Azure DNS and install the external-dns controller using the az aks addon update command.

   az aks addon update -g <ResourceGroupName> -n <ClusterName> --addon web_application_routing --dns-zone-resource-ids=$ZONEID
   

The application routing add-on creates an Ingress class on the cluster named webapprouting.kubernetes.azure.com. When you create an Ingress object with this class, it activates the add-on.

1. Get the certificate URI to use in the Ingress from Azure Key Vault using the az keyvault certificate show command.

   az keyvault certificate show --vault-name <KeyVaultName> -n <KeyVaultCertificateName> --query "id" --output tsv
   

2. Copy the following YAML manifest into a new file named ingress.yaml and save the file to your local computer.

   Note

   Update <Hostname> with your DNS host name and <KeyVaultCertificateUri> with the ID returned from Azure Key Vault. The secretName key in the tls section defines the name of the secret that contains the certificate for this Ingress resource. This certificate will be presented in the browser when a client browses to the URL defined in the <Hostname> key. Make sure that the value of secretName is equal to keyvault- followed by the value of the Ingress resource name (from metadata.name). In the example YAML, secretName will need to be equal to keyvault-<your Ingress name>.

   apiVersion: networking.k8s.io/v1
   kind: Ingress
   metadata:
     annotations:
       kubernetes.azure.com/tls-cert-keyvault-uri: <KeyVaultCertificateUri>
     name: aks-helloworld
     namespace: hello-web-app-routing
   spec:
     ingressClassName: webapprouting.kubernetes.azure.com
     rules:
    - host: <Hostname>
       http:
         paths:
         - backend:
             service:
               name: aks-helloworld
               port:
                 number: 80
           path: /
           pathType: Prefix
     tls:
    - hosts:
       - <Hostname>
       secretName: keyvault-<your ingress name>
   

3. Create the cluster resources using the kubectl apply command.

   kubectl apply -f ingress.yaml -n hello-web-app-routing
   

   The following example output shows the created resource:

   Ingress.networking.k8s.io/aks-helloworld created
   

You can verify the managed Ingress was created using the kubectl get ingress command.

kubectl get ingress -n hello-web-app-routing

The following example output shows the created managed Ingress:

NAME             CLASS                                HOSTS               ADDRESS       PORTS     AGE
aks-helloworld   webapprouting.kubernetes.azure.com   myapp.contoso.com   20.51.92.19   80, 443   4m