Set up a custom domain name and SSL certificate with the application routing add-on

Article
08/08/2024

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 with SSL/TLS certificates stored in an Azure Key Vault, and use Azure DNS to manage DNS zones.

Application routing add-on with nginx features

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

Easy configuration of managed nginx Ingress controllers.
Integration with an external DNS such as Azure DNS for global and private zone management
SSL termination with certificates stored in a key vault, such as Azure Key Vault.

Prerequisites

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 global and private zone management and host them in Azure.
To attach an Azure Key Vault or Azure DNS Zone, you need the Owner, Azure account administrator, or Azure co-administrator role on your Azure subscription.
All public DNS Zones must be in the same subscription and Resource Group.

Connect to your AKS cluster

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 --resource-group <ResourceGroupName> --name <ClusterName>

Terminate HTTPS traffic with certificates from Azure Key Vault

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

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

Create an Azure Key Vault to store the certificate

Note

If you already have an Azure Key Vault, you can skip this step.

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

az keyvault create --resource-group <ResourceGroupName> --location <Location> --name <KeyVaultName> --enable-rbac-authorization true

Create and export a self-signed SSL certificate

Note

If you already have a certificate, you can skip this step.

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>"
```

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 certificate into Azure Key Vault

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> --name <KeyVaultCertificateName> --file aks-ingress-tls.pfx [--password <certificate password if specified>]

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.

Enable Azure Key Vault integration

On a cluster with the application routing add-on enabled, use the az aks approuting update command using the --enable-kv and --attach-kv arguments to enable the Azure Key Vault provider for Secrets Store CSI Driver and apply the required role assignments.

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. The --attach-kv operation will choose the appropriate access model to use.

Note

The az aks approuting update --attach-kv command uses the permissions of the user running the command to create the Azure Key Vault role assignment. This role is assigned to the add-on's managed identity. For more information on AKS managed identities, see Summary of managed identities.

Retrieve the Azure Key Vault resource ID.

KEYVAULTID=$(az keyvault show --name <KeyVaultName> --query "id" --output tsv)

Then update the app routing add-on to enable the Azure Key Vault secret store CSI driver and apply the role assignment.

az aks approuting update --resource-group <ResourceGroupName> --name <ClusterName> --enable-kv --attach-kv ${KEYVAULTID}

Enable Azure DNS integration

To enable support for DNS zones, review the following prerequisite:

The app routing add-on can be configured to automatically create records on one or more Azure global 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.

Create a public Azure DNS zone

Note

If you already have an Azure DNS Zone, you can skip this step.

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

az network dns zone create --resource-group <ResourceGroupName> --name <ZoneName>

Attach Azure DNS zone to the application routing add-on

Note

The az aks approuting zone add command uses the permissions of the user running the command to create the Azure DNS Zone role assignment. This role is assigned to the add-on's managed identity. For more information on AKS managed identities, see Summary of managed identities.

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=$(az network dns zone show --resource-group <ResourceGroupName> --name <ZoneName> --query "id" --output tsv)
```
Update the add-on to enable the integration with Azure DNS using the az aks approuting zone command. You can pass a comma-separated list of DNS zone resource IDs.
```
az aks approuting zone add --resource-group <ResourceGroupName> --name <ClusterName> --ids=${ZONEID} --attach-zones
```

Create the Ingress that uses a host name and a certificate from Azure Key Vault

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.

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> --name <KeyVaultCertificateName> --query "id" --output tsv

The following example output shows the certificate URI returned from the command:

https://KeyVaultName.vault.azure.cn/certificates/KeyVaultCertificateName/ea62e42260f04f17a9309d6b87aceb44

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

Update <Hostname> with the name of your DNS host and <KeyVaultCertificateUri> with the URI returned from the command to query Azure Key Vault in step 1 above. The string value for *<KeyVaultCertificateUri>* should only include https://yourkeyvault.vault.azure.cn/certificates/certname. The Certificate Version at the end of the URI string should be omitted in order to get the current version.

The secretName key in the tls section defines the name of the secret that contains the certificate for this Ingress resource. This certificate is presented in the browser when a client browses to the URL specified 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 needs 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>
```
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
```

Verify the managed Ingress was 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

Set up a custom domain name and SSL certificate with the application routing add-on

Application routing add-on with nginx features

Prerequisites

Connect to your AKS cluster

Terminate HTTPS traffic with certificates from Azure Key Vault

Create an Azure Key Vault to store the certificate

Create and export a self-signed SSL certificate

Import certificate into Azure Key Vault

Enable Azure Key Vault integration

Enable Azure DNS integration

Create a public Azure DNS zone

Attach Azure DNS zone to the application routing add-on

Create the Ingress that uses a host name and a certificate from Azure Key Vault

Verify the managed Ingress was created

Additional resources