HTTP application routing add-on for Azure Kubernetes Service (AKS) (retired)

Άρθρο
04/05/2023

Caution

HTTP application routing add-on (preview) for Azure Kubernetes Service (AKS) will be retired on 03 March 2025. We recommend migrating to the Application Routing add-on by that date.

The HTTP application routing add-on makes it easy to access applications that are deployed to your Azure Kubernetes Service (AKS) cluster by:

Configuring an ingress controller in your AKS cluster.
Creating publicly accessible DNS names for application endpoints
Creating a DNS zone in your subscription. For more information about DNS cost, see DNS pricing.

Before you begin

The HTTP application routing add-on doesn't work with AKS versions 1.22.6+.
If you're running commands locally, install kubectl using the az aks install-cli command.

HTTP application routing add-on overview

The add-on deploys two components: a Kubernetes ingress controller and an External-DNS controller.

Ingress controller: The ingress controller is exposed to the internet using a Kubernetes LoadBalancer service. The ingress controller watches and implements Kubernetes ingress resources and creates routes to application endpoints.
External-DNS controller: The External-DNS controller watches for Kubernetes ingress resources and creates DNS A records in the cluster-specific DNS zone.

Enable HTTP application routing

Create a new AKS cluster and enable the HTTP application routing add-on using the az aks create command with the --enable-addons parameter.

az aks create \
    --resource-group myResourceGroup \
    --name myAKSCluster \
    --enable-addons http_application_routing \
    --generate-ssh-keys

You can also enable HTTP routing on an existing AKS cluster using the az aks enable-addons command with the --addons parameter.

az aks enable-addons --resource-group myResourceGroup --name myAKSCluster --addons http_application_routing

Retrieve the DNS zone name using the az aks show command. You need the DNS zone name to deploy applications to the cluster.

az aks show --resource-group myResourceGroup --name myAKSCluster --query addonProfiles.httpApplicationRouting.config.HTTPApplicationRoutingZoneName -o table

Your output should look like the following example output:

9f9c1fe7-21a1-416d-99cd-3543bb92e4c3.eastus.aksapp.io

Connect to your AKS cluster

Configure kubectl to connect to your Kubernetes cluster using the az aks get-credentials command. The following example gets credentials for the AKS cluster named myAKSCluster in the myResourceGroup:
```
az aks get-credentials --resource-group myResourceGroup --name myAKSCluster
```

Use HTTP application routing

Important

The HTTP application routing add-on can only be triggered on ingress resources with the following annotation:

annotations:
 kubernetes.io/ingress.class: addon-http-application-routing

Create a file named samples-http-application-routing.yaml and copy in the following YAML. On line 43, update <CLUSTER_SPECIFIC_DNS_ZONE> with the DNS zone name you collected in the previous step.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: aks-helloworld
spec:
  replicas: 1
  selector:
    matchLabels:
      app: aks-helloworld
  template:
    metadata:
      labels:
        app: aks-helloworld
    spec:
      containers:
      - name: aks-helloworld
        image: mcr.microsoft.com/azuredocs/aks-helloworld:v1
        ports:
        - containerPort: 80
        env:
        - name: TITLE
          value: "Welcome to Azure Kubernetes Service (AKS)"
---
apiVersion: v1
kind: Service
metadata:
  name: aks-helloworld
spec:
  type: ClusterIP
  ports:
 - port: 80
  selector:
    app: aks-helloworld
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: aks-helloworld
  annotations:
    kubernetes.io/ingress.class: addon-http-application-routing
spec:
  rules:
 - host: aks-helloworld.<CLUSTER_SPECIFIC_DNS_ZONE>
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: aks-helloworld
            port:
              number: 80

Create the resources using the kubectl apply command.

kubectl apply -f samples-http-application-routing.yaml

The following example shows the created resources:

deployment.apps/aks-helloworld created
service/aks-helloworld created
ingress.networking.k8s.io/aks-helloworld created

Open a web browser to aks-helloworld.<CLUSTER_SPECIFIC_DNS_ZONE>, for example aks-helloworld.9f9c1fe7-21a1-416d-99cd-3543bb92e4c3.eastus.aksapp.io and verify you see the demo application. The application may take a few minutes to appear.

Remove HTTP application routing

Remove the HTTP application routing add-on using the [az aks disable-addons][az-aks-disable-addons] command with the addons` parameter.
```
az aks disable-addons --addons http_application_routing --name myAKSCluster --resource-group myResourceGroup --no-wait
```

When the HTTP application routing add-on is disabled, some Kubernetes resources may remain in the cluster. These resources include configmaps and secrets and are created in the kube-system namespace. To maintain a clean cluster, you may want to remove these resources. Look for addon-http-application-routing resources using the following kubectl get commands:

kubectl get deployments --namespace kube-system
kubectl get services --namespace kube-system
kubectl get configmaps --namespace kube-system
kubectl get secrets --namespace kube-system

The following example output shows configmaps that should be deleted:

NAMESPACE     NAME                                                       DATA   AGE
kube-system   addon-http-application-routing-nginx-configuration         0      9m7s
kube-system   addon-http-application-routing-tcp-services                0      9m7s
kube-system   addon-http-application-routing-udp-services                0      9m7s

Delete remaining resources using the kubectl delete command. Make sure to specify the resource type, resource name, and namespace. The following example deletes one of the previous configmaps:
```
kubectl delete configmaps addon-http-application-routing-nginx-configuration --namespace kube-system
```
Repeat the previous kubectl delete step for all addon-http-application-routing resources remaining in your cluster.

Troubleshoot

View the application logs for the External-DNS application using the kubectl logs command.

kubectl logs -f deploy/addon-http-application-routing-external-dns -n kube-system

The logs should confirm that an A and TXT DNS record were created successfully, as shown in the following example output:

time="2018-04-26T20:36:19Z" level=info msg="Updating A record named 'aks-helloworld' to '52.242.28.189' for Azure DNS zone '471756a6-e744-4aa0-aa01-89c4d162a7a7.canadaeast.aksapp.io'."
time="2018-04-26T20:36:21Z" level=info msg="Updating TXT record named 'aks-helloworld' to '"heritage=external-dns,external-dns/owner=default"' for Azure DNS zone '471756a6-e744-4aa0-aa01-89c4d162a7a7.canadaeast.aksapp.io'."

View the application logs for the NGINX ingress controller using the kubectl logs command.

kubectl logs -f deploy/addon-http-application-routing-nginx-ingress-controller -n kube-system

The logs should confirm the CREATE of an ingress resource and the reload of the controller, as shown in the following example output:

-------------------------------------------------------------------------------
NGINX Ingress controller
  Release:    0.13.0
  Build:      git-4bc943a
  Repository: https://github.com/kubernetes/ingress-nginx
-------------------------------------------------------------------------------

I0426 20:30:12.212936       9 flags.go:162] Watching for ingress class: addon-http-application-routing
W0426 20:30:12.213041       9 flags.go:165] only Ingress with class "addon-http-application-routing" will be processed by this ingress controller
W0426 20:30:12.213505       9 client_config.go:533] Neither --kubeconfig nor --master was specified.  Using the inClusterConfig.  This might not work.
I0426 20:30:12.213752       9 main.go:181] Creating API client for https://10.0.0.1:443
I0426 20:30:12.287928       9 main.go:225] Running in Kubernetes Cluster version v1.8 (v1.8.11) - git (clean) commit 1df6a8381669a6c753f79cb31ca2e3d57ee7c8a3 - platform linux/amd64
I0426 20:30:12.290988       9 main.go:84] validated kube-system/addon-http-application-routing-default-http-backend as the default backend
I0426 20:30:12.294314       9 main.go:105] service kube-system/addon-http-application-routing-nginx-ingress validated as source of Ingress status
I0426 20:30:12.426443       9 stat_collector.go:77] starting new nginx stats collector for Ingress controller running in namespace  (class addon-http-application-routing)
I0426 20:30:12.426509       9 stat_collector.go:78] collector extracting information from port 18080
I0426 20:30:12.448779       9 nginx.go:281] starting Ingress controller
I0426 20:30:12.463585       9 event.go:218] Event(v1.ObjectReference{Kind:"ConfigMap", Namespace:"kube-system", Name:"addon-http-application-routing-nginx-configuration", UID:"2588536c-4990-11e8-a5e1-0a58ac1f0ef2", APIVersion:"v1", ResourceVersion:"559", FieldPath:""}): type: 'Normal' reason: 'CREATE' ConfigMap kube-system/addon-http-application-routing-nginx-configuration
I0426 20:30:12.466945       9 event.go:218] Event(v1.ObjectReference{Kind:"ConfigMap", Namespace:"kube-system", Name:"addon-http-application-routing-tcp-services", UID:"258ca065-4990-11e8-a5e1-0a58ac1f0ef2", APIVersion:"v1", ResourceVersion:"561", FieldPath:""}): type: 'Normal' reason: 'CREATE' ConfigMap kube-system/addon-http-application-routing-tcp-services
I0426 20:30:12.467053       9 event.go:218] Event(v1.ObjectReference{Kind:"ConfigMap", Namespace:"kube-system", Name:"addon-http-application-routing-udp-services", UID:"259023bc-4990-11e8-a5e1-0a58ac1f0ef2", APIVersion:"v1", ResourceVersion:"562", FieldPath:""}): type: 'Normal' reason: 'CREATE' ConfigMap kube-system/addon-http-application-routing-udp-services
I0426 20:30:13.649195       9 nginx.go:302] starting NGINX process...
I0426 20:30:13.649347       9 leaderelection.go:175] attempting to acquire leader lease  kube-system/ingress-controller-leader-addon-http-application-routing...
I0426 20:30:13.649776       9 controller.go:170] backend reload required
I0426 20:30:13.649800       9 stat_collector.go:34] changing prometheus collector from  to default
I0426 20:30:13.662191       9 leaderelection.go:184] successfully acquired lease kube-system/ingress-controller-leader-addon-http-application-routing
I0426 20:30:13.662292       9 status.go:196] new leader elected: addon-http-application-routing-nginx-ingress-controller-5cxntd6
I0426 20:30:13.763362       9 controller.go:179] ingress backend successfully reloaded...
I0426 21:51:55.249327       9 event.go:218] Event(v1.ObjectReference{Kind:"Ingress", Namespace:"default", Name:"aks-helloworld", UID:"092c9599-499c-11e8-a5e1-0a58ac1f0ef2", APIVersion:"extensions", ResourceVersion:"7346", FieldPath:""}): type: 'Normal' reason: 'CREATE' Ingress default/aks-helloworld
W0426 21:51:57.908771       9 controller.go:775] service default/aks-helloworld does not have any active endpoints
I0426 21:51:57.908951       9 controller.go:170] backend reload required
I0426 21:51:58.042932       9 controller.go:179] ingress backend successfully reloaded...
167.220.24.46 - [167.220.24.46] - - [26/Apr/2018:21:53:20 +0000] "GET / HTTP/1.1" 200 234 "" "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)" 197 0.001 [default-aks-helloworld-80] 10.244.0.13:8080 234 0.004 200

Clean up resources

Remove the associated Kubernetes objects created in this article using the kubectl delete command.
```
kubectl delete -f samples-http-application-routing.yaml
```
The following example output shows Kubernetes objects have been removed:
```
deployment "aks-helloworld" deleted
service "aks-helloworld" deleted
ingress "aks-helloworld" deleted
```

Next steps

For information on how to install an HTTPS-secured ingress controller in AKS, see HTTPS ingress on Azure Kubernetes Service (AKS).

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