Troubleshooting installing a simple application

Troubleshooting: Installing a simple application

NOTE: Application Gateway for Containers has been released, which introduces numerous performance, resilience, and feature changes. Please consider leveraging Application Gateway for Containers for your next deployment.

Azure Cloud Shell is the most convenient way to troubleshoot any problems with your AKS and AGIC installation. Launch your shell from shell.azure.com or by clicking the link:

In the troubleshooting document, we will debug issues in the AGIC installation by installing a simple application step by step and check the output as we go along. The steps below assume:

You have an AKS cluster, with Advanced Networking enabled
AGIC has been installed on the AKS cluster
You already hav an App Gateway on a VNET shared with your AKS cluster

To verify that the App Gateway + AKS + AGIC installation is setup correctly, deploy the simplest possible app:

cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
  name: test-agic-app-pod
  labels:
    app: test-agic-app
spec:
  containers:
  - image: "mcr.microsoft.com/dotnet/samples:aspnetapp"
    name: aspnetapp-image
    ports:
    - containerPort: 80
      protocol: TCP
---
apiVersion: v1
kind: Service
metadata:
  name: test-agic-app-service
spec:
  selector:
    app: test-agic-app
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: test-agic-app-ingress
  annotations:
    kubernetes.io/ingress.class: azure/application-gateway
spec:
  rules:
    - host: test.agic.contoso.com
      http:
        paths:
          - path: /
            backend:
              service:
                name: test-agic-app-service
                port:
                  number: 80
            pathType: Exact
EOF

Copy and paste all lines at once from the script above into a Azure Cloud Shell. Please ensure the entire command is copied - starting with cat and including the last EOF.

apply

After a successful deployment of the app above your AKS cluster will have a new Pod, Service and an Ingress.

Get the list of pods with Cloud Shell: kubectl get pods -o wide. We expect for a pod named 'test-agic-app-pod' to have been created. It will have an IP address. This address must be within the VNET of the App Gateway, which is used with AKS.

pods

Get the list of services: kubectl get services -o wide. We expect to see a service named 'test-agic-app-service'.

pods

Get the list of the ingresses: kubectl get ingress. We expect an Ingress resource named 'test-agic-app-ingress' to have been created. The resource will have a host name 'test.agic.contoso.com'.

pods

One of the pods will be AGIC. kubectl get pods will show a list of pods, one of which will begin with 'ingress-azure'. Get all logs of that pod with kubectl logs <name-of-ingress-controller-pod> to verify that we have had a successful deployment. A successful deployment would have added the following lines to the log:

I0927 22:34:51.281437       1 process.go:156] Applied App Gateway config in 20.461335266s
I0927 22:34:51.281585       1 process.go:165] cache: Updated with latest applied config.
I0927 22:34:51.282342       1 process.go:171] END AppGateway deployment

Alternatively, from Cloud Shell we can retrieve only the lines indicating successful App Gateway configuration with kubectl logs <ingress-azure-....> | grep 'Applied App Gateway config in', where <ingress-azure....> should be the exact name of the AGIC pod.

App Gateway will have the following configuration applied:

Listener:
Routing Rule:
Backend Pool:
There will be one IP address in the backend address pool and it will match the IP address of the Pod we observed earlier with kubectl get pods -o wide

Finally we can use the cURL command from within Cloud Shell to establish an HTTP connection to the newly deployed app:

Use kubectl get ingress to get the Public IP address of App Gateway
Use curl -I -H 'Host: test.agic.contoso.com' <publitc-ip-address-from-previous-command>

pods

A result of HTTP/1.1 200 OK indicates that the App Gateway + AKS + AGIC system is working as expected.

Inspect Kubernetes Installation

Pods, Services, Ingress

Application Gateway Ingress Controller (AGIC) continuously monitors the following Kubernetes resources: Deployment or Pod, Service, Ingress

The following must be in place for AGIC to function as expected:

AKS must have one or more healthy pods. Verify this from Cloud Shell with kubectl get pods -o wide --show-labels If you have a Pod with an aspnetapp, your output may look like this:

$> kubectl get pods -o wide --show-labels

NAME                   READY   STATUS    RESTARTS   AGE   IP          NODE                       NOMINATED NODE   READINESS GATES   LABELS
aspnetapp              1/1     Running   0          17h   10.0.0.6    aks-agentpool-35064155-1   <none>           <none>            app=aspnetapp

One or more services, referencing the pods above via matching selector labels. Verify this from Cloud Shell with kubectl get services -o wide

$> kubectl get services -o wide --show-labels

NAME                TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)   AGE   SELECTOR        LABELS
aspnetapp           ClusterIP   10.2.63.254    <none>        80/TCP    17h   app=aspnetapp   <none>

Ingress, annotated with kubernetes.io/ingress.class: azure/application-gateway, referencing the service above Verify this from Cloud Shell with kubectl get ingress -o wide --show-labels

$> kubectl get ingress -o wide --show-labels

NAME        HOSTS   ADDRESS   PORTS   AGE   LABELS
aspnetapp   *                 80      17h   <none>

View annotations of the ingress above: kubectl get ingress aspnetapp -o yaml (substitute aspnetapp with the name of your ingress)

$> kubectl get ingress aspnetapp -o yaml

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  annotations:
    kubernetes.io/ingress.class: azure/application-gateway
  name: aspnetapp
spec:
  defaultBackend:
    service:
     name: aspnetapp
     port:
       number: 80

The ingress resource must be annotated with kubernetes.io/ingress.class: azure/application-gateway.

Verify Observed Nampespace

Get the existing namespaces in Kubernetes cluster. What namespace is your app running in? Is AGIC watching that namespace? Refer to the Multiple Namespace Support documentation on how to properly configure observed namespaces.
```
# What namespaces exist on your cluster
kubectl get namespaces

# What pods are currently running
kubectl get pods --all-namespaces -o wide
```
The AGIC pod should be in the default namespace (see column NAMESPACE). A healthy pod would have Running in the STATUS column. There should be at least one AGIC pod.
```
# Get a list of the Application Gateway Ingress Controller pods
kubectl get pods --all-namespaces --selector app=ingress-azure
```
If the AGIC pod is not healthy (STATUS column from the command above is not Running):
get logs to understand why: kubectl logs <pod-name>
for the previous instance of the pod: kubectl logs <pod-name> --previous
describe the pod to get more context: kubectl describe pod <pod-name>

Do you have a Kubernetes Service and Ingress resources?

# Get all services across all namespaces
kubectl get service --all-namespaces -o wide

# Get all ingress resources across all namespaces
kubectl get ingress --all-namespaces -o wide

Is your Ingress annotated with: kubernetes.io/ingress.class: azure/application-gateway? AGIC will only watch for Kubernetes Ingress resources that have this annotation.
```
# Get the YAML definition of a particular ingress resource
kubectl get ingress --namespace  <which-namespace?>  <which-ingress?>  -o yaml
```
AGIC emits Kubernetes events for certain critical errors. You can view these:
in your terminal via kubectl get events --sort-by=.metadata.creationTimestamp
in your browser using the Kubernetes Web UI (Dashboard)