kubernetes kubernetes-ingress nginx-ingress kubeadm

Nginx Ingress Controller - Failed Calling Webhook

I set up a k8s cluster using kubeadm (v1.18) on an Ubuntu virtual machine. Now I need to add an Ingress Controller. I decided for nginx (but I'm open for other solutions). I installed it according to the docs, section "bare-metal":

kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-0.31.1/deploy/static/provider/baremetal/deploy.yaml

The installation seems fine to me:

kubectl get all -n ingress-nginx

NAME                                            READY   STATUS      RESTARTS   AGE
pod/ingress-nginx-admission-create-b8smg        0/1     Completed   0          8m21s
pod/ingress-nginx-admission-patch-6nbjb         0/1     Completed   1          8m21s
pod/ingress-nginx-controller-78f6c57f64-m89n8   1/1     Running     0          8m31s

NAME                                         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)                      AGE
service/ingress-nginx-controller             NodePort    10.107.152.204   <none>        80:32367/TCP,443:31480/TCP   8m31s
service/ingress-nginx-controller-admission   ClusterIP   10.110.191.169   <none>        443/TCP                      8m31s

NAME                                       READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/ingress-nginx-controller   1/1     1            1           8m31s

NAME                                                  DESIRED   CURRENT   READY   AGE
replicaset.apps/ingress-nginx-controller-78f6c57f64   1         1         1       8m31s

NAME                                       COMPLETIONS   DURATION   AGE
job.batch/ingress-nginx-admission-create   1/1           2s         8m31s
job.batch/ingress-nginx-admission-patch    1/1           3s         8m31s

However, when trying to apply a custom Ingress, I get the following error:

Error from server (InternalError): error when creating "yaml/xxx/xxx-ingress.yaml": Internal error occurred: failed calling webhook "validate.nginx.ingress.kubernetes.io": Post https://ingress-nginx-controller-admission.ingress-nginx.svc:443/extensions/v1beta1/ingresses?timeout=30s: Temporary Redirect

Any idea what could be wrong?

I suspected DNS, but other NodePort services are working as expected and DNS works within the cluster.

The only thing I can see is that I don't have a default-http-backend which is mentioned in the docs here. However, this seems normal in my case, according to this thread.

Last but not least, I tried as well the installation with manifests (after removing ingress-nginx namespace from previous installation) and the installation via Helm chart. It has the same result.

I'm pretty much a beginner on k8s and this is my playground-cluster. So I'm open to alternative solutions as well, as long as I don't need to set up the whole cluster from scratch.

Update: With "applying custom Ingress", I mean: kubectl apply -f <myIngress.yaml>

Content of myIngress.yaml

apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: my-ingress
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  rules:
  - http:
      paths:
      - path: /someroute/fittingmyneeds
        pathType: Prefix
        backend:
          serviceName: some-service
          servicePort: 5000

Solution

I am not sure if this helps this late, but might it be, that your cluster was behind proxy? Because in that case you have to have no_proxy configured correctly. Specifically, it has to include .svc,.cluster.local otherwise validation webhook requests such as https://ingress-nginx-controller-admission.ingress-nginx.svc:443/extensions/v1beta1/ingresses?timeout=30s will be routed via proxy server (note that .svc in the URL).

I had exactly this issue and adding .svc into no_proxy variable helped. You can try this out quickly by modifying /etc/kubernetes/manifests/kube-apiserver.yaml file which will in turn automatically recreate your kubernetes api server pod.

This is not the case just for ingress validation, but also for other things that might refer URL in your cluster ending with .svc or .namespace.svc.cluster.local (i.e. see this bug)