nginx-ingress not forwarding to dashboard

It seems to me that you've used wrong location path /dashboard within yours origin Ingress configuration, even more the relevant K8s dashboard UI endpoint is exposed on 443 port by default across the corresponded K8s Service resource, whenever you've not customized this setting.

ports:- port: 443  protocol: TCP  targetPort: 8443

In order to get a proper path based routing, override existing parameters with the following arguments:

paths:- path: /  backend:    serviceName: kubernetes-dashboard    servicePort: 443

Once you've decided accessing K8s dashboard UI through indirect path holder URL (https://abc.def.com/dashboard), you can manage applying Rewrite rules in order to transparently change a part of the authentic URL and transmit requests to the faithful target path. Actually, Nginx Ingress controller adds this functionality via specific nginx.ingress.kubernetes.io/rewrite-target annotation:

apiVersion: extensions/v1beta1kind: Ingressmetadata:  name: dashboard  annotations:    nginx.ingress.kubernetes.io/backend-protocol: "HTTPS"    nginx.ingress.kubernetes.io/force-ssl-redirect: "false"    nginx.ingress.kubernetes.io/rewrite-target: /$2  namespace: kube-systemspec:#  tls:#  - hosts:#    - abc.def.com  rules:  - host: abc.def.com    http:      paths:      - path: /dashboard(/|$)(.*)        backend:          serviceName: kubernetes-dashboard          servicePort: 443

This can happen if your cluster doesn't have nginx as the default ingress class, and your ingress manifest doesn't specify one.

You can try one of the following:- Upgrade your NGINX-ingress installation with controller.ingressClass set to nginx (with this, all ingresses created will use NGINX-ingress by default)- Add the kubernetes.io/ingress.class: nginx annotation to your ingress yaml to specify that you want NGINX-ingress to handle it.