Search code examples
kubernetesdnsibm-cloudkubernetes-ingressnginx-ingress

Kubernetes Ingress not forwarding routes

I am fairly new to Kubernetes and have just deployed my first cluster to IBM Cloud. When I created the cluster, I get a dedicated ingress subdomain, which I will be referring to as <long-k8subdomain>.cloud for the scope of this post. Now, this subdomain works for my app. For example: <long-k8subdomain>.cloud/ping works from my browser/curl just fine- I get the expected JSON response back. But, if I add this subdomain to a CNAME record on my domain provider's DNS settings (I have used Bluehost and IBM Cloud's Internet Services), I get a 404 response back from all routes. However this response is the default nginx 404 response (it says "nginx" under "404 Not Found"). I believe this means that this means the ingress load balancer is being reached, but the request does not get routed right. I am using Kubernetes version 1.20.12_1561 on VPC gen 2 and this is my ingress-config.yaml file:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: my-ingress-resource
  annotations:
    kubernetes.io/ingress.class: "public-iks-k8s-nginx"
    nginx.ingress.kubernetes.io/configuration-snippet: |
      more_set_headers "Host: <long-k8subdomain>.cloud";
spec:
  rules:
  - host: <long-k8subdomain>.cloud
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: my-service-name
            port:
              number: 80

I am pretty sure this problem is due to the annotations. Maybe I am using the wrong ones or I do not have enough. Ideally, I would like something like this: api..com/ to route correctly. I have also read a little bit about default backends, but I have not dove too much into that just yet. Any help would be greatly appreciated, as I have spent multiple hours trying to fix this.

Some sources I have used:

Note: The reason why I have the second annotation is because for some reason, requests without that header were not being routed directly. So that was part of my debugging process and I just ended up leaving it as I am not sure if that annotation solves that, so I left it for now.

Solution

  • For the NGINX ingress controller to route requests for your own domain's CNAME record to the service instead of the IBM Cloud one, you need a rule in the ingress where the host identifies your domain.

    For instance, if your domain's DNS entry is api.example.com, then change the resource YAML to:

    apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: my-ingress-resource
  annotations:
    kubernetes.io/ingress.class: "public-iks-k8s-nginx"
spec:
  rules:
  - host: api.example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: my-service-name
            port:
              number: 80

    You should not need the second annotation for this to work.

    If you want both of the hosts to work, then you could add a second rule instead of replacing host in the existing one.