Ingress configuration for k8s in different namespaces

Question

I need to configure Ingress Nginx on azure k8s, and my question is if is possible to have ingress configured in one namespace et. ingress-nginx and some serivces in other na

Answer 1

It's possible actually, you can define ingress and a service with ExternalName type in namespace A, while the ExternalName points to DNS of the service in namespace B. For further details, please refer to this answer: https://stackoverflow.com/a/51899301/2995449

Answer 2

I would like to simplify the answer a bit further for those who are reletively new to Kubernetes and its ingress options in particular. There are 2 separate things that need to be present for ingress to work:

1. Ingress Controller(essentially a separate Pod/Deployment along with a Service that can be used to utilize routing and proxying. Based on nginx container for example);
2. Ingress rules(a separate Kubernetes resourse with kind: Ingress. Will only take effect if Ingress Controller is already deployed)

Now, Ingress Controller can be deployed in any namespace and is, in fact, usually deployed in a namespace separate from your app services. It can out-of-the-box see Ingress rules in all namespaces in the cluster and will pick them up.
The Ingress rules, however, must reside in the namespace where the app that they configure reside.

There are some workarounds for that, but this is the most common approach.

Answer 3

Instead of creating the ingress app-ingress in ingress-nginx namespace you should create it in the namespace where you have the service api-sandand the pod.

Alternatively there is way to achieve ingress in one namespace and service in another namespace via externalName.Checkout Kubernetes Cross Namespace Ingress Network

Here is an example referred from here.

kind: Service
apiVersion: v1
metadata:
  name: my-service
spec:
  type: ExternalName
  externalName: test-service.namespacename.svc.cluster.local

---

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: example-ingress
  annotations:
    kubernetes.io/ingress.class: "nginx"
spec:
  rules:
  - host: example.com
    http:
      paths:
      - path: /
        backend:
          serviceName: my-service
          servicePort: 80