How to create nginx ingress rules for services in 3 different namespaces in azure Kubernetes cluster

Question

I have 3 services in 3 different namespaces I want my ingress rules to map to these backends, on path based routes. Can someone please guide on the same. I am using nginx ingress inside azure Kubernetes cluster.

Answer 1

A basic example with an assumption that your nginx ingress is working correctly inside your AKS would be following:

List of Pods with their Services:

Pod	Namespace	Service name
nginx	alpha	alpha-nginx
nginx	beta	beta-nginx
nginx	omega	omega-nginx

---

Ingress definition for this particular setup:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: alpha-ingress
  namespace: alpha
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /$2
spec:
  ingressClassName: nginx
  rules:
  - host: "kubernetes.kruk.lan" 
    http:
      paths:
      - path: /alpha(/|$)(.*)
        pathType: Prefix
        backend:
          service:
            name: alpha-nginx
            port:
              number: 80
--- 
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: beta-ingress
  namespace: beta
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /$2
spec:
  ingressClassName: nginx
  rules:
  - host: "kubernetes.kruk.lan" 
    http:
      paths:
      - path: /beta(/|$)(.*)
        pathType: Prefix
        backend:
          service:
            name: beta-nginx
            port:
              number: 80
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: omega-ingress
  namespace: omega
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /$2
spec:
  ingressClassName: nginx
  rules:
  - host: "kubernetes.kruk.lan" 
    http:
      paths:
      - path: /omega(/|$)(.*)
        pathType: Prefix
        backend:
          service:
            name: omega-nginx
            port:
              number: 80

In this example Ingress will analyze and rewrite the requests for the same domain name to send the traffic to different namespaces i.e. alpha, beta, omega.

When you've have finalized your Ingress resource, you can use curl to validate your configuration.

curl kubernetes.kruk.lan/alpha | grep -i "<h1>"                                    
<h1>Welcome to nginx from ALPHA namespace!</h1>

curl kubernetes.kruk.lan/beta | grep -i "<h1>"                                    
<h1>Welcome to nginx from BETA namespace!</h1>

curl kubernetes.kruk.lan/omega | grep -i "<h1>"                                    
<h1>Welcome to nginx from OMEGA namespace!</h1>

I'd encourage you to check following docs on rewrites:

• Kubernetes.github.io: Ingress-nginx: Examples: Rewrite

---

PS: Pods are default nginx containers/images with added text to /usr/share/nginx/html/index.html