Multiple Nginx Ingress controller in same namespace?

It’s not clear from your post if you intend to deploy multiple nginx-ingress controllers or different ingress controllers. However, both can be deployed in the same namespace.

In the case of deploying different ingress controllers, it should be easy enough to deploy in the same namespace and use class annotations to specify which ingress rule is processed by which Ingress-controller.
However, in case you want to deploy multiple nginx-ingress-controllers in the same namespace, you would have to use update the name/labels or other identifiers to something different.

E.g – The link you mentioned, https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v0.47.0/deploy/static/provider/cloud/deploy.yaml
, would need to be updated as –

apiVersion: v1
kind: ServiceAccount
metadata:
  labels:
    helm.sh/chart: ingress-nginx-3.33.0
    app.kubernetes.io/name: ingress-nginx-internal
    app.kubernetes.io/instance: ingress-nginx-internal
    app.kubernetes.io/version: 0.47.0
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/component: controller
  name: ingress-nginx-internal
  namespace: ingress-nginx
automountServiceAccountToken: true

assuming we call the 2nd nginx-ingress-controller as ingress-nginx-internal; Likewise, all resources created in your link need to be modified and to deploy them in the same namespace.

In addition, you would have to update the deployment args to specify the ingress.class, your controllers would target –

spec:
  template:
     spec:
       containers:
         - name: nginx-ingress-internal-controller
           args:
             - /nginx-ingress-controller
             - '--ingress-class=nginx-internal'
             - '--configmap=ingress/nginx-ingress-internal-controller'

The link https://kubernetes.github.io/ingress-nginx/user-guide/multiple-ingress/ explains how to control multiple ingress controllers.