Setup Nginx Ingress Controller for cross namespace ingress resources

Pre-requisites

As part of setting this up, I tested this locally using minikube and on Google Kubernetes Engine (GKE)

Setup

Nginx Ingress Controller

We will be installing Nginx Ingress controller as a helm chart from kubernetes/charts/stable/nginx-ingress
Since recent Kubernetes versions have RBAC enabled by default, we will need to install it with RBAC in mind.
- You can check if RBAC is enabled in your Kubernetes cluster by running kubectl api-versions | grep rbac
- Note: Steps to disable RBAC are outside of the scope of this walkthrough
- Following output indicates RBAC is enabled
```
rbac.authorization.k8s.io/v1
rbac.authorization.k8s.io/v1beta1
```

Nginx Ingress Controller Installation

Minikube

Minikube comes with out of the box support for nginx ingress controller
To enable default nginx ingress controller, run minikube addons enable ingress
Check the status of nginx ingress by running minikube addons list | grep ingress

GKE (Google Kubernetes Engine) on Google Cloud Platform

Update `kubectl` context

Check current context by running kubectl config current-context
If you do not see desired kubernetes cluster in output of above command, you need to set appropriate context.
To set a GKE cluster in context:
- Get cluster/zone name: gcloud container clusters list
- Update context: gcloud container clusters get-credentials <cluster_name> --zone <zone_name>
- Replace <cluster_name> with actual cluster name and <zone_name> with actual zone name
- Example: gcloud container clusters get-credentials cluster-20062018-121027 --zone asia-south1-a
- Expected Output:
```
Fetching cluster endpoint and auth data.
kubeconfig entry generated for cluster-20062018-121027.
```

Install Helm and Tiller

Helm

Run GCloud Shell from Google Cloud platform Console
Install helm

curl -o get_helm.sh https://raw.githubusercontent.com/kubernetes/helm/master/scripts/get
chmod +x get_helm.sh
./get_helm.sh

Expected Output:

Downloading https://kubernetes-helm.storage.googleapis.com/helm-v2.9.1-linux-amd64.tar.gz
Preparing to install into /usr/local/bin
helm installed into /usr/local/bin/helm
Run 'helm init' to configure helm.

Tiller

Create a service account for tiller in kube-system namespace.

kubectl create serviceaccount --namespace kube-system tiller

Create a ClusterRoleBinding for tiller assigning it the role of cluster-admin and linking it with the service account we created for tiller in kube-system namespace

kubectl create clusterrolebinding tiller-cluster-role --clusterrole=cluster-admin --serviceaccount=kube-system:tiller

Create deployment for tiller by the way of initiating helm

helm init --service-account tiller --upgrade

Install Nginx Ingress Controller on GKE

Since we checked previously that RBAC is enabled on kubernetes cluster, lets install nginx-ingress helm chart with RBAC rules

helm install --name nginx-ingress stable/nginx-ingress --set rbac.create=true

Somewhere in output under heading v1/Service you should see:

==> v1/Service
NAME                           TYPE          CLUSTER-IP    EXTERNAL-IP  PORT(S)                     AGE
nginx-ingress-controller       LoadBalancer  10.35.246.69  <pending>    80:30505/TCP,443:31687/TCP  0s
nginx-ingress-default-backend  ClusterIP     10.35.241.12  <none>       80/TCP                      0s

When the <pending> under EXTERNAL-IP column changes to an actual IP address, your GCP load balancer is ready.
- Use watch kubectl get svc to constantly keep checking if the LoadBalancer is up (i.e. IP address is allocated to nginx-ingress-controller service)

Now go ahead and deploy your ingress resources in respective namespaces. Checkout file named cross-ns-resources.yaml in this repository.

Test our Cross Namespace Nginx Ingress on GKE

Deploy all resources in cross-ns-resources.yaml by running

kubectl apply -f cross-ns-resources.yaml

Edit your /etc/hosts and add following lines towards the end:

35.200.162.167 machine.deep
35.200.162.167 human.deep

Replace 35.200.162.167 with the actual IP Address of your Load Balancer as we checked under v1/Service heading at the time of installing nginx-ingress helm chart
Navigate to machine.deep in your browser, output should be in the lines of:
Navigate to human.deep in your browser, output should be in the lines of: