Expose Nginx to public in Kubernetes

After getting kubernetes up and running and the dashboard online we proceed to getting our first service public to the world.

When you do not use a load balancer provided by your cloud provider, kubernetes offers you two options for exposing ports: NodePort or using an ingress. Ingress is clearly the way to go, enabling you to have multiple services using the same port (this article explains the difference in more detail).

Exposing Nginx using Ingress

Make sure you have ingress enabled. If you installed microk8s you can do the following:

microk8s.enable ingress

Next we can create our configuration:

---
# https://kubernetes.io/docs/concepts/services-networking/ingress/
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: http-ingress
spec:
  backend:
    serviceName: mainservice
    servicePort: 80
---
# https://kubernetes.io/docs/concepts/workloads/controllers/deployment/#creating-a-deployment
apiVersion: apps/v1
kind: Deployment
metadata:
  name: cdn
spec:
  selector:
    matchLabels:
      appservgroup: mainserv
  replicas: 1
  template: # create pods; pod template
    metadata:
      labels:
        appservgroup: mainserv
    spec:
      containers:
      - name: cdn
        image: nginx:alpine
        ports:
        - containerPort: 80
---
# https://kubernetes.io/docs/concepts/services-networking/connect-applications-service/#exposing-pods-to-the-cluster
apiVersion: v1
kind: Service
metadata:
  name: mainservice
  namespace: default
#  labels:
#    exposelabelexample: http
spec:
#  type: NodePort
  ports:
  - name: http
    port: 80
#    protocol: TCP # default = TCP
#    targetPort: 80 # you can skip this if it's the same as port
  selector:
    appservgroup: mainserv

which we save as boilerplate.yml

This boilerplate contains three yaml files, which we combined and separated with ---.

If we now start this:

kubectl create -f boilerplate.yml

we can view it in our dashboard (select all namespaces visible). And it should be publicly accessible when it has been started.

To stop and remove use the same configuration file:

kubectl delete -f boilerplate.yml

Please see the kubernetes documentation about ingress for more detailed examples using hosts and paths.