Exposing an application

Let's say you have an application running on your cluster, and you want to expose it on the internet with a public domain name.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
      - name: my-app
        image: my-app:1.0
        ports:
        - containerPort: 8080

Create a LoadBalancer service to expose the app:

apiVersion: v1
kind: Service
metadata:
  name: my-app
spec:
  type: LoadBalancer
  ports:
  - port: 80
    targetPort: 8080
  selector:
    app: my-app

Note

We used here a LoadBalancer service just for simplicity. There are many other ways to get traffic inside your cluster. For more info about services,check the official documentation.

When the load balancer is ready, use kubectl to retrive the external IP.

$ kubectl get service my-app

NAME     TYPE           CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
my-app   LoadBalancer   172.16.18.129   1.1.1.1       80:30773/TCP   1m

Use the external IP to setup a DNSRecord pointing to the load balancer.

apiVersion: dns.k8s.marcocameriero.net/v1alpha1
kind: DNSRecord
metadata:
  name: my-app
spec:
  providerRef:
    name: my-provider
  name: my-app.example.com
  rrset:
    a:
      - 1.1.1.1

The app will now be reachable on:

http://my-app.example.com