Exposing and discovering microservices

We deployed our microservice with a deployment. Now, we need to expose it, so that it can be used by other services in the cluster and possibly also make it visible outside the cluster. Kubernetes provides the Service resource for that purpose. Kubernetes services are backed up by pods, identified by labels:

apiVersion: v1
kind: Service
metadata:
  name: nginx
  labels:
    app: nginx
spec:
  ports:
  - port: 80
    protocol: TCP
  selector:
    app: nginx

Services discover each other inside the cluster, using DNS or environment variables. This is the default behavior. But, if you want to make a service accessible to the world, you will normally set an ingress object or a load balancer. We will explore this topic in detail later.