Kubernetes Services Explained – Exposing and Connecting Applications

In the previous post, we explored how Kubernetes runs applications using Pods, ReplicaSets, and Deployments.

Now, let’s understand how users — or other applications — can actually access those workloads. That’s where Kubernetes Services come into play.

Why Services Matter

In Kubernetes, Pods are:

• Ephemeral (they can restart, move, or scale)
• Assigned dynamic IPs

So if an app wants to talk to another app (say, frontend to backend), it can’t rely on Pod IPs. That’s where Services step in:

• Provide a stable endpoint (IP and DNS)
• Load balance traffic across a group of Pods
• Simplify service discovery inside the cluster

Types of Kubernetes Services

ClusterIP (default)

• Internal communication only
• Used when apps talk to each other inside the cluster

Example: frontend Pod calling the backend service by name

NodePort

• Exposes a service on each node’s IP at a fixed port (e.g., 30000–32767)
• Enables access from outside the cluster

Good for dev/test environments or basic external exposure

LoadBalancer

• Provisions a cloud-provider external IP + load balancer
• Common in production setups on AWS, GCP, Azure

Ideal for exposing services to the internet

ExternalName

• Maps the service to an external DNS name

Useful when a Kubernetes workload needs to talk to an external system (e.g., database or API outside the cluster)

How Services Work Internally

• Services select Pods using labels (selector)
• Kubernetes creates a virtual IP (ClusterIP) that routes to those Pods
• Traffic is balanced across the available Pods

Example:

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

✅ This exposes Pods with label app: my-app on port 80 inside the cluster.

Real-World Scenarios

Bonus: Ingress vs Service

A Service handles routing based on IP:Port, whereas an Ingress enables HTTP-based routing (e.g., /login, /cart) to multiple services behind a single IP.

We’ll explore Ingress in a future post!

Conclusion

Kubernetes Services decouple your workload’s location from how it’s accessed. They offer consistency, scalability, and discoverability — essential in microservice environments.