🔗 Kubernetes Services (SVC)

A Service in Kubernetes provides a stable network endpoint to access a set of Pods. It abstracts access through selectors and DNS names, enabling loose coupling between client applications and Pods.

🌐 Service Basics

📌 Service Flow

Service ➡️ Endpoint ➡️ Pods

Services group Pods behind a single access point.
They get a cluster-wide DNS name automatically.
Use label selectors to forward traffic to matching Pods.

🧭 Types of Services

ClusterIP (default)
- Only reachable within the cluster.
NodePort
- Exposes the service via a static port on each node.
LoadBalancer
- Creates an external IP address using a cloud provider.

🧪 Useful Commands

🔍 Get Endpoints

kubectl get ep -n <namespace>

📄 Get Services

kubectl get svc -n <namespace>

🔁 Port Forwarding

To access a service from your local machine, forward a local port to the service port:

kubectl port-forward -n <namespace> svc/<service-name> <local-port>:<target-port>

Example: Forward local port 8080 to port 80 of my-service in the mynamespace namespace:
kubectl port-forward -n mynamespace svc/my-service 8080:80

You can also bind to all network interfaces:

kubectl port-forward -n <namespace> svc/nginx 80:80 --address 0.0.0.0

🌐 DNS format: <service-name>.<namespace>.svc.cluster.local

🧾 Example Service Manifest

apiVersion: v1
kind: Service
metadata:
  name: nginx
  namespace: ns
  labels:
    app: web-server
spec:
  type: ClusterIP  # Options: ClusterIP, NodePort, LoadBalancer
  selector:
    app: nginx
  ports:
    - name: http
      port: 80
      targetPort: 8080

🔍 Note: The selector must match the labels of the target Pods. 🧠 Tip: Use kubectl describe svc <service-name> to inspect the service and verify connectivity.

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