Kubernetes Service types khác nhau thế nào?

ClusterIP expose service nội bộ trong cluster. NodePort mở port trên nodes. LoadBalancer yêu cầu cloud/load balancer provider tạo load balancer bên ngoài. ExternalName map service sang DNS name ngoài cluster.

Ví dụ ClusterIP:

apiVersion: v1
kind: Service
metadata:
  name: api
spec:
  selector:
    app: api
  ports:
    - port: 80
      targetPort: 8000

Phần quan trọng là selector phải match labels của Pods, nếu không Service sẽ không có endpoints.

ClusterIP exposes a service inside the cluster. NodePort opens a port on nodes. LoadBalancer asks the cloud/load balancer provider to create an external load balancer. ExternalName maps a service to an external DNS name.

ClusterIP example:

apiVersion: v1
kind: Service
metadata:
  name: api
spec:
  selector:
    app: api
  ports:
    - port: 80
      targetPort: 8000

The key point is that the selector must match Pod labels, otherwise the Service has no endpoints.