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Services

A Service exposes a set of Pods as a network service with a stable IP address and DNS name.

  • Pods are selected via label selectors
  • Provides load balancing across the selected Pods
  • The Service IP remains stable even as Pods are created and destroyed
  • DNS record: <service-name>.<namespace>.svc.cluster.local
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Service Types​

ClusterIP (default)​

  • Exposes the Service on an internal IP within the cluster
  • Only reachable from within the cluster
apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  type: ClusterIP
  selector:
    app: my-app
  ports:
  - port: 80
    targetPort: 8080

NodePort​

  • Exposes the Service on each node's IP at a static port (range: 30000-32767)
  • Accessible from outside the cluster via <NodeIP>:<NodePort>
  • A ClusterIP is also created automatically
spec:
  type: NodePort
  ports:
  - port: 80
    targetPort: 8080
    nodePort: 30080

LoadBalancer​

  • Provisions an external load balancer (cloud provider dependent)
  • Exposes the Service externally using the cloud provider's load balancer
  • NodePort and ClusterIP are also created automatically
spec:
  type: LoadBalancer
  ports:
  - port: 80
    targetPort: 8080

ExternalName​

  • Maps the Service to an external DNS name (CNAME record)
  • No proxying; returns the CNAME record directly
  • Useful for integrating external services into the cluster's DNS
spec:
  type: ExternalName
  externalName: my-database.example.com
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Headless Services​

  • Created by setting clusterIP: None
  • No load balancing or single Service IP
  • DNS returns the IP addresses of all the Pods directly
  • Commonly used with StatefulSets for stable network identities
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