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Services in K8s

  • In Kubernetes, a Service is a method for exposing a network application that is running as one or more Pods in your cluster.

  • The set of Pods targeted by a Service is usually determined by a selector that you define.

  • For example, consider a stateless image-processing backend which is running with 3 replicas. Those replicas are fungible—frontends do not care which backend they use. While the actual Pods that compose the backend set may change, the frontend clients should not need to be aware of that, nor should they need to keep track of the set of backends themselves. The Service abstraction enables this decoupling.
  • Here is an example of a service of type NodePort which exposes a port(Nodeport) of a Node in the kubernetes cluster and also describes which port on the pod would the calls be forwarded to (targetPort) - *A nodePort is a temporary solution to expose the applications to the internet, usually done for testing purposes, other types of services e.g. load-balancer etc. can provide a permanent solution
    • apiVersion: v1
kind: Service
metadata:
  name: eggplantsapi-service
spec:
  selector:
    app: eggplants
  ports:
    - port: 80  # Expose on port 80 for simplicity, adjust as needed
      nodePort: 30100
      targetPort: 3000
      name: http
    - port: 81
      nodePort: 30101
      targetPort: 5000
      name: http-api
  type: NodePort
  • https://www.youtube.com/watch?v=RQbc_Yjb9ls
  • Difference between LoadBalancer service and other types of services is that LoadBalancer get an external public IP address
  • A Loadbalancer's IP address is stable
  • A Loadbalancer routes traffic to the nodes in your cluster.
  • When a LoadBalancer service is created then the underlying ClusterIP and NodePort services are also created.
  • Know more about loadbalancer service: https://www.youtube.com/watch?v=7o6koGCsoSc


  • Different Service Types




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