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Kubernetes Networking: Endpoint & EndpointSlice

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• Kubernetes Networking: Endpoint \& EndpointSlice
  • Endpoints object
    • Imperative Commands
    • Lab: Get Endpoint
  • EndpointSlice object
    • Imperative Command
    • Lab: Get EndpointSlices
  • Managing service endpoints manually
    • Lab: Create service withtout label selector

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Endpoints object

• endpoints

  • the object to which a service forwards traffic can be anything that has an IP address.

• fully managed by Kubernetes.

  • created by Kubernetes when creating the associated Service objects.
  • Each time a new pod appears or disappears that matches the Service’s label selector, Kubernetes updates the Endpoints object` to add or remove the endpoint associated with the pod.

• Endpoint in service

  • Services do not send traffic to Pods directly.
  • Services send traffic to the Endpoints object that contains the real Pod IPs.

• Each Endpoints object contains a list of IP and port combinations

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Imperative Commands

CMD	DESC
kubectl get endpoints /kubectl get ep	List all Endpoints objects in the current namespace
kubectl get endpoints --all-namespaces	List endpoints across all namespaces
kubectl get endpoints -l app=nginx	Filter endpoints by label
kubectl get endpoints -o wide	Show endpoints with IP:Port details
kubectl describe endpoints <name>	View detailed endpoint info (ready/not-ready addresses, ports)
kubectl get endpoints <svc>	Show which pod IPs are backing a Service
kubectl get endpoints <svc> -o yaml	Export endpoints manifest
kubectl edit endpoints <name>	Live-edit endpoints object
kubectl delete endpoints <name>	Delete an Endpoints object

• incorrect command: kubectl get endpoint
  • endpoints must be with s

---

Lab: Get Endpoint

kubectl get svc
# NAME                TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)          AGE
# demo-nodeport-svc   NodePort    10.102.182.197   <none>        8080:30977/TCP   3h10m

kubectl get endpoints
# Warning: v1 Endpoints is deprecated in v1.33+; use discovery.k8s.io/v1 EndpointSlice
# NAME                ENDPOINTS                   AGE
# demo-nodeport-svc   10.1.3.20:80,10.1.3.21:80   3h7m

kubectl describe endpoints demo-nodeport-svc
# Warning: v1 Endpoints is deprecated in v1.33+; use discovery.k8s.io/v1 EndpointSlice
# Name:         demo-nodeport-svc
# Namespace:    default
# Labels:       endpoints.kubernetes.io/managed-by=endpoint-controller
# Annotations:  endpoints.kubernetes.io/last-change-trigger-time: 2025-12-28T20:44:02Z
# Subsets:
#   Addresses:          10.1.3.20,10.1.3.21
#   NotReadyAddresses:  <none>
#   Ports:
#     Name  Port  Protocol
#     ----  ----  --------
#     http  80    TCP

# Events:  <none>

kubectl get endpoints demo-nodeport-svc -o yaml
# Warning: v1 Endpoints is deprecated in v1.33+; use discovery.k8s.io/v1 EndpointSlice
# apiVersion: v1
# kind: Endpoints
# metadata:
#   annotations:
#     endpoints.kubernetes.io/last-change-trigger-time: "2025-12-28T20:44:02Z"
#   creationTimestamp: "2025-12-28T20:44:02Z"
#   labels:
#     endpoints.kubernetes.io/managed-by: endpoint-controller
#   name: demo-nodeport-svc
#   namespace: default
#   resourceVersion: "2664611"
#   uid: ffd1ea32-ea57-453a-b9c5-8a0a3b68155c
# subsets:
# - addresses:
#   - ip: 10.1.3.20
#     nodeName: docker-desktop
#     targetRef:
#       kind: Pod
#       name: nginx-c8585b9f-jxt4k
#       namespace: default
#       uid: 16e36478-091d-4a1d-b609-91c9c8e037c0
#   - ip: 10.1.3.21
#     nodeName: docker-desktop
#     targetRef:
#       kind: Pod
#       name: nginx-c8585b9f-zrrbv
#       namespace: default
#       uid: e631f551-40c7-420a-add7-8535b5598e02
#   ports:
#   - name: http
#     port: 80
#     protocol: TCP

---

EndpointSlice object

• EndpointSlice object

  • splits the endpoints of a single service into multiple slices.

• EndpointSlices are created and managed automatically.

• Endpoints object contains multiple endpoint subsets
  • each EndpointSlice contains only one.
• If two groups of pods expose the service on different ports,
  • they appear in two different EndpointSlice objects.
• an EndpointSlice object supports a maximum of 1000 endpoints
  • by default Kubernetes only adds up to 100 endpoints to each slice.
• The number of ports in a slice is also limited to 100.

---

Imperative Command

CMD	DESC
kubectl get endpointslices /kubectl get endpointslice	List all EndpointSlice objects
kubectl get endpointslices --all-namespaces	List slices across all namespaces
kubectl get endpointslices -l kubernetes.io/service-name=myapp	Get EndpointSlices of a Service
kubectl describe endpointslice <name>	Show detailed endpoint readiness & topology
kubectl get endpointslice <name> -o yaml	Export EndpointSlice manifest
kubectl delete endpointslice <name>	Delete an EndpointSlice
kubectl create endpointslice <name> --dry-run=client -o yaml	Generate slice manifest
kubectl edit endpointslice <name>	Live-edit an EndpointSlice

---

Lab: Get EndpointSlices

kubectl get endpointslices
# NAME                      ADDRESSTYPE   PORTS   ENDPOINTS             AGE
# demo-nodeport-svc-l6zl8   IPv4          80      10.1.3.20,10.1.3.21   5h54m

# list slices for a service
kubectl get endpointslices -l kubernetes.io/service-name=demo-nodeport-svc
# NAME                      ADDRESSTYPE   PORTS   ENDPOINTS             AGE
# demo-nodeport-svc-l6zl8   IPv4          80      10.1.3.20,10.1.3.21   6h2m

# show details for a svc
kubectl describe endpointslice demo-nodeport-svc
# Name:         demo-nodeport-svc-l6zl8
# Namespace:    default
# Labels:       endpointslice.kubernetes.io/managed-by=endpointslice-controller.k8s.io
#               kubernetes.io/service-name=demo-nodeport-svc
# Annotations:  endpoints.kubernetes.io/last-change-trigger-time: 2025-12-28T20:44:02Z
# AddressType:  IPv4
# Ports:
#   Name  Port  Protocol
#   ----  ----  --------
#   http  80    TCP
# Endpoints:
#   - Addresses:  10.1.3.20
#     Conditions:
#       Ready:    true
#     Hostname:   <unset>
#     TargetRef:  Pod/nginx-c8585b9f-jxt4k
#     NodeName:   docker-desktop
#     Zone:       <unset>
#   - Addresses:  10.1.3.21
#     Conditions:
#       Ready:    true
#     Hostname:   <unset>
#     TargetRef:  Pod/nginx-c8585b9f-zrrbv
#     NodeName:   docker-desktop
#     Zone:       <unset>
# Events:         <none>

---

Managing service endpoints manually

• When you create a Service object with a label selector, Kubernetes automatically creates and manages the Endpoints and EndpointSlice objects and uses the selector to determine the service endpoints.

• can also manage endpoints manually by creating the Service object without a label selector.

  • must create the Endpoints object yourself.
  • don’t need to create the EndpointSlice objects because Kubernetes mirrors the Endpoints object to create corresponding EndpointSlices.
• use case:
  • make an existing external service accessible to pods in cluster under a different name. This way, the service can be found through the cluster DNS and environment variables.

---

Lab: Create service withtout label selector

apiVersion: v1
kind: Service
metadata:
  name: external-service
spec:
  ports:
    - name: http
      port: 80

• Creating an Endpoints object

apiVersion: v1
kind: Endpoints
metadata:
  name: external-service # match service name
subsets:
  - addresses:
      - ip: 1.1.1.1 # the ip outside the cluster
      - ip: 2.2.2.2 # the ip outside the cluster
    ports:
      - name: http
        port: 88