What is Kubernetes EndpointSlice?

Question

Accepted Answer

**EndpointSlice** — scalable replacement for Endpoints for large Services.

**Endpoints problem:** single object = all Pod IPs. With 10k+ Pods the object becomes huge.

**EndpointSlice:** splits into multiple objects (100 endpoints each).

**Example:**
```yaml
apiVersion: discovery.k8s.io/v1
kind: EndpointSlice
metadata:
  name: myapp-abc123
  namespace: production
  labels:
    kubernetes.io/service-name: myapp
addressType: IPv4
ports:
  - name: http
    port: 8080
    protocol: TCP
endpoints:
  - addresses:
      - "10.0.0.5"
    conditions:
      ready: true
      serving: true
      terminating: false
    nodeName: node-1
    zone: us-east-1a
  - addresses:
      - "10.0.1.8"
    conditions:
      ready: true
      serving: true
      terminating: false
    nodeName: node-2
    zone: us-east-1b
```

**Topology-aware routing (K8s 1.27+):**
```yaml
apiVersion: v1
kind: Service
metadata:
  name: myapp
  annotations:
    service.kubernetes.io/topology-mode: Auto
spec:
  internalTrafficPolicy: Local
  ...
```

**internalTrafficPolicy: Local** — traffic goes only to own zone (reduces latency and cost).

**Verification:** `kubectl get endpointslices -l kubernetes.io/service-name=myapp`.

DevOps: What is Kubernetes EndpointSlice?