Endpoints and Endpoint Slices Overview

Kubernetes Services provide a stable network endpoint for Pods, but under the hood, Services rely on two resources—Endpoints and Endpoint Slices—to map Service selectors to Pod IPs and ports. This guide explains how each resource works, their roles in traffic routing, and how to inspect them.

Endpoints

An Endpoint object in Kubernetes keeps track of all Pod IPs and ports that back a Service. When you create a Service, Kubernetes uses its label selector to identify matching Pods and generates an Endpoints object with the same name.

The image illustrates a network diagram showing a service (SVC) connected to endpoints with specific IP addresses, which in turn connect to three different pods.

As Pods are created, deleted, or updated, the Endpoints object is managed automatically by the control plane—no manual edits are needed.

Inspecting an Endpoints Object

Use kubectl to view the Endpoints backing a Service:

kubectl get endpoints SERVICE_NAME -o yaml

Example output:

subsets:
- addresses:
  - ip: 10.244.1.172
    nodeName: node
    targetRef:
      kind: Pod
      name: pod-name-5f68f556c8-25nb9
      namespace: default
  ports:
  - name: HTTP
    port: 80
    protocol: TCP

Fields explained:

subsets: Groups of addresses and ports.
addresses: Lists Pod IPs and node names.
ports: Indicates which port names and protocols are exposed.

Limitations of Endpoints

Warning

Each Endpoints object can hold up to 1,000 addresses. In large clusters or high-scale environments, this cap may lead to performance bottlenecks or truncated endpoint lists.

Resource	Maximum Addresses	Impact
Endpoints	1,000	May require Service sharding or slicing

The image is a slide titled "Endpoint – Limitations," indicating that Kubernetes restricts endpoints to 1,000.

Endpoint Slices

Introduced as a beta feature in v1.17 and GA in v1.21, Endpoint Slices solve the scalability issues of Endpoints by splitting Pod endpoints into multiple, smaller objects. Each slice holds a subset of IPs, ports, and metadata, reducing control-plane load.

The image is a diagram titled "Endpoint Slices," illustrating an advanced, scalable way to manage a network, with a network icon and a gradient label.

Note

Endpoint Slices support optional fields like topology hints, enabling you to optimize traffic routing based on node labels or zones.

How Endpoint Slices Work

The image illustrates how Endpoint Slices work in Kubernetes, showing the relationship between services, endpoint slices, and pods, with notes on management and dynamic updates.

Slices per Service: Multiple Endpoint Slice objects can coexist for one Service.
Subset Size: By default, each slice holds up to 100 endpoints, configurable via the EndpointSlice API.
Automatic Updates: The control plane synchronizes slices as Pods change state.

Viewing Endpoint Slices

kubectl get endpointslices SERVICE_NAME-UID -o yaml

Sample YAML:

endpoints:
- addresses:
  - 10.244.1.172
  conditions:
    ready: true
    serving: true
    terminating: false
  nodeName: worker
  targetRef:
    kind: Pod
    name: pod-name-5f68f556c8-25nb9
    namespace: default
    uid: e77f4587-6d20-48bb-b5f6-f6df51a886d
  ports:
  - name: http
    port: 80
    protocol: TCP

Feature	Endpoints	Endpoint Slices
Scalability	≤1,000 IPs	Configurable slice size, multiple slices per Service
Metadata & Topology	Limited	Supports zone hints, custom labels
Control-Plane Load	Higher	Distributed across slices, fewer large updates overall

References

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