K8s新手系列之Endponit

晚风吹人冷 發表於 2025-5-10 21:15:00

<h2 id="概述">概述</h2>
<p>官方文档：https://kubernetes.io/zh-cn/docs/reference/kubernetes-api/service-resources/endpoints-v1/</p>
<p><code>Endpoint</code>简称<code>ep</code></p>
<p>Endpoint是kubernetes中的一个资源对象，存储在etcd中，用来记录一个service对应的所有pod的访问地址，它是根据service配置文件中selector描述产生的。</p>
<p>一个Service由一组Pod组成，这些Pod通过Endpoints暴露出来，Endpoints是实现实际服务的端点集合。换句话说，service和pod之间的联系是通过endpoints实现的。</p>
<p><img src="https://img2024.cnblogs.com/blog/3468887/202505/3468887-20250510154721378-1501340591.png" alt="image" loading="lazy"></p>
<h2 id="负载分发策略">负载分发策略</h2>
<p>对Service的访问被分发到了后端的Pod上去，目前kubernetes提供了两种负载分发策略：</p>
<ul>
<li>如果不定义，默认使用kube-proxy的策略，比如随机、轮询</li>
<li>基于客户端地址的会话保持模式，即来自同一个客户端发起的所有请求都会转发到固定的一个Pod上，此模式可以使在spec中添加sessionAffinity:ClientIP选项</li>
</ul>
<h2 id="验证endpoint">验证Endpoint</h2>
<h3 id="创建service和deploy">创建service和deploy</h3>
<pre><code># cat nginx-deploy.yaml
# service
apiVersion: v1
kind: Service
metadata:
namespace: default
name: nginx-svc-clusterip
spec:
type: ClusterIP
selector:
app: nginx
ports:
- name: clusterip-nginx
port: 80
targetPort: 80
protocol: TCP

---
# deploy
apiVersion: apps/v1
kind: Deployment
metadata:
name: deployment-nginx
namespace: default
spec:
replicas: 3
selector:
matchLabels:
   app: nginx
template:
metadata:
   name: pod-nginx
   labels:
   app: nginx
spec:
   containers:
   - name: container-nginx
   image: nginx:1.14.1
   restartPolicy: Always
</code></pre>
<h3 id="查看创建成功对应的资源">查看创建成功对应的资源</h3>
<pre><code># 查看pod
# kubectl get po -o wide
NAME                            READY STATUS          RESTARTS       AGE IP             NODE NOMINATED NODE READINESS GATES
deployment-nginx-6d84458cd8-g8lkv 1/1 Running          0             35m 100.117.144.139 node01 <none>       <none>
deployment-nginx-6d84458cd8-j8m6c 1/1 Running          0             35m 100.95.185.234 node02 <none>       <none>
deployment-nginx-6d84458cd8-znr7t 1/1 Running          0             35m 100.117.144.140 node01 <none>       <none>

# 查看svc详情，注意Endpoints列表是和pod的IP保持一致的
# kubectl describe svc nginx-svc-clusterip
Name:          nginx-svc-clusterip
Namespace:       default
Labels:          <none>
Annotations:    <none>
Selector:       app=nginx
Type:          ClusterIP
IP Family Policy:SingleStack
IP Families:    IPv4
IP:             10.96.1.52
IPs:             10.96.1.52
Port:          clusterip-nginx80/TCP
TargetPort:    80/TCP
Endpoints:       100.117.144.139:80,100.117.144.140:80,100.95.185.234:80
Session Affinity:None
Events:          <none>

# 查看endpoints资源
# kubectl get endpoints
NAME                ENDPOINTS                                              AGE
nginx-svc-clusterip 100.117.144.139:80,100.117.144.140:80,100.95.185.234:80 36m
</code></pre>
<h3 id="当我们重启pod之后看看endpoints列表会发生什么">当我们重启Pod之后看看Endpoints列表会发生什么</h3>
<p>重启Pod</p>
<pre><code># kubectl delete po deployment-nginx-6d84458cd8-g8lkv deployment-nginx-6d84458cd8-j8m6c deployment-nginx-6d84458cd8-znr7t
pod "deployment-nginx-6d84458cd8-g8lkv" deleted
pod "deployment-nginx-6d84458cd8-j8m6c" deleted
pod "deployment-nginx-6d84458cd8-znr7t" deleted
</code></pre>
<p>查看资源，发现对应的IP是会进行变化的</p>
<pre><code># 查看Pod
# kubectl get po -o wide
NAME                            READY STATUS          RESTARTS       AGE IP             NODE NOMINATED NODE READINESS GATES
deployment-nginx-6d84458cd8-4z4cb 1/1 Running          0             7s 100.95.185.236 node02 <none>       <none>
deployment-nginx-6d84458cd8-ht2z9 1/1 Running          0             7s 100.117.144.141 node01 <none>       <none>
deployment-nginx-6d84458cd8-ns47j 1/1 Running          0             7s 100.95.185.238 node02 <none>       <none>
# 查看service
# kubectl describe svc nginx-svc-clusterip
Name:          nginx-svc-clusterip
Namespace:       default
Labels:          <none>
Annotations:    <none>
Selector:       app=nginx
Type:          ClusterIP
IP Family Policy:SingleStack
IP Families:    IPv4
IP:             10.96.1.52
IPs:             10.96.1.52
Port:          clusterip-nginx80/TCP
TargetPort:    80/TCP
Endpoints:       100.117.144.141:80,100.95.185.236:80,100.95.185.238:80
Session Affinity:None
Events:          <none>
#查看endpoints
# kubectl get endpoints
NAME                ENDPOINTS                                              AGE
kubernetes          10.0.0.30:6443                                        78m
nginx-svc-clusterip 100.117.144.141:80,100.95.185.236:80,100.95.185.238:80 39m

</code></pre>
<h2 id="编写一个属于自己endpoints">编写一个属于自己Endpoints</h2>
<p>Endpoints资源是通过name和namespace两个字段与Service进行关联的，所以Endpoints的名称和Service的名称相同.</p>
<p>示例：</p>
<pre><code># cat ep.yaml
# Endpoints资源
apiVersion: v1
kind: Endpoints
metadata:
name: harbor-huangxin
subsets:
- addresses:
   - ip: 10.0.0.250
   ports:
   - port: 80
   protocol: TCP
---
# Service资源
apiVersion: v1
kind: Service
metadata:
name: harbor-huangxin
spec:
type: ClusterIP
ports:
   - port: 80
      targetPort: 80
</code></pre>
<h3 id="查看一下资源">查看一下资源</h3>
<pre><code># 查看service
# kubectl describe svc endpoint-huangsir
Name:          endpoint-huangsir
Namespace:       default
Labels:          <none>
Annotations:    <none>
Selector:       <none>
Type:          ClusterIP
IP Family Policy:SingleStack
IP Families:    IPv4
IP:             10.96.1.127
IPs:             10.96.1.127
Port:          <unset>80/TCP
TargetPort:    80/TCP
Endpoints:       10.0.0.250:80
Session Affinity:None
Events:          <none>
# 查看endpoint
# kubectl get ep endpoint-huangsir
NAME          ENDPOINTS    AGE
endpoint-huangsir 10.0.0.250:80 51s
</code></pre>

</div>
<div id="MySignature" role="contentinfo">
<p>本文来自博客园，作者：huangSir-devops，转载请注明原文链接：https://www.cnblogs.com/huangSir-devops/p/18869685，微信Vac6666666，欢迎交流</p><br><br>
来源：https://www.cnblogs.com/huangSir-devops/p/18869685

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K8s新手系列之Endponit