Kubernetes核心原理（一）之API Server

素颜马尾好姑娘i 2022-06-11 05:12 187阅读 0赞

[原文链接][Link 1]

1. API Server简介 k8s API Server提供了k8s各类资源对象（pod,RC,Service等）的增删改查及watch等HTTP Rest接口，是整个系统的数据总线和数据中心。

本文CSDN博客地址：[http://blog.csdn.net/huwh\_/article/details/75675706][http_blog.csdn.net_huwh_article_details_75675706]

# 1. API Server简介 #

k8s API Server提供了k8s各类资源对象（pod,RC,Service等）的增删改查及watch等HTTP Rest接口，是整个系统的数据总线和数据中心。

kubernetes API Server的功能：

1.  提供了集群管理的REST API接口(包括认证授权、数据校验以及集群状态变更)；
2.  提供其他模块之间的数据交互和通信的枢纽（其他模块通过API Server查询或修改数据，只有API Server才直接操作etcd）;
3.  是资源配额控制的入口；
4.  拥有完备的集群安全机制.

kube-apiserver工作原理图

![Center][]

2. 如何访问kubernetes API

k8s通过kube-apiserver这个进程提供服务，该进程运行在单个k8s-master节点上。默认有两个端口。

## 2.1. 本地端口 ##

1.  该端口用于接收HTTP请求；
2.  该端口默认值为8080，可以通过API Server的启动参数“--insecure-port”的值来修改默认值；
3.  默认的IP地址为“localhost”，可以通过启动参数“--insecure-bind-address”的值来修改该IP地址；
4.  非认证或授权的HTTP请求通过该端口访问API Server。

## 2.2. 安全端口 ##

1.  该端口默认值为6443，可通过启动参数“--secure-port”的值来修改默认值；
2.  默认IP地址为非本地（Non-Localhost）网络端口，通过启动参数“--bind-address”设置该值；
3.  该端口用于接收HTTPS请求；
4.  用于基于Tocken文件或客户端证书及HTTP Base的认证；
5.  用于基于策略的授权；
6.  默认不启动HTTPS安全访问控制。

## 2.3. 访问方式 ##

Kubernetes REST API可参考[https://kubernetes.io/docs/api-reference/v1.6/][https_kubernetes.io_docs_api-reference_v1.6]

### 2.3.1. curl ###

### 2.3.2. Kubectl Proxy ###

Kubectl Proxy代理程序既能作为API Server的反向代理，也能作为普通客户端访问API Server的代理。通过master节点的8080端口来启动该代理程序。

kubectl proxy --port=8080 &

具体见kubectl proxy --help

### 2.3.3. kubectl客户端 ###

命令行工具kubectl客户端，通过命令行参数转换为对API Server的REST API调用，并将调用结果输出。

命令格式：kubectl \[command\] \[options\]

具体可参考[Kubernetes常用命令][Kubernetes]

### 2.3.4. 编程方式调用 ###

使用场景：

1、运行在Pod里的用户进程调用kubernetes API,通常用来实现分布式集群搭建的目标。

2、开发基于kubernetes的管理平台，比如调用kubernetes API来完成Pod、Service、RC等资源对象的图形化创建和管理界面。可以使用kubernetes提供的Client Library。

具体可参考[https://github.com/kubernetes/client-go][https_github.com_kubernetes_client-go]。

# 3. 通过API Server访问Node、Pod和Service #

k8s API Server最主要的REST接口是资源对象的增删改查，另外还有一类特殊的REST接口—k8s Proxy API接口，这类接口的作用是代理REST请求，即kubernetes API Server把收到的REST请求转发到某个Node上的kubelet守护进程的REST端口上，由该kubelet进程负责响应。

## 3.1. Node相关接口 ##

关于Node相关的接口的REST路径为：/api/v1/proxy/nodes/\{name\}，其中\{name\}为节点的名称或IP地址。

这里获取的Pod信息来自Node而非etcd[数据库][Link 2]，两者时间点可能存在偏差。如果在kubelet进程启动时加--enable-debugging-handles=true参数，那么kubernetes Proxy API还会增加以下接口：

<table style="border-collapse:collapse; border-spacing:0px; background:none; max-width:100%; margin:0px; padding:0px; border:0px; float:none; vertical-align:baseline; height:auto; width:1172.22px; display:block; overflow:visible; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; font-size:10pt!important; min-height:auto!important"> 
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     <div style="margin:0px; padding:0px 1em 0px 0px; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; white-space:nowrap; outline:0px!important; background:0px 0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; font-size:10pt!important; min-height:auto!important"> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/api/v1/proxy/nodes/</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">{name}</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/run</code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(0,130,0); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">#在节点上运行某个容器</code> 
     </div> 
     <div style="margin:0px; padding:0px 1em 0px 0px; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; white-space:nowrap; outline:0px!important; background:0px 0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; font-size:10pt!important; min-height:auto!important"> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/api/v1/proxy/nodes/</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">{name}</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/exec</code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(0,130,0); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">#在节点上的某个容器中运行某条命令</code> 
     </div> 
     <div style="margin:0px; padding:0px 1em 0px 0px; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; white-space:nowrap; outline:0px!important; background:0px 0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; font-size:10pt!important; min-height:auto!important"> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/api/v1/proxy/nodes/</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">{name}</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/attach</code>&nbsp;&nbsp;&nbsp; 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(0,130,0); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">#在节点上attach某个容器</code> 
     </div> 
     <div style="margin:0px; padding:0px 1em 0px 0px; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; white-space:nowrap; outline:0px!important; background:0px 0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; font-size:10pt!important; min-height:auto!important"> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/api/v1/proxy/nodes/</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">{name}</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/portForward</code>&nbsp;&nbsp;&nbsp; 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(0,130,0); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">#实现节点上的Pod端口转发</code> 
     </div> 
     <div style="margin:0px; padding:0px 1em 0px 0px; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; white-space:nowrap; outline:0px!important; background:0px 0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; font-size:10pt!important; min-height:auto!important"> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/api/v1/proxy/nodes/</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">{name}</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/logs</code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(0,130,0); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">#列出节点的各类日志信息</code> 
     </div> 
     <div style="margin:0px; padding:0px 1em 0px 0px; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; white-space:nowrap; outline:0px!important; background:0px 0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; font-size:10pt!important; min-height:auto!important"> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/api/v1/proxy/nodes/</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">{name}</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/metrics</code>&nbsp;&nbsp; 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(0,130,0); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">#列出和该节点相关的Metrics信息</code> 
     </div> 
     <div style="margin:0px; padding:0px 1em 0px 0px; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; white-space:nowrap; outline:0px!important; background:0px 0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; font-size:10pt!important; min-height:auto!important"> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/api/v1/proxy/nodes/</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">{name}</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/runningpods</code>&nbsp;&nbsp; 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(0,130,0); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">#列出节点内运行中的Pod信息</code> 
     </div> 
     <div style="margin:0px; padding:0px 1em 0px 0px; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; white-space:nowrap; outline:0px!important; background:0px 0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; font-size:10pt!important; min-height:auto!important"> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/api/v1/proxy/nodes/</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">{name}</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/debug/pprof</code>&nbsp;&nbsp; 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(0,130,0); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">#列出节点内当前web服务的状态，包括CPU和内存的使用情况</code> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

## 3.2. Pod相关接口 ##

<table style="border-collapse:collapse; border-spacing:0px; background:none; max-width:100%; margin:0px; padding:0px; border:0px; float:none; vertical-align:baseline; height:auto; width:1172.22px; display:block; overflow:visible; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; font-size:10pt!important; min-height:auto!important"> 
 <tbody style="margin:0px; padding:0px; border:0px; background:none; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; font-size:10pt!important; min-height:auto!important"> 
  <tr style="margin:0px; padding:0px; border:0px; background:none; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; font-size:10pt!important; min-height:auto!important"> 
   <td style="margin:0px; padding:0px 0px 0px 15px; border:0px; background:none; float:none; vertical-align:baseline; height:auto; width:1157.22px; overflow:visible; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace!important; font-size:10pt!important; min-height:auto!important"> 
    <div title="Hint: double-click to select code" style="margin:15px 0px 0px; padding:0px 0px 15px; width:auto; border:0px; background:none; float:none; vertical-align:baseline; height:auto; overflow:visible; white-space:pre-wrap; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; font-size:10pt!important; min-height:auto!important"> 
     <div style="margin:0px; padding:0px 1em 0px 0px; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; white-space:nowrap; outline:0px!important; background:0px 0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; font-size:10pt!important; min-height:auto!important"> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/api/v1/proxy/namespaces/</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">{namespace}</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/pods/</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">{name}/{path:*}&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(0,130,0); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">#访问pod的某个服务接口</code> 
     </div> 
     <div style="margin:0px; padding:0px 1em 0px 0px; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; white-space:nowrap; outline:0px!important; background:0px 0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; font-size:10pt!important; min-height:auto!important"> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/api/v1/proxy/namespaces/</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">{namespace}</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/pods/</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">{name}&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(0,130,0); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">#访问Pod</code> 
     </div> 
     <div style="margin:0px; padding:0px 1em 0px 0px; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; white-space:nowrap; outline:0px!important; background:0px 0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; font-size:10pt!important; min-height:auto!important"> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(0,130,0); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">#以下写法不同，功能一样</code> 
     </div> 
     <div style="margin:0px; padding:0px 1em 0px 0px; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; white-space:nowrap; outline:0px!important; background:0px 0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; font-size:10pt!important; min-height:auto!important"> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/api/v1/namespaces/</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">{namespace}</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/pods/</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">{name}</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/proxy/</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">{path:*}&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(0,130,0); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">#访问pod的某个服务接口</code> 
     </div> 
     <div style="margin:0px; padding:0px 1em 0px 0px; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; white-space:nowrap; outline:0px!important; background:0px 0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; font-size:10pt!important; min-height:auto!important"> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/api/v1/namespaces/</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">{namespace}</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/pods/</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">{name}</code> 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(199,37,78); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">/proxy</code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
      <code style="margin:0px; padding:0px; font-family:Consolas,&quot;Bitstream Vera Sans Mono&quot;,&quot;Courier New&quot;,Courier,monospace; color:rgb(0,130,0); background:none; border:0px; float:none; vertical-align:baseline; height:auto; width:auto; overflow:visible; font-size:10pt!important; outline:0px!important; position:static!important; left:auto!important; top:auto!important; right:auto!important; bottom:auto!important; line-height:1.1em!important; min-height:auto!important">#访问Pod</code> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

## 3.3. Service相关接口 ##

Pod的proxy接口的作用：在kubernetes集群之外访问某个pod容器的服务（HTTP服务），可以用Proxy API实现，这种场景多用于管理目的，比如逐一排查Service的Pod副本，检查哪些Pod的服务存在异常问题。

# 4. 集群功能模块之间的通信 #

kubernetes API Server作为集群的核心，负责集群各功能模块之间的通信，集群内各个功能模块通过API Server将信息存入etcd，当需要获取和操作这些数据时，通过API Server提供的REST接口（GET\\LIST\\WATCH方法）来实现，从而实现各模块之间的信息交互。

## 4.1. kubelet与API Server交互 ##

每个Node节点上的kubelet定期就会调用API Server的REST接口报告自身状态，API Server接收这些信息后，将节点状态信息更新到etcd中。kubelet也通过API Server的Watch接口监听Pod信息，从而对Node机器上的POD进行管理。

<table style="border-collapse:collapse; border-spacing:0px; background-color:transparent; max-width:100%; display:block; width:auto; overflow:auto; margin:0px"> 
 <thead style=""> 
  <tr style=""> 
   <th style="margin:0px; padding:7px 15px 7px 10px; text-align:left; vertical-align:top; border:1px solid rgb(221,221,221); background:100% 50% no-repeat rgb(240,240,240)"> 
    <div style="margin:0px; padding:0px">
      监听信息 
    </div> </th> 
   <th style="margin:0px; padding:7px 15px 7px 10px; text-align:left; vertical-align:top; border:1px solid rgb(221,221,221); background:100% 50% no-repeat rgb(240,240,240)"> 
    <div style="margin:0px; padding:0px">
      kubelet动作 
    </div> </th> 
   <th style="margin:0px; padding:7px 15px 7px 10px; text-align:left; vertical-align:top; border:1px solid rgb(221,221,221); background:100% 50% no-repeat rgb(240,240,240)"> 
    <div style="margin:0px; padding:0px">
      备注 
    </div> </th> 
  </tr> 
 </thead> 
 <tbody style=""> 
  <tr style=""> 
   <td style="margin:0px; padding:7px 10px; vertical-align:top; border:1px solid rgb(221,221,221)"> 新的POD副本被调度绑定到本节点</td> 
   <td style="margin:0px; padding:7px 10px; vertical-align:top; border:1px solid rgb(221,221,221)"> 执行POD对应的容器的创建和启动逻辑</td> 
   <td style="margin:0px; padding:7px 10px; vertical-align:top; border:1px solid rgb(221,221,221)"> &nbsp;</td> 
  </tr> 
  <tr style=""> 
   <td style="margin:0px; padding:7px 10px; vertical-align:top; border:1px solid rgb(221,221,221)"> POD对象被删除</td> 
   <td style="margin:0px; padding:7px 10px; vertical-align:top; border:1px solid rgb(221,221,221)"> 删除本节点上相应的POD容器</td> 
   <td style="margin:0px; padding:7px 10px; vertical-align:top; border:1px solid rgb(221,221,221)"> &nbsp;</td> 
  </tr> 
  <tr style=""> 
   <td colspan="1" style="margin:0px; padding:7px 10px; vertical-align:top; border:1px solid rgb(221,221,221)"> 修改POD信息</td> 
   <td colspan="1" style="margin:0px; padding:7px 10px; vertical-align:top; border:1px solid rgb(221,221,221)"> 修改本节点的POD容器</td> 
   <td colspan="1" style="margin:0px; padding:7px 10px; vertical-align:top; border:1px solid rgb(221,221,221)"> &nbsp;</td> 
  </tr> 
 </tbody> 
</table>

## 4.2. kube-controller-manager与API Server交互 ##

kube-controller-manager中的Node Controller模块通过API Server提供的Watch接口，实时监控Node的信息，并做相应处理。

## 4.3. kube-scheduler与API Server交互 ##

Scheduler通过API Server的Watch接口监听到新建Pod副本的信息后，它会检索所有符合该Pod要求的Node列表，开始执行Pod调度逻辑。调度成功后将Pod绑定到目标节点上。

## 4.4. 特别说明 ##

为了缓解各模块对API Server的访问压力，各功能模块都采用缓存机制来缓存数据，各功能模块定时从API Server获取指定的资源对象信息（LIST/WATCH方法），然后将信息保存到本地缓存，功能模块在某些情况下不直接访问API Server，而是通过访问缓存数据来间接访问API Server。

参考《kubernetes权威指南》

![Center 1][]

[原文链接][Link 1]

[Link 1]: http://click.aliyun.com/m/27085/
[http_blog.csdn.net_huwh_article_details_75675706]: http://blog.csdn.net/huwh_/article/details/75675706
[Center]: /images/20220611/bbfaf625ddbf41208f0c1f15eaf81af2.png
[https_kubernetes.io_docs_api-reference_v1.6]: https://kubernetes.io/docs/api-reference/v1.6/
[Kubernetes]: http://blog.csdn.net/huwh_/article/details/75808383
[https_github.com_kubernetes_client-go]: https://github.com/kubernetes/client-go
[Link 2]: http://lib.csdn.net/base/mysql
[yqgroup_service.aliyun.com]: mailto:yqgroup@service.aliyun.com
[Center 1]: /images/20220611/373a2b992ecd4f21bef34bfc534d5bf4.png