---
title: 通过聚合层扩展 Kubernetes API
content_type: concept
weight: 20
---

<!--
title: Extending the Kubernetes API with the aggregation layer
reviewers:
- lavalamp
- cheftako
- chenopis
content_type: concept
weight: 20
-->

<!-- overview -->

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The aggregation layer allows Kubernetes to be extended with additional APIs, beyond what is offered by the core Kubernetes APIs.
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使用聚合层（Aggregation Layer），用户可以通过额外的 API 扩展 Kubernetes，
而不局限于 Kubernetes 核心 API 提供的功能。

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The additional APIs can either be ready-made solutions such as [service-catalog](/docs/concepts/extend-kubernetes/service-catalog/), or APIs that you develop yourself.

The aggregation layer is different from [Custom Resources](/docs/concepts/extend-kubernetes/api-extension/custom-resources/), which are a way to make the {{< glossary_tooltip term_id="kube-apiserver" text="kube-apiserver" >}} recognise new kinds of object.
-->
这里的附加 API 可以是[服务目录](/zh/docs/concepts/extend-kubernetes/service-catalog/)
这类已经成熟的解决方案，也可以是你自己开发的 API。

聚合层不同于
[定制资源（Custom Resources）](/zh/docs/concepts/extend-kubernetes/api-extension/custom-resources/)。
后者的目的是让 {{< glossary_tooltip term_id="kube-apiserver" text="kube-apiserver" >}}
能够认识新的对象类别（Kind）。

<!-- body -->

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## Aggregation layer

The aggregation layer runs in-process with the kube-apiserver. Until an extension resource is registered, the aggregation layer will do nothing. To register an API, users must add an APIService object, which "claims" the URL path in the Kubernetes API. At that point, the aggregation layer will proxy anything sent to that API path (e.g. /apis/myextension.mycompany.io/v1/…) to the registered APIService.
-->
## 聚合层  {#aggregation-layer}

聚合层在 kube-apiserver 进程内运行。在扩展资源注册之前，聚合层不做任何事情。
要注册 API，用户必须添加一个 APIService 对象，用它来“申领” Kubernetes API 中的 URL 路径。
自此以后，聚合层将会把发给该 API 路径的所有内容（例如 `/apis/myextension.mycompany.io/v1/…`）
转发到已注册的 APIService。

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The most common way to implement the APIService is to run an *extension API server* in Pod(s) that run in your cluster. If you're using the extension API server to manage resources in your cluster, the extension API server (also written as "extension-apiserver") is typically paired with one or more {{< glossary_tooltip text="controllers" term_id="controller" >}}. The apiserver-builder library provides a skeleton for both extension API servers and the associated controller(s).
-->
APIService 的最常见实现方式是在集群中某 Pod 内运行 *扩展 API 服务器*。 
如果你在使用扩展 API 服务器来管理集群中的资源，该扩展 API 服务器（也被写成“extension-apiserver”）
一般需要和一个或多个{{< glossary_tooltip text="控制器" term_id="controller" >}}一起使用。
apiserver-builder 库同时提供构造扩展 API 服务器和控制器框架代码。


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### Response latency

Extension API servers should have low latency networking to and from the kube-apiserver.
Discovery requests are required to round-trip from the kube-apiserver in five seconds or less.

If your extension API server cannot achieve that latency requirement, consider making changes that let you meet it.
-->
### 反应延迟  {#response-latency}

扩展 API 服务器与 kube-apiserver 之间需要存在低延迟的网络连接。
发现请求需要在五秒钟或更短的时间内完成到 kube-apiserver 的往返。

如果你的扩展 API 服务器无法满足这一延迟要求，应考虑如何更改配置已满足需要。

## {{% heading "whatsnext" %}}

<!--
* To get the aggregator working in your environment, [configure the aggregation layer](/docs/tasks/access-kubernetes-api/configure-aggregation-layer/).
* Then, [setup an extension api-server](/docs/tasks/access-kubernetes-api/setup-extension-api-server/) to work with the aggregation layer.
* Also, learn how to [extend the Kubernetes API using Custom Resource Definitions](/docs/tasks/access-kubernetes-api/extend-api-custom-resource-definitions/).
* Read the specification for [APIService](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#apiservice-v1-apiregistration-k8s-io)
-->
* 阅读[配置聚合层](/zh/docs/tasks/extend-kubernetes/configure-aggregation-layer/) 文档，
  了解如何在自己的环境中启用聚合器。
* 接下来，了解[安装扩展 API 服务器](/zh/docs/tasks/extend-kubernetes/setup-extension-api-server/)，
  开始使用聚合层。
* 也可以学习怎样[使用自定义资源定义扩展 Kubernetes API](/zh/docs/tasks/extend-kubernetes/custom-resources/custom-resource-definitions/)。
* 阅读 [APIService](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#apiservice-v1-apiregistration-k8s-io) 的规范