248 lines
11 KiB
Markdown
248 lines
11 KiB
Markdown
---
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title: Operator 模式
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content_type: concept
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weight: 30
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---
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<!--
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title: Operator pattern
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content_type: concept
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weight: 30
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-->
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<!-- overview -->
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<!--
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Operators are software extensions to Kubernetes that make use of [custom
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resources](/docs/concepts/extend-kubernetes/api-extension/custom-resources/)
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to manage applications and their components. Operators follow
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Kubernetes principles, notably the [control loop](/docs/concepts/architecture/controller/).
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-->
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Operator 是 Kubernetes 的扩展软件，它利用
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[定制资源](/zh/docs/concepts/extend-kubernetes/api-extension/custom-resources/)
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管理应用及其组件。
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Operator 遵循 Kubernetes 的理念，特别是在[控制器](/zh/docs/concepts/architecture/controller/)
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方面。
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<!-- body -->
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<!--
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## Motivation
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The Operator pattern aims to capture the key aim of a human operator who
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is managing a service or set of services. Human operators who look after
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specific applications and services have deep knowledge of how the system
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ought to behave, how to deploy it, and how to react if there are problems.
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People who run workloads on Kubernetes often like to use automation to take
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care of repeatable tasks. The Operator pattern captures how you can write
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code to automate a task beyond what Kubernetes itself provides.
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-->
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## 初衷
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Operator 模式旨在捕获（正在管理一个或一组服务的）运维人员的关键目标。
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负责特定应用和 service 的运维人员，在系统应该如何运行、如何部署以及出现问题时如何处理等方面有深入的了解。
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在 Kubernetes 上运行工作负载的人们都喜欢通过自动化来处理重复的任务。
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Operator 模式会封装你编写的（Kubernetes 本身提供功能以外的）任务自动化代码。
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<!--
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## Operators in Kubernetes
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Kubernetes is designed for automation. Out of the box, you get lots of
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built-in automation from the core of Kubernetes. You can use Kubernetes
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to automate deploying and running workloads, *and* you can automate how
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Kubernetes does that.
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Kubernetes' {{< glossary_tooltip text="controllers" term_id="controller" >}}
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concept lets you extend the cluster's behaviour without modifying the code
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of Kubernetes itself.
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Operators are clients of the Kubernetes API that act as controllers for
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a [Custom Resource](/docs/concepts/extend-kubernetes/api-extension/custom-resources/).
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-->
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## Kubernetes 上的 Operator
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Kubernetes 为自动化而生。无需任何修改，你即可以从 Kubernetes 核心中获得许多内置的自动化功能。
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你可以使用 Kubernetes 自动化部署和运行工作负载， *甚至* 可以自动化 Kubernetes 自身。
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Kubernetes {{< glossary_tooltip text="控制器" term_id="controller" >}}
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使你无需修改 Kubernetes 自身的代码，即可以扩展集群的行为。
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Operator 是 Kubernetes API 的客户端，充当
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[定制资源](/zh/docs/concepts/extend-kubernetes/api-extension/custom-resources/)
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的控制器。
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<!--
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## An example Operator {#example}
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Some of the things that you can use an operator to automate include:
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* deploying an application on demand
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* taking and restoring backups of that application's state
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* handling upgrades of the application code alongside related changes such
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as database schemas or extra configuration settings
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* publishing a Service to applications that don't support Kubernetes APIs to
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discover them
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* simulating failure in all or part of your cluster to test its resilience
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* choosing a leader for a distributed application without an internal
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member election process
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-->
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## Operator 示例 {#example}
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使用 Operator 可以自动化的事情包括：
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* 按需部署应用
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* 获取/还原应用状态的备份
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* 处理应用代码的升级以及相关改动。例如，数据库 schema 或额外的配置设置
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* 发布一个 service，要求不支持 Kubernetes API 的应用也能发现它
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* 模拟整个或部分集群中的故障以测试其稳定性
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* 在没有内部成员选举程序的情况下，为分布式应用选择首领角色
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<!--
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What might an Operator look like in more detail? Here's an example in more
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detail:
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1. A custom resource named SampleDB, that you can configure into the cluster.
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2. A Deployment that makes sure a Pod is running that contains the
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controller part of the operator.
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3. A container image of the operator code.
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4. Controller code that queries the control plane to find out what SampleDB
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resources are configured.
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5. The core of the Operator is code to tell the API server how to make
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reality match the configured resources.
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* If you add a new SampleDB, the operator sets up PersistentVolumeClaims
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to provide durable database storage, a StatefulSet to run SampleDB and
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a Job to handle initial configuration.
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* If you delete it, the Operator takes a snapshot, then makes sure that
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the StatefulSet and Volumes are also removed.
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6. The operator also manages regular database backups. For each SampleDB
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resource, the operator determines when to create a Pod that can connect
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to the database and take backups. These Pods would rely on a ConfigMap
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and / or a Secret that has database connection details and credentials.
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7. Because the Operator aims to provide robust automation for the resource
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it manages, there would be additional supporting code. For this example,
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code checks to see if the database is running an old version and, if so,
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creates Job objects that upgrade it for you.
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-->
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想要更详细的了解 Operator？这儿有一个详细的示例：
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1. 有一个名为 SampleDB 的自定义资源，你可以将其配置到集群中。
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2. 一个包含 Operator 控制器部分的 Deployment，用来确保 Pod 处于运行状态。
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3. Operator 代码的容器镜像。
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4. 控制器代码，负责查询控制平面以找出已配置的 SampleDB 资源。
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5. Operator 的核心是告诉 API 服务器，如何使现实与代码里配置的资源匹配。
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* 如果添加新的 SampleDB，Operator 将设置 PersistentVolumeClaims 以提供
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持久化的数据库存储，设置 StatefulSet 以运行 SampleDB，并设置 Job
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来处理初始配置。
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* 如果你删除它，Operator 将建立快照，然后确保 StatefulSet 和 Volume 已被删除。
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6. Operator 也可以管理常规数据库的备份。对于每个 SampleDB 资源，Operator
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会确定何时创建（可以连接到数据库并进行备份的）Pod。这些 Pod 将依赖于
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ConfigMap 和/或具有数据库连接详细信息和凭据的 Secret。
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7. 由于 Operator 旨在为其管理的资源提供强大的自动化功能，因此它还需要一些
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额外的支持性代码。在这个示例中，代码将检查数据库是否正运行在旧版本上，
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如果是，则创建 Job 对象为你升级数据库。
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<!--
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## Deploying Operators
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The most common way to deploy an Operator is to add the
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Custom Resource Definition and its associated Controller to your cluster.
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The Controller will normally run outside of the
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{{< glossary_tooltip text="control plane" term_id="control-plane" >}},
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much as you would run any containerized application.
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For example, you can run the controller in your cluster as a Deployment.
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-->
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## 部署 Operator
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部署 Operator 最常见的方法是将自定义资源及其关联的控制器添加到你的集群中。
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跟运行容器化应用一样，控制器通常会运行在
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{{< glossary_tooltip text="控制平面" term_id="control-plane" >}} 之外。
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例如，你可以在集群中将控制器作为 Deployment 运行。
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<!--
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## Using an Operator {#using-operators}
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Once you have an Operator deployed, you'd use it by adding, modifying or
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deleting the kind of resource that the Operator uses. Following the above
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example, you would set up a Deployment for the Operator itself, and then:
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```shell
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kubectl get SampleDB # find configured databases
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kubectl edit SampleDB/example-database # manually change some settings
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```
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-->
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## 使用 Operator {#using-operators}
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部署 Operator 后，你可以对 Operator 所使用的资源执行添加、修改或删除操作。
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按照上面的示例，你将为 Operator 本身建立一个 Deployment，然后：
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```shell
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kubectl get SampleDB # 查找所配置的数据库
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kubectl edit SampleDB/example-database # 手动修改某些配置
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```
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<!--
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…and that's it! The Operator will take care of applying the changes as well as keeping the existing service in good shape.
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-->
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可以了！Operator 会负责应用所作的更改并保持现有服务处于良好的状态。
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<!--
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## Writing your own Operator {#writing-operator}
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-->
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## 编写你自己的 Operator {#writing-operator}
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<!--
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If there isn't an Operator in the ecosystem that implements the behavior you
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want, you can code your own.
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You also implement an Operator (that is, a Controller) using any language / runtime
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that can act as a [client for the Kubernetes API](/docs/reference/using-api/client-libraries/).
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-->
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如果生态系统中没可以实现你目标的 Operator，你可以自己编写代码。
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你还可以使用任何支持 [Kubernetes API 客户端](/zh/docs/reference/using-api/client-libraries/)
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的语言或运行时来实现 Operator（即控制器）。
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<!--
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Following are a few libraries and tools you can use to write your own cloud native
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Operator.
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{{% thirdparty-content %}}
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* [kubebuilder](https://book.kubebuilder.io/)
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* [KUDO](https://kudo.dev/) (Kubernetes Universal Declarative Operator)
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* [Metacontroller](https://metacontroller.app/) along with WebHooks that
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you implement yourself
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* [Operator Framework](https://operatorframework.io)
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-->
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以下是一些库和工具，你可用于编写自己的云原生 Operator。
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{{% thirdparty-content %}}
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* [kubebuilder](https://book.kubebuilder.io/)
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* [KUDO](https://kudo.dev/) (Kubernetes 通用声明式 Operator)
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* [Metacontroller](https://metacontroller.app/)，可与 Webhooks 结合使用，以实现自己的功能。
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* [Operator Framework](https://operatorframework.io)
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## {{% heading "whatsnext" %}}
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<!--
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* Learn more about [Custom Resources](/docs/concepts/extend-kubernetes/api-extension/custom-resources/)
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* Find ready-made operators on [OperatorHub.io](https://operatorhub.io/) to suit your use case
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* [Publish](https://operatorhub.io/) your operator for other people to use
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* Read [CoreOS' original article](https://web.archive.org/web/20170129131616/https://coreos.com/blog/introducing-operators.html) that introduced the Operator pattern (this is an archived version of the original article).
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* Read an [article](https://cloud.google.com/blog/products/containers-kubernetes/best-practices-for-building-kubernetes-operators-and-stateful-apps) from Google Cloud about best practices for building Operators
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-->
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* 详细了解 [定制资源](/zh/docs/concepts/extend-kubernetes/api-extension/custom-resources/)
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* 在 [OperatorHub.io](https://operatorhub.io/) 上找到现成的、适合你的 Operator
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* [发布](https://operatorhub.io/)你的 Operator，让别人也可以使用
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* 阅读 [CoreOS 原始文章](https://web.archive.org/web/20170129131616/https://coreos.com/blog/introducing-operators.html)，它介绍了 Operator 模式（这是一个存档版本的原始文章）。
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* 阅读这篇来自谷歌云的关于构建 Operator 最佳实践的
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[文章](https://cloud.google.com/blog/products/containers-kubernetes/best-practices-for-building-kubernetes-operators-and-stateful-apps)
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