271 lines
18 KiB
Markdown
271 lines
18 KiB
Markdown
---
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title: Kubernetes 是什么？
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content_type: concept
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description: >
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Kubernetes 是一个可移植的，可扩展的开源平台，用于管理容器化的工作负载和服务，方便了声明式配置和自动化。它拥有一个庞大且快速增长的生态系统。Kubernetes 的服务，支持和工具广泛可用。
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weight: 10
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card:
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name: concepts
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weight: 10
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---
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<!--
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reviewers:
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- bgrant0607
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- mikedanese
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title: What is Kubernetes
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content_type: concept
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weight: 10
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card:
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name: concepts
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weight: 10
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-->
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<!-- overview -->
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<!--
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This page is an overview of Kubernetes.
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-->
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此页面是 Kubernetes 的概述。
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<!-- body -->
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<!--
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Kubernetes is a portable, extensible, open-source platform for managing containerized workloads and services, that facilitates both declarative configuration and automation. It has a large, rapidly growing ecosystem. Kubernetes services, support, and tools are widely available.
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-->
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Kubernetes 是一个可移植的、可扩展的开源平台，用于管理容器化的工作负载和服务，可促进声明式配置和自动化。
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Kubernetes 拥有一个庞大且快速增长的生态系统。Kubernetes 的服务、支持和工具广泛可用。
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<!--
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The name Kubernetes originates from Greek, meaning helmsman or pilot. Google open-sourced the Kubernetes project in 2014. Kubernetes builds upon a [decade and a half of experience that Google has with running production workloads at scale](https://research.google/pubs/pub43438), combined with best-of-breed ideas and practices from the community.
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-->
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名称 **Kubernetes** 源于希腊语，意为“舵手”或“飞行员”。Google 在 2014 年开源了 Kubernetes 项目。
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Kubernetes 建立在 [Google 在大规模运行生产工作负载方面拥有十几年的经验](https://research.google/pubs/pub43438)
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的基础上，结合了社区中最好的想法和实践。
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<!--
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## Going back in time
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Let's take a look at why Kubernetes is so useful by going back in time.
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-->
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## 时光回溯
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让我们回顾一下为什么 Kubernetes 如此有用。
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<!--
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-->
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<!--
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**Traditional deployment era:**
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Early on, organizations ran applications on physical servers. There was no way to define resource boundaries for applications in a physical server, and this caused resource allocation issues. For example, if multiple applications run on a physical server, there can be instances where one application would take up most of the resources, and as a result, the other applications would underperform. A solution for this would be to run each application on a different physical server. But this did not scale as resources were underutilized, and it was expensive for organizations to maintain many physical servers.
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-->
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**传统部署时代：**
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早期，各个组织机构在物理服务器上运行应用程序。无法为物理服务器中的应用程序定义资源边界，这会导致资源分配问题。
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例如，如果在物理服务器上运行多个应用程序，则可能会出现一个应用程序占用大部分资源的情况，
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结果可能导致其他应用程序的性能下降。
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一种解决方案是在不同的物理服务器上运行每个应用程序，但是由于资源利用不足而无法扩展，
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并且维护许多物理服务器的成本很高。
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<!--
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**Virtualized deployment era:**
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As a solution, virtualization was introduced. It allows you to run multiple Virtual Machines (VMs) on a single physical server's CPU. Virtualization allows applications to be isolated between VMs and provides a level of security as the information of one application cannot be freely accessed by another application.
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-->
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**虚拟化部署时代：**
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作为解决方案，引入了虚拟化。虚拟化技术允许你在单个物理服务器的 CPU 上运行多个虚拟机（VM）。
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虚拟化允许应用程序在 VM 之间隔离，并提供一定程度的安全，因为一个应用程序的信息
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不能被另一应用程序随意访问。
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<!--
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Virtualization allows better utilization of resources in a physical server and allows better scalability because an application can be added or updated easily, reduces hardware costs, and much more.
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Each VM is a full machine running all the components, including its own operating system, on top of the virtualized hardware.
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-->
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虚拟化技术能够更好地利用物理服务器上的资源，并且因为可轻松地添加或更新应用程序
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而可以实现更好的可伸缩性，降低硬件成本等等。
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每个 VM 是一台完整的计算机，在虚拟化硬件之上运行所有组件，包括其自己的操作系统。
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<!--
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**Container deployment era:**
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Containers are similar to VMs, but they have relaxed isolation properties to share the Operating System (OS) among the applications. Therefore, containers are considered lightweight. Similar to a VM, a container has its own filesystem, CPU, memory, process space, and more. As they are decoupled from the underlying infrastructure, they are portable across clouds and OS distributions.
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-->
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**容器部署时代：**
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容器类似于 VM，但是它们具有被放宽的隔离属性，可以在应用程序之间共享操作系统（OS）。
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因此，容器被认为是轻量级的。容器与 VM 类似，具有自己的文件系统、CPU、内存、进程空间等。
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由于它们与基础架构分离，因此可以跨云和 OS 发行版本进行移植。
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<!--
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Containers are becoming popular because they have many benefits. Some of the container benefits are listed below:
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-->
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容器因具有许多优势而变得流行起来。下面列出的是容器的一些好处：
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<!--
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* Agile application creation and deployment: increased ease and efficiency of container image creation compared to VM image use.
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* Continuous development, integration, and deployment: provides for reliable and frequent container image build and deployment with quick and easy rollbacks (due to image immutability).
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* Dev and Ops separation of concerns: create application container images at build/release time rather than deployment time, thereby decoupling applications from infrastructure.
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* Observability not only surfaces OS-level information and metrics, but also application health and other signals.
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* Environmental consistency across development, testing, and production: Runs the same on a laptop as it does in the cloud.
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* Cloud and OS distribution portability: Runs on Ubuntu, RHEL, CoreOS, on-prem, Google Kubernetes Engine, and anywhere else.
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* Application-centric management: Raises the level of abstraction from running an OS on virtual hardware to running an application on an OS using logical resources.
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* Loosely coupled, distributed, elastic, liberated micro-services: applications are broken into smaller, independent pieces and can be deployed and managed dynamically – not a monolithic stack running on one big single-purpose machine.
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* Resource isolation: predictable application performance.
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* Resource utilization: high efficiency and density.
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-->
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* 敏捷应用程序的创建和部署：与使用 VM 镜像相比，提高了容器镜像创建的简便性和效率。
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* 持续开发、集成和部署：通过快速简单的回滚（由于镜像不可变性），支持可靠且频繁的
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容器镜像构建和部署。
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* 关注开发与运维的分离：在构建/发布时而不是在部署时创建应用程序容器镜像，
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从而将应用程序与基础架构分离。
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* 可观察性不仅可以显示操作系统级别的信息和指标，还可以显示应用程序的运行状况和其他指标信号。
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* 跨开发、测试和生产的环境一致性：在便携式计算机上与在云中相同地运行。
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* 跨云和操作系统发行版本的可移植性：可在 Ubuntu、RHEL、CoreOS、本地、
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Google Kubernetes Engine 和其他任何地方运行。
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* 以应用程序为中心的管理：提高抽象级别，从在虚拟硬件上运行 OS 到使用逻辑资源在
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OS 上运行应用程序。
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* 松散耦合、分布式、弹性、解放的微服务：应用程序被分解成较小的独立部分，
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并且可以动态部署和管理 - 而不是在一台大型单机上整体运行。
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* 资源隔离：可预测的应用程序性能。
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* 资源利用：高效率和高密度。
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<!--
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## Why you need Kubernetes and what can it do
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-->
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## 为什么需要 Kubernetes，它能做什么?
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<!--
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Containers are a good way to bundle and run your applications. In a production environment, you need to manage the containers that run the applications and ensure that there is no downtime. For example, if a container goes down, another container needs to start. Wouldn't it be easier if this behavior was handled by a system?
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-->
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容器是打包和运行应用程序的好方式。在生产环境中，你需要管理运行应用程序的容器，并确保不会停机。
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例如，如果一个容器发生故障，则需要启动另一个容器。如果系统处理此行为，会不会更容易？
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<!--
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That's how Kubernetes comes to the rescue! Kubernetes provides you with a framework to run distributed systems resiliently. It takes care of your scaling requirements, failover, deployment patterns, and more. For example, Kubernetes can easily manage a canary deployment for your system.
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-->
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这就是 Kubernetes 来解决这些问题的方法！
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Kubernetes 为你提供了一个可弹性运行分布式系统的框架。
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Kubernetes 会满足你的扩展要求、故障转移、部署模式等。
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例如，Kubernetes 可以轻松管理系统的 Canary 部署。
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<!--
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Kubernetes provides you with:
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-->
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Kubernetes 为你提供：
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<!--
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* **Service discovery and load balancing**
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Kubernetes can expose a container using the DNS name or using their own IP address. If traffic to a container is high, Kubernetes is able to load balance and distribute the network traffic so that the deployment is stable.
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-->
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* **服务发现和负载均衡**
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Kubernetes 可以使用 DNS 名称或自己的 IP 地址公开容器，如果进入容器的流量很大，
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Kubernetes 可以负载均衡并分配网络流量，从而使部署稳定。
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<!--
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* **Storage orchestration**
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Kubernetes allows you to automatically mount a storage system of your choice, such as local storages, public cloud providers, and more.
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-->
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* **存储编排**
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Kubernetes 允许你自动挂载你选择的存储系统，例如本地存储、公共云提供商等。
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<!--
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* **Automated rollouts and rollbacks**
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You can describe the desired state for your deployed containers using Kubernetes, and it can change the actual state to the desired state at a controlled rate. For example, you can automate Kubernetes to create new containers for your deployment, remove existing containers and adopt all their resources to the new container.
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-->
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* **自动部署和回滚**
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你可以使用 Kubernetes 描述已部署容器的所需状态，它可以以受控的速率将实际状态
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更改为期望状态。例如，你可以自动化 Kubernetes 来为你的部署创建新容器，
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删除现有容器并将它们的所有资源用于新容器。
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<!--
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* **Automatic bin packing**
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Kubernetes allows you to specify how much CPU and memory (RAM) each container needs. When containers have resource requests specified, Kubernetes can make better decisions to manage the resources for containers.
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-->
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* **自动完成装箱计算**
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Kubernetes 允许你指定每个容器所需 CPU 和内存（RAM）。
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当容器指定了资源请求时，Kubernetes 可以做出更好的决策来管理容器的资源。
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<!--
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* **Self-healing**
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Kubernetes restarts containers that fail, replaces containers, kills containers that don’t respond to your user-defined health check, and doesn’t advertise them to clients until they are ready to serve.
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-->
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* **自我修复**
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Kubernetes 重新启动失败的容器、替换容器、杀死不响应用户定义的
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运行状况检查的容器，并且在准备好服务之前不将其通告给客户端。
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<!--
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* **Secret and configuration management**
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Kubernetes lets you store and manage sensitive information, such as passwords, OAuth tokens, and ssh keys. You can deploy and update secrets and application configuration without rebuilding your container images, and without exposing secrets in your stack configuration.
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-->
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* **密钥与配置管理**
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Kubernetes 允许你存储和管理敏感信息，例如密码、OAuth 令牌和 ssh 密钥。
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你可以在不重建容器镜像的情况下部署和更新密钥和应用程序配置，也无需在堆栈配置中暴露密钥。
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<!--
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## What Kubernetes is not
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-->
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## Kubernetes 不是什么
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<!--
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Kubernetes is not a traditional, all-inclusive PaaS (Platform as a Service) system. Since Kubernetes operates at the container level rather than at the hardware level, it provides some generally applicable features common to PaaS offerings, such as deployment, scaling, load balancing, logging, and monitoring. However, Kubernetes is not monolithic, and these default solutions are optional and pluggable. Kubernetes provides the building blocks for building developer platforms, but preserves user choice and flexibility where it is important.
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-->
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Kubernetes 不是传统的、包罗万象的 PaaS（平台即服务）系统。
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由于 Kubernetes 在容器级别而不是在硬件级别运行，它提供了 PaaS 产品共有的一些普遍适用的功能，
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例如部署、扩展、负载均衡、日志记录和监视。
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但是，Kubernetes 不是单体系统，默认解决方案都是可选和可插拔的。
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Kubernetes 提供了构建开发人员平台的基础，但是在重要的地方保留了用户的选择和灵活性。
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<!--
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Kubernetes:
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-->
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Kubernetes：
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<!--
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* Does not limit the types of applications supported. Kubernetes aims to support an extremely diverse variety of workloads, including stateless, stateful, and data-processing workloads. If an application can run in a container, it should run great on Kubernetes.
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* Does not deploy source code and does not build your application. Continuous Integration, Delivery, and Deployment (CI/CD) workflows are determined by organization cultures and preferences as well as technical requirements.
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* Does not provide application-level services, such as middleware (for example, message buses), data-processing frameworks (for example, Spark), databases (for example, mysql), caches, nor cluster storage systems (for example, Ceph) as built-in services. Such components can run on Kubernetes, and/or can be accessed by applications running on Kubernetes through portable mechanisms, such as the Open Service Broker.
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-->
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* 不限制支持的应用程序类型。
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Kubernetes 旨在支持极其多种多样的工作负载，包括无状态、有状态和数据处理工作负载。
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如果应用程序可以在容器中运行，那么它应该可以在 Kubernetes 上很好地运行。
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* 不部署源代码，也不构建你的应用程序。
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持续集成(CI)、交付和部署（CI/CD）工作流取决于组织的文化和偏好以及技术要求。
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* 不提供应用程序级别的服务作为内置服务，例如中间件（例如，消息中间件）、
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数据处理框架（例如，Spark）、数据库（例如，mysql）、缓存、集群存储系统
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（例如，Ceph）。这样的组件可以在 Kubernetes 上运行，并且/或者可以由运行在
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Kubernetes 上的应用程序通过可移植机制（例如，
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[开放服务代理](https://openservicebrokerapi.org/)）来访问。
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<!--
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* Does not dictate logging, monitoring, or alerting solutions. It provides some integrations as proof of concept, and mechanisms to collect and export metrics.
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* Does not provide nor mandate a configuration language/system (for example, jsonnet). It provides a declarative API that may be targeted by arbitrary forms of declarative specifications.
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* Does not provide nor adopt any comprehensive machine configuration, maintenance, management, or self-healing systems.
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* Additionally, Kubernetes is not a mere orchestration system. In fact, it eliminates the need for orchestration. The technical definition of orchestration is execution of a defined workflow: first do A, then B, then C. In contrast, Kubernetes comprises a set of independent, composable control processes that continuously drive the current state towards the provided desired state. It shouldn’t matter how you get from A to C. Centralized control is also not required. This results in a system that is easier to use and more powerful, robust, resilient, and extensible.
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-->
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* 不要求日志记录、监视或警报解决方案。
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它提供了一些集成作为概念证明，并提供了收集和导出指标的机制。
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* 不提供或不要求配置语言/系统（例如 jsonnet），它提供了声明性 API，
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该声明性 API 可以由任意形式的声明性规范所构成。
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* 不提供也不采用任何全面的机器配置、维护、管理或自我修复系统。
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* 此外，Kubernetes 不仅仅是一个编排系统，实际上它消除了编排的需要。
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编排的技术定义是执行已定义的工作流程：首先执行 A，然后执行 B，再执行 C。
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相比之下，Kubernetes 包含一组独立的、可组合的控制过程，
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这些过程连续地将当前状态驱动到所提供的所需状态。
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如何从 A 到 C 的方式无关紧要，也不需要集中控制，这使得系统更易于使用
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且功能更强大、系统更健壮、更为弹性和可扩展。
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## {{% heading "whatsnext" %}}
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<!--
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* Take a look at the [Kubernetes Components](/docs/concepts/overview/components/)
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* Ready to [Get Started](/docs/setup/)?
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-->
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* 查阅 [Kubernetes 组件](/zh/docs/concepts/overview/components/)
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* 开始 [Kubernetes 入门](/zh/docs/setup/)?
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