Karen Bradshaw
41 lines
2.5 KiB
Markdown
41 lines
2.5 KiB
Markdown
---
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title: 关键插件 Pod 的调度保证
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content_type: concept
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---
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<!-- overview -->
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<!--
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In addition to Kubernetes core components like api-server, scheduler, controller-manager running on a master machine
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there are a number of add-ons which, for various reasons, must run on a regular cluster node (rather than the Kubernetes master).
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Some of these add-ons are critical to a fully functional cluster, such as metrics-server, DNS, and UI.
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A cluster may stop working properly if a critical add-on is evicted (either manually or as a side effect of another operation like upgrade)
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and becomes pending (for example when the cluster is highly utilized and either there are other pending pods that schedule into the space
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vacated by the evicted critical add-on pod or the amount of resources available on the node changed for some other reason).
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-->
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除了在主机上运行的 Kubernetes 核心组件（如 api-server 、scheduler 、controller-manager）之外，还有许多插件，由于各种原因，
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必须在常规集群节点（而不是 Kubernetes 主节点）上运行。
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其中一些插件对于功能完备的群集至关重要，例如 Heapster、DNS 和 UI。
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如果关键插件被逐出（手动或作为升级等其他操作的副作用）或者变成挂起状态，群集可能会停止正常工作。
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关键插件进入挂起状态的例子有：集群利用率过高；被逐出的关键插件 Pod 释放了空间，但该空间被之前悬决的 Pod 占用；由于其它原因导致节点上可用资源的总量发生变化。
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<!-- body -->
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<!--
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### Marking pod as critical
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-->
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### 标记关键 Pod
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<!--
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To be considered critical, the pod has to run in the `kube-system` namespace (configurable via flag) and
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* Have the priorityClassName set as "system-cluster-critical" or "system-node-critical", the latter being the highest for entire cluster. Alternatively, you could add an annotation `scheduler.alpha.kubernetes.io/critical-pod` as key and empty string as value to your pod, but this annotation is deprecated as of version 1.13 and will be removed in 1.14.
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-->
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要将 pod 标记为关键性（critical），pod 必须在 kube-system 命名空间中运行（可通过参数配置）。
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同时，需要将 `priorityClassName` 设置为 `system-cluster-critical` 或 `system-node-critical` ，后者是整个群集的最高级别。
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或者，也可以为 Pod 添加名为 `scheduler.alpha.kubernetes.io/critical-pod`、值为空字符串的注解。
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不过，这一注解从 1.13 版本开始不再推荐使用，并将在 1.14 中删除。
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