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* Update dns-horizontal-autoscaling.md * Update dns-horizontal-autoscaling.md * Update dns-horizontal-autoscaling.md
486 lines
13 KiB
Markdown
486 lines
13 KiB
Markdown
---
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title: 自动伸缩集群中的 DNS 服务
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content_template: templates/task
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---
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<!--
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---
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title: Autoscale the DNS Service in a Cluster
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content_template: templates/task
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---
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-->
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{{% capture overview %}}
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<!--
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This page shows how to enable and configure autoscaling of the DNS service in a
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Kubernetes cluster.
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-->
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此页面展示如何启用和配置集群中 DNS 服务的自动伸缩。
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{{% /capture %}}
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{{% capture prerequisites %}}
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<!--
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* {{< include "task-tutorial-prereqs.md" >}} {{< version-check >}}
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* Make sure the [DNS feature](/docs/concepts/services-networking/dns-pod-service/) itself is enabled.
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* Kubernetes version 1.4.0 or later is recommended.
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-->
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* {{< include "task-tutorial-prereqs.md" >}} {{< version-check >}}
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* 确保 [DNS 特性](/docs/concepts/services-networking/dns-pod-service/)是启用的。
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* 推荐使用 Kubernetes 1.4.0 或更高版本。
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{{% /capture %}}
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{{% capture steps %}}
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<!--
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## Determining whether DNS horizontal autoscaling is already enabled
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-->
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## 确定 DNS 水平自动伸缩是否已经启用
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<!--
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List the Deployments in your cluster in the kube-system namespace:
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-->
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列出集群中命名空间 kube-system 下的 Deployment：
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kubectl get deployment --namespace=kube-system
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<!--
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The output is similar to this:
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-->
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输出类似：
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NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
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...
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dns-autoscaler 1 1 1 1 ...
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...
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<!--
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If you see "dns-autoscaler" in the output, DNS horizontal autoscaling is
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already enabled, and you can skip to
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[Tuning autoscaling parameters](#tuning-autoscaling-parameters).
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-->
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如果在输出中看到 `dns-autoscaler`，则表示已启用 DNS 水平自动缩放，
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可以跳过阅读[优化自动缩放参数](#tuning-autoscaling-parameters)章节。
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<!--
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## Getting the name of your DNS Deployment or ReplicationController
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-->
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## 获取 DNS Deployment 名或 ReplicationController 名
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<!--
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List the Deployments in your cluster in the kube-system namespace:
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-->
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列出集群中命名空间 kube-system 下的 Deployment：
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kubectl get deployment --namespace=kube-system
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<!--
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The output is similar to this:
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->
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输出类似：
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NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
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...
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coredns 2 2 2 2 ...
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...
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<!--
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In Kubernetes versions earlier than 1.12, the DNS Deployment was called "kube-dns".
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-->
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在早于 1.12 的 Kubernetes 版本中，DNS Deployment 称之为 `kube-dns`。
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<!--
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In Kubernetes versions earlier than 1.5 DNS was implemented using a
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ReplicationController instead of a Deployment. So if you don't see kube-dns,
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or a similar name, in the preceding output, list the ReplicationControllers in
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your cluster in the kube-system namespace:
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-->
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在 Kubernetes 1.5 之前的版本中，DNS 是使用 ReplicationController 而不是 Deployment 来实现的。
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因此，如果在前面的输出中没有看到 kube-dns 或类似的名称，请在 kube-system 名称空间中列出集群中的 ReplicationControllers:
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kubectl get rc --namespace=kube-system
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<!--
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The output is similar to this:
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-->
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输出类似：
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NAME DESIRED CURRENT READY AGE
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...
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kube-dns-v20 1 1 1 ...
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...
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<!--
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## Determining your scale target
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-->
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## 确定规模目标
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<!--
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If you have a DNS Deployment, your scale target is:
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-->
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如果是 DNS Deployment，则伸缩目标是：
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Deployment/<your-deployment-name>
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<!--
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where <dns-deployment-name> is the name of your DNS Deployment. For example, if
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your DNS Deployment name is coredns, your scale target is Deployment/coredns.
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-->
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其中，<dns-deployment-name> 是 DNS Deployment 的名称。
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例如，如果 DNS Deployment 名是 coredns，
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则伸缩目标是 Deployment/coredns。
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<!--
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If you have a DNS ReplicationController, your scale target is:
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-->
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如果是 DNS ReplicationController，则伸缩目标是:
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ReplicationController/<your-rc-name>
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<!--
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where <your-rc-name> is the name of your DNS ReplicationController. For example,
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if your DNS ReplicationController name is kube-dns-v20, your scale target is
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ReplicationController/kube-dns-v20.
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-->
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其中，<your-rc-name> 是 DNS ReplicationController 的名称。
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例如，如果 DNS ReplicationController 的名称为 kube-dns-v20，则伸缩目标是 ReplicationControlle/kube-dns-v20。
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<!--
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## Enabling DNS horizontal autoscaling
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-->
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## 启用 DNS 水平自动扩缩
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<!--
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In this section, you create a Deployment. The Pods in the Deployment run a
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container based on the `cluster-proportional-autoscaler-amd64` image.
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-->
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在本节中，您将创建一个 Deployment。Deployment 中的 Pod 根据 `cluster-proportional-autoscaler-amd64` 镜像运行容器。
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<!--
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Create a file named `dns-horizontal-autoscaler.yaml` with this content:
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-->
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创建一个名为 `dns-horizontal-autoscaler.yaml` 的文件内容如下:
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{{< codenew file="admin/dns/dns-horizontal-autoscaler.yaml" >}}
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<!--
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In the file, replace `<SCALE_TARGET>` with your scale target.
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-->
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在文件中，将 `<SCALE_TARGET>` 替换为扩缩目标。
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<!--
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Go to the directory that contains your configuration file, and enter this
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command to create the Deployment:
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-->
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转至包含配置文件的目录，然后输入以下命令以创建 Deployment：
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kubectl create -f dns-horizontal-autoscaler.yaml
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<!--
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The output of a successful command is:
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-->
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运行成功后的输出结果为：
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deployment.apps/kube-dns-autoscaler created
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<!--
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DNS horizontal autoscaling is now enabled.
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-->
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现在启用了 DNS 水平自动扩缩。
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<!--
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## Tuning autoscaling parameters
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-->
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## 调优自动扩缩参数
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<!--
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Verify that the dns-autoscaler ConfigMap exists:
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-->
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验证 dns-autoscaler ConfigMap 存在:
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kubectl get configmap --namespace=kube-system
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<!--
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The output is similar to this:
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-->
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输出类似：
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NAME DATA AGE
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...
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dns-autoscaler 1 ...
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...
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<!--
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Modify the data in the ConfigMap:
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-->
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修改 ConfigMap 中的数据：
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kubectl edit configmap dns-autoscaler --namespace=kube-system
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<!--
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Look for this line:
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-->
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寻找这一行：
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linear: '{"coresPerReplica":256,"min":1,"nodesPerReplica":16}'
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<!--
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Modify the fields according to your needs. The "min" field indicates the
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minimal number of DNS backends. The actual number of backends number is
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calculated using this equation:
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-->
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根据需要修改字段。`min` 字段表示 DNS 后端的最小数量。实际后端数的计算公式为：
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replicas = max( ceil( cores * 1/coresPerReplica ) , ceil( nodes * 1/nodesPerReplica ) )
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<!--
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Note that the values of both `coresPerReplica` and `nodesPerReplica` are
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integers.
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-->
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注意，`coresPerReplica` 和 `nodesPerReplica` 的值都是整数。
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<!--
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The idea is that when a cluster is using nodes that have many cores,
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`coresPerReplica` dominates. When a cluster is using nodes that have fewer
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cores, `nodesPerReplica` dominates.
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-->
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其思想是，当集群使用具有多个核心的节点时，`coresPerReplica` 占主导地位。
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当集群使用内核较少的节点时，`nodesPerReplica` 占主导地位。
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<!--
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There are other supported scaling patterns. For details, see
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[cluster-proportional-autoscaler](https://github.com/kubernetes-incubator/cluster-proportional-autoscaler).
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-->
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还有其他受支持的扩展模式。有关详细信息，请参见 [cluster-proportion -autoscaler](https://github.com/kubernetes-incubator/cluster-proportional-autoscaler)。
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<!--
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## Disable DNS horizontal autoscaling
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-->
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## 禁用 DNS 水平自动扩缩
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<!--
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There are a few options for tuning DNS horizontal autoscaling. Which option to
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use depends on different conditions.
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-->
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有一些选项可用于调优 DNS 水平自动扩缩。使用哪个选项取决于不同的条件。
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<!--
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### Option 1: Scale down the dns-autoscaler deployment to 0 replicas
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-->
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### 选项 1：将 dns-autoscaler deployment 降低到 0 个副本
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<!--
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This option works for all situations. Enter this command:
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-->
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此选项适用于所有情况。输入这个命令：
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kubectl scale deployment --replicas=0 dns-autoscaler --namespace=kube-system
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<!--
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The output is:
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-->
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输出是：
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deployment.extensions/dns-autoscaler scaled
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<!--
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Verify that the replica count is zero:
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-->
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验证副本计数是否为零：
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kubectl get deployment --namespace=kube-system
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<!--
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The output displays 0 in the DESIRED and CURRENT columns:
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-->
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输出在 DESIRED 和 CURRENT 列中显示 0：
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NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
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...
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dns-autoscaler 0 0 0 0 ...
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...
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<!--
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### Option 2: Delete the dns-autoscaler deployment
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-->
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### 选项 2：删除 dns-autoscaler deployment
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<!--
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This option works if dns-autoscaler is under your own control, which means
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no one will re-create it:
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-->
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如果 dns-autoscaler 在您自己的控制之下，则此选项有效，这意味着没有人会重新创建它：
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kubectl delete deployment dns-autoscaler --namespace=kube-system
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<!--
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The output is:
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-->
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输出是：
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deployment.extensions "dns-autoscaler" deleted
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<!--
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### Option 3: Delete the dns-autoscaler manifest file from the master node
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-->
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### 选项 3：从主节点中删除 dns-autoscaler 清单文件
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<!--
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This option works if dns-autoscaler is under control of the
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[Addon Manager](https://git.k8s.io/kubernetes/cluster/addons/README.md)'s
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control, and you have write access to the master node.
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-->
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此选项可行的前提是，dns-autoscaler 在[附加组件管理器](https://git.k8s.io/kubernetes/cluster/addons/README.md) 的控制之下，
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并且有对主节点的写访问权。
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<!--
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Sign in to the master node and delete the corresponding manifest file.
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The common path for this dns-autoscaler is:
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-->
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登录主节点并删除相应的清单文件。这个 dns-autoscaler 的通用路径是：
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/etc/kubernetes/addons/dns-horizontal-autoscaler/dns-horizontal-autoscaler.yaml
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<!--
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After the manifest file is deleted, the Addon Manager will delete the
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dns-autoscaler Deployment.
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-->
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删除清单文件后，附加组件管理器将删除 dns-autoscaler Deployment。
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{{% /capture %}}
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{{% capture discussion %}}
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<!--
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## Understanding how DNS horizontal autoscaling works
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-->
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了解 DNS 水平自动缩放的工作原理
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<!--
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* The cluster-proportional-autoscaler application is deployed separately from
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the DNS service.
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* An autoscaler Pod runs a client that polls the Kubernetes API server for the
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number of nodes and cores in the cluster.
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* A desired replica count is calculated and applied to the DNS backends based on
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the current schedulable nodes and cores and the given scaling parameters.
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* The scaling parameters and data points are provided via a ConfigMap to the
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autoscaler, and it refreshes its parameters table every poll interval to be up
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to date with the latest desired scaling parameters.
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* Changes to the scaling parameters are allowed without rebuilding or restarting
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the autoscaler Pod.
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* The autoscaler provides a controller interface to support two control
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patterns: *linear* and *ladder*.
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-->
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* 集群比例自动伸缩器应用程序与 DNS 服务分开部署。
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* 一个自动伸缩 Pod 运行一个客户端，该客户端轮询 Kubernetes API 服务器以获得集群中的节点和核心的数量。
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* 根据当前可调度节点和核心以及给定的缩放参数，计算并应用所需的副本计数到 DNS 后端。
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* 缩放参数和数据点是通过 ConfigMap 提供给 autoscaler 的，它会在每个轮询间隔刷新参数表，以更新所需的最新缩放参数。
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* 允许在不重新构建或重新启动自动缩放Pod的情况下更改缩放参数。
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* autoscaler 提供了一个控制器接口来支持两种控制模式：*linear* 和 *ladder*。
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<!--
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## Future enhancements
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-->
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## 未来的改进
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<!--
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Control patterns, in addition to linear and ladder, that consider custom metrics
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are under consideration as a future development.
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-->
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除了线性和梯形之外，未来将考虑自定义度量的控制模式。
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<!--
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Scaling of DNS backends based on DNS-specific metrics is under consideration as
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a future development. The current implementation, which uses the number of nodes
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and cores in cluster, is limited.
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-->
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基于 DNS 特定指标的 DNS 后端扩展正在考虑作为未来发展。当前实现使用集群中的节点和核心数量是有限的。
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<!--
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Support for custom metrics, similar to that provided by
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[Horizontal Pod Autoscaling](/docs/tasks/run-application/horizontal-pod-autoscale/),
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is under consideration as a future development.
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-->
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未来将考虑支持类似于[水平 Pod 自动伸缩](/docs/tasks/run-application/horizontal-pod-autoscale/)
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{{% /capture %}}
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{{% capture whatsnext %}}
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<!--
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Learn more about the
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[implementation of cluster-proportional-autoscaler](https://github.com/kubernetes-incubator/cluster-proportional-autoscaler).
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-->
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了解更多关于[实施 of cluster-proportional-autoscaler](https://github.com/kubernetes-incubator/cluster-proportional-autoscaler)。
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{{% /capture %}}
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