[zh] sync job-with-pod-to-pod-communication.md
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---
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title: 带 Pod 间通信的 Job
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content_type: task
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min-kubernetes-server-version: v1.21
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weight: 30
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---
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<!--
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title: Job with Pod-to-Pod Communication
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content_type: task
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min-kubernetes-server-version: v1.21
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weight: 30
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-->
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<!-- overview -->
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<!--
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In this example, you will run a Job in [Indexed completion mode](/blog/2021/04/19/introducing-indexed-jobs/) configured such that
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the pods created by the Job can communicate with each other using pod hostnames rather than pod IP addresses.
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Pods within a Job might need to communicate among themselves. The user workload running in each pod could query the Kubernetes API server
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to learn the IPs of the other Pods, but it's much simpler to rely on Kubernetes' built-in DNS resolution.
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-->
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在此例中，你将以[索引完成模式](/blog/2021/04/19/introducing-indexed-jobs/)运行一个 Job，
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并通过配置使得该 Job 所创建的各 Pod 之间可以使用 Pod 主机名而不是 Pod IP 地址进行通信。
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某 Job 内的 Pod 之间可能需要通信。每个 Pod 中运行的用户工作负载可以查询 Kubernetes API
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服务器以获知其他 Pod 的 IP，但使用 Kubernetes 内置的 DNS 解析会更加简单。
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<!--
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Jobs in Indexed completion mode automatically set the pods' hostname to be in the format of
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`${jobName}-${completionIndex}`. You can use this format to deterministically build
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pod hostnames and enable pod communication *without* needing to create a client connection to
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the Kubernetes control plane to obtain pod hostnames/IPs via API requests.
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This configuration is useful
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for use cases where pod networking is required but you don't want to depend on a network
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connection with the Kubernetes API server.
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-->
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索引完成模式下的 Job 自动将 Pod 的主机名设置为 `${jobName}-${completionIndex}` 的格式。
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你可以使用此格式确定性地构建 Pod 主机名并启用 Pod 通信，无需创建到 Kubernetes
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控制平面的客户端连接来通过 API 请求获取 Pod 主机名/IP。
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此配置可用于需要 Pod 联网但不想依赖 Kubernetes API 服务器网络连接的使用场景。
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## {{% heading "prerequisites" %}}
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<!--
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You should already be familiar with the basic use of [Job](/docs/concepts/workloads/controllers/job/).
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-->
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你应该已熟悉了 [Job](/zh-cn/docs/concepts/workloads/controllers/job/) 的基本用法。
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{{< include "task-tutorial-prereqs.md" >}} {{< version-check >}}
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{{<note>}}
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<!--
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If you are using MiniKube or a similar tool, you may need to take
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[extra steps](https://minikube.sigs.k8s.io/docs/handbook/addons/ingress-dns/)
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to ensure you have DNS.
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-->
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如果你正在使用 MiniKube 或类似的工具，
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你可能需要采取[额外的步骤](https://minikube.sigs.k8s.io/docs/handbook/addons/ingress-dns/)来确保你拥有 DNS。
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{{</note>}}
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<!-- steps -->
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<!--
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## Starting a Job with Pod-to-Pod Communication
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To enable pod-to-pod communication using pod hostnames in a Job, you must do the following:
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-->
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## 启动带 Pod 间通信的 Job {#starting-a-job-with-pod-to-pod-communication}
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要在某 Job 中启用使用 Pod 主机名的 Pod 间通信，你必须执行以下操作：
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<!--
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1. Set up a [headless service](/docs/concepts/services-networking/service/#headless-services)
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with a valid label selector for the pods created by your Job. The headless service must be in the same namespace as
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the Job. One easy way to do this is to use the `job-name: <your-job-name>` selector, since the `job-name` label will be automatically added by Kubernetes. This configuration will trigger the DNS system to create records of the hostnames of
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the pods running your Job.
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2. Configure the headless service as subdomain service for the Job pods by including the following value in your Job template spec:
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-->
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1. 对于 Job 所创建的那些 Pod，
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使用一个有效的标签选择算符创建[无头服务](/zh-cn/docs/concepts/services-networking/service/#headless-services)。
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该无头服务必须位于与该 Job 相同的名字空间内。
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实现这一目的的一种简单的方式是使用 `job-name: <任务名称>` 作为选择算符，
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因为 `job-name` 标签将由 Kubernetes 自动添加。
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此配置将触发 DNS 系统为运行 Job 的 Pod 创建其主机名的记录。
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2. 通过将以下值包括到你的 Job 模板规约中，针对该 Job 的 Pod，将无头服务配置为其子域服务：
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```yaml
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subdomain: <无头服务的名称>
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```
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<!--
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### Example
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Below is a working example of a Job with pod-to-pod communication via pod hostnames enabled.
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The Job is completed only after all pods successfully ping each other using hostnames.
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-->
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### 示例 {#example}
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以下是启用通过 Pod 主机名来完成 Pod 间通信的 Job 示例。
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只有在使用主机名成功 ping 通所有 Pod 之后，此 Job 才会结束。
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{{<note>}}
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<!--
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In the Bash script executed on each pod in the example below, the pod hostnames can be prefixed
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by the namespace as well if the pod needs to be reached from outside the namespace.
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-->
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在以下示例中的每个 Pod 中执行的 Bash 脚本中，如果需要从名字空间外到达 Pod，
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Pod 主机名也可以带有该名字空间作为前缀。
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{{</note>}}
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```yaml
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apiVersion: v1
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kind: Service
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metadata:
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name: headless-svc
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spec:
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clusterIP: None # clusterIP 必须为 None 以创建无头服务
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selector:
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job-name: example-job # 必须与 Job 名称匹配
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---
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apiVersion: batch/v1
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kind: Job
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metadata:
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name: example-job
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spec:
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completions: 3
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parallelism: 3
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completionMode: Indexed
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template:
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spec:
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subdomain: headless-svc # 必须与 Service 名称匹配
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restartPolicy: Never
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containers:
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- name: example-workload
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image: bash:latest
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command:
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- bash
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- -c
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- |
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for i in 0 1 2
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do
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gotStatus="-1"
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wantStatus="0"
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while [ $gotStatus -ne $wantStatus ]
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do
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ping -c 1 example-job-${i}.headless-svc > /dev/null 2>&1
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gotStatus=$?
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if [ $gotStatus -ne $wantStatus ]; then
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echo "Failed to ping pod example-job-${i}.headless-svc, retrying in 1 second..."
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sleep 1
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fi
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done
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echo "Successfully pinged pod: example-job-${i}.headless-svc"
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done
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```
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<!--
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After applying the example above, reach each other over the network
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using: `<pod-hostname>.<headless-service-name>`. You should see output similar to the following:
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-->
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应用上述示例之后，使用 `<Pod 主机名>.<无头服务名>` 通过网络到达彼此。
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你应看到类似以下的输出：
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```shell
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kubectl logs example-job-0-qws42
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```
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```
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Failed to ping pod example-job-0.headless-svc, retrying in 1 second...
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Successfully pinged pod: example-job-0.headless-svc
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Successfully pinged pod: example-job-1.headless-svc
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Successfully pinged pod: example-job-2.headless-svc
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```
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{{<note>}}
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<!--
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Keep in mind that the `<pod-hostname>.<headless-service-name>` name format used
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in this example would not work with DNS policy set to `None` or `Default`.
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You can learn more about pod DNS policies [here](/docs/concepts/services-networking/dns-pod-service/#pod-s-dns-policy).
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-->
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谨记此例中使用的 `<Pod 主机名>.<无头服务名称>` 名称格式不适用于设置为 `None` 或 `Default` 的 DNS 策略。
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你可以在[此处](/zh-cn/docs/concepts/services-networking/dns-pod-service/#pod-s-dns-policy)了解有关
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Pod DNS 策略的更多信息。
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{{</note>}}
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