[zh] sync job-with-pod-to-pod-communication.md

Author: windsonsea

content/zh-cn/docs/tasks/job/job-with-pod-to-pod-communication.md

@@ -0,0 +1,188 @@
+---
+title: 带 Pod 间通信的 Job
+content_type: task
+min-kubernetes-server-version: v1.21
+weight: 30
+---
+<!--
+title: Job with Pod-to-Pod Communication
+content_type: task
+min-kubernetes-server-version: v1.21
+weight: 30
+-->
+
+<!-- overview -->
+
+<!--
+In this example, you will run a Job in [Indexed completion mode](/blog/2021/04/19/introducing-indexed-jobs/) configured such that
+the pods created by the Job can communicate with each other using pod hostnames rather than pod IP addresses.
+
+Pods within a Job might need to communicate among themselves. The user workload running in each pod could query the Kubernetes API server
+to learn the IPs of the other Pods, but it's much simpler to rely on Kubernetes' built-in DNS resolution.
+-->
+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，
+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。
+
+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
+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。
+
+<!--
+Jobs in Indexed completion mode automatically set the pods' hostname to be in the format of
+`${jobName}-${completionIndex}`. You can use this format to deterministically build
+pod hostnames and enable pod communication *without* needing to create a client connection to
+the Kubernetes control plane to obtain pod hostnames/IPs via API requests. 
+
+This configuration is useful
+for use cases where pod networking is required but you don't want to depend on a network 
+connection with the Kubernetes API server.
+-->
+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。
+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
+控制平面的客户端连接来通过 API 请求获取 Pod 主机名/IP。
+
+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。
+
+## {{% heading "prerequisites" %}}
+
+<!--
+You should already be familiar with the basic use of [Job](/docs/concepts/workloads/controllers/job/).
+-->
+你应该已熟悉了 [Job](/zh-cn/docs/concepts/workloads/controllers/job/) 的基本用法。
+
+{{< include "task-tutorial-prereqs.md" >}} {{< version-check >}}
+
+{{<note>}}
+<!--
+If you are using MiniKube or a similar tool, you may need to take
+[extra steps](https://minikube.sigs.k8s.io/docs/handbook/addons/ingress-dns/)
+to ensure you have DNS.
+-->
+如果你正在使用 MiniKube 或类似的工具，
+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。
+{{</note>}}
+
+<!-- steps -->
+
+<!--
+## Starting a Job with Pod-to-Pod Communication
+
+To enable pod-to-pod communication using pod hostnames in a Job, you must do the following:
+-->
+## 启动带 Pod 间通信的 Job   {#starting-a-job-with-pod-to-pod-communication}
+
+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：
+
+<!--
+1. Set up a [headless service](/docs/concepts/services-networking/service/#headless-services)
+with a valid label selector for the pods created by your Job. The headless service must be in the same namespace as 
+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 
+the pods running your Job.
+
+2. Configure the headless service as subdomain service for the Job pods by including the following value in your Job template spec:
+-->
+1. 对于 Job 所创建的那些 Pod，
+   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)。
+   该无头服务必须位于与该 Job 相同的名字空间内。
+   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，
+   因为 `job-name` 标签将由 Kubernetes 自动添加。
+   此配置将触发 DNS 系统为运行 Job 的 Pod 创建其主机名的记录。
+
+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：
+
+   ```yaml
+   subdomain: <无头服务的名称>
+   ```
+
+<!--
+### Example 
+Below is a working example of a Job with pod-to-pod communication via pod hostnames enabled.
+The Job is completed only after all pods successfully ping each other using hostnames.
+-->
+### 示例    {#example}
+
+以下是启用通过 Pod 主机名来完成 Pod 间通信的 Job 示例。
+只有在使用主机名成功 ping 通所有 Pod 之后，此 Job 才会结束。
+
+{{<note>}}
+<!--
+In the Bash script executed on each pod in the example below, the pod hostnames can be prefixed
+by the namespace as well  if the pod needs to be reached from outside the namespace.
+-->
+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，
+Pod 主机名也可以带有该名字空间作为前缀。
+{{</note>}}
+
+```yaml
+apiVersion: v1
+kind: Service
+metadata:
+  name: headless-svc
+spec:
+  clusterIP: None # clusterIP 必须为 None 以创建无头服务
+  selector:
+    job-name: example-job # 必须与 Job 名称匹配
+---
+apiVersion: batch/v1
+kind: Job
+metadata:
+  name: example-job
+spec:
+  completions: 3
+  parallelism: 3
+  completionMode: Indexed
+  template:
+    spec:
+      subdomain: headless-svc # 必须与 Service 名称匹配
+      restartPolicy: Never
+      containers:
+      - name: example-workload
+        image: bash:latest
+        command:
+        - bash
+        - -c
+        - |
+          for i in 0 1 2
+          do
+            gotStatus="-1"
+            wantStatus="0"             
+            while [ $gotStatus -ne $wantStatus ]
+            do                                       
+              ping -c 1 example-job-${i}.headless-svc > /dev/null 2>&1
+              gotStatus=$?                
+              if [ $gotStatus -ne $wantStatus ]; then
+                echo "Failed to ping pod example-job-${i}.headless-svc, retrying in 1 second..."
+                sleep 1
+              fi
+            done                                                         
+            echo "Successfully pinged pod: example-job-${i}.headless-svc"
+          done
+```
+
+<!--
+After applying the example above, reach each other over the network
+using: `<pod-hostname>.<headless-service-name>`. You should see output similar to the following:
+-->
+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。
+你应看到类似以下的输出：
+
+```shell
+kubectl logs example-job-0-qws42
+```
+
+```
+Failed to ping pod example-job-0.headless-svc, retrying in 1 second...
+Successfully pinged pod: example-job-0.headless-svc
+Successfully pinged pod: example-job-1.headless-svc
+Successfully pinged pod: example-job-2.headless-svc
+```
+
+{{<note>}}
+<!--
+Keep in mind that the `<pod-hostname>.<headless-service-name>` name format used
+in this example would not work with DNS policy set to `None` or `Default`.
+You can learn more about pod DNS policies [here](/docs/concepts/services-networking/dns-pod-service/#pod-s-dns-policy).
+-->
+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。
+你可以在[此处](/zh-cn/docs/concepts/services-networking/dns-pod-service/#pod-s-dns-policy)了解有关
+Pod DNS 策略的更多信息。
+{{</note>}}