Kubernetes 简明教程

Kubernetes - Jobs

作业的主要功能是创建一或更多个 Pod 并跟踪 Pod 的成功。它们确保成功完成指定数量的 Pod。当指定数量的成功 Pod 运行完成时，则作业被视为完成。

The main function of a job is to create one or more pod and tracks about the success of pods. They ensure that the specified number of pods are completed successfully. When a specified number of successful run of pods is completed, then the job is considered complete.

Creating a Job

使用以下命令创建作业 −

Use the following command to create a job −

apiVersion: v1
kind: Job ------------------------> 1
metadata:
   name: py
   spec:
   template:
      metadata
      name: py -------> 2
      spec:
         containers:
            - name: py ------------------------> 3
            image: python----------> 4
            command: ["python", "SUCCESS"]
            restartPocliy: Never --------> 5

在以上的代码中，我们已经定义了 −

In the above code, we have defined −

  1. kind: Job → We have defined the kind as Job which will tell kubectl that the yaml file being used is to create a job type pod.

  2. Name:py → This is the name of the template that we are using and the spec defines the template.

  3. name: py → we have given a name as py under container spec which helps to identify the Pod which is going to be created out of it.

  4. Image: python → the image which we are going to pull to create the container which will run inside the pod.

  5. *restartPolicy: Never →*This condition of image restart is given as never which means that if the container is killed or if it is false, then it will not restart itself.

我们将使用保存为 py.yaml 名称的 yaml 通过以下命令创建作业。

We will create the job using the following command with yaml which is saved with the name py.yaml.

$ kubectl create –f py.yaml

以上命令将创建作业。如果你要检查作业状态，可以使用以下命令。

The above command will create a job. If you want to check the status of a job, use the following command.

$ kubectl describe jobs/py

以上命令将创建作业。如果你要检查作业状态，可以使用以下命令。

The above command will create a job. If you want to check the status of a job, use the following command.

Scheduled Job

Kubernetes 中的计划作业使用 Cronetes ，它获取 Kubernetes 作业并在 Kubernetes 集群中启动它们。

Scheduled job in Kubernetes uses Cronetes, which takes Kubernetes job and launches them in Kubernetes cluster.

  1. Scheduling a job will run a pod at a specified point of time.

  2. A parodic job is created for it which invokes itself automatically.

Note − 计划作业的功能受 1.4 版支持，并且在启动 API 服务器时通过传递 –runtime-config=batch/v2alpha1 打开 batch/v2alpha1 API。

Note − The feature of a scheduled job is supported by version 1.4 and the betch/v2alpha 1 API is turned on by passing the –runtime-config=batch/v2alpha1 while bringing up the API server.

我们将使用与创建作业相同的 yaml，并使其成为计划作业。

We will use the same yaml which we used to create the job and make it a scheduled job.

apiVersion: v1
kind: Job
metadata:
   name: py
spec:
   schedule: h/30 * * * * ? -------------------> 1
   template:
      metadata
         name: py
      spec:
         containers:
         - name: py
         image: python
         args:
/bin/sh -------> 2
-c
ps –eaf ------------> 3
restartPocliy: OnFailure

在以上的代码中，我们已经定义了 −

In the above code, we have defined −

  1. schedule: h/30 * * * * ? → To schedule the job to run in every 30 minutes.

  2. /bin/sh: This will enter in the container with /bin/sh

  3. ps –eaf → Will run ps -eaf command on the machine and list all the running process inside a container.

当我们尝试在指定时间点构建和运行一组任务，然后再完成进程时，此计划作业概念非常有用。

This scheduled job concept is useful when we are trying to build and run a set of tasks at a specified point of time and then complete the process.