[[["易于理解","easyToUnderstand","thumb-up"],["解决了我的问题","solvedMyProblem","thumb-up"],["其他","otherUp","thumb-up"]],[["很难理解","hardToUnderstand","thumb-down"],["信息或示例代码不正确","incorrectInformationOrSampleCode","thumb-down"],["没有我需要的信息/示例","missingTheInformationSamplesINeed","thumb-down"],["翻译问题","translationIssue","thumb-down"],["其他","otherDown","thumb-down"]],["最后更新时间 (UTC):2025-09-04。"],[],[],null,["# Tasks\n\nAbout Tasks\n-----------\n\nIn contrast to Apps (long-running processes), Tasks run for a finite amount of time and then stops. Tasks run in their own containers based on configuration on the parent App, and it could be configured to use limited resources (e.g. CPU/memory/ephermeral disk storage).\n\nUse Cases for Tasks\n-------------------\n\n- Migrating a database\n- Running a batch job (scheduled/unscheduled)\n- Sending an email\n- Transforming data (ETL)\n- Processing data (upload/backup/download)\n\nHow Tasks work\n--------------\n\nTasks are executed asynchronously and run independently from the parent App or other Tasks running on the same App. An App created for running Tasks does not have routes created or assigned, and the **Run** lifecycle is skipped. The **Source code upload** and **Build** lifecycles still proceed and result in a container image used for running Tasks after pushing the App (see App lifecycles at [Deploying an Application](../how-to/deploying-an-app)).\n\nThe lifecycle of a Task is as follows:\n\n1. You push an App for running tasks with the `kf push APP_NAME --task` command.\n2. You run a Task on the App with the `kf run-task APP_NAME` command. Task inherits the environment variables, service bindings, resource allocation, start-up command, and security groups bound to the App.\n3. Kf creates a Tekton [PipelineRun](https://github.com/tektoncd/pipeline/blob/master/docs/pipelineruns.md) with values from the App and parameters from the `run-task` command.\n4. The Tekton PipelineRun creates a Kubernetes Pod which launches a container based on the configurations on the App and Task.\n5. Task execution stops (Task exits or is terminated manually), the underlying Pod is either stopped or terminated. Pods of stopped Tasks are preserved and thus Task logs are accessible via the `kf logs APP_NAME --task` command.\n6. If you terminate a Task before it stops, the Tekton PipelineRun is cancelled (see [Cancelling a PipelineRun](https://github.com/tektoncd/pipeline/blob/master/docs/pipelineruns.md#cancelling-a-pipelinerun)), the underlying Pod together with the logs are deleted. The logs of termianted Tasks are delivered to the cluster level logging streams if configured (e.g. Stackdriver, Fluentd).\n7. If the number of Tasks run on an App is greater than 500, the oldest Tasks are automatically deleted.\n\nTasks Retention Policy\n----------------------\n\nTasks are created as custom resources in the Kubernetes cluster, therefore, it is important not to exhaust the space of the underlying `etcd` database. By default, Kf only keeps the latest 500 Tasks per each App. Once the number of Tasks reach 500, the oldest Tasks (together with the underlying Pods and logs) will be automatically deleted.\n\nTask Logging and Execution History\n----------------------------------\n\nAny data or messages the Task outputs to STDOUT or STDERR is available by using the `kf logs APP_NAME --task` command. Cluster level logging mechanism (such as Stackdriver, Fluentd) will deliver the Task logs to the configured logging destination.\n\nScheduling Tasks\n----------------\n\nAs described above, Tasks can be run asynchronously by using the `kf run-task APP_NAME` command.\nAlternatively, you can schedule Tasks for execution by first creating a Job using\nthe `kf create-job` command, and then scheduling it with the\n`kf schedule-job JOB_NAME` command. You can schedule that Job to automatically\nrun Tasks on a specified [unix-cron](https://man7.org/linux/man-pages/man5/crontab.5.html) schedule.\n\n### How Tasks are scheduled\n\nCreate and schedule a Job to run the Task. A Job describes the Task to execute\nand automatically manages Task creation.\n\nTasks are created on the schedule even if previous executions of the Task are still running.\nIf any executions are missed for any reason, only the most recently missed execution\nare executed when the system recovers.\n\nDeleting a Job deletes all associated Tasks. If any associated Tasks were still\nin progress, they are forcefully deleted without running to completion.\n\nTasks created by a scheduled Job are still subject to the\n[Task retention policy](#tasks_retention_policy).\n\n### Differences from PCF Scheduler\n\nPCF Scheduler allows multiple schedules for a single Job while Kf\nonly supports a single schedule per Job. You can replicate the PCF Scheduler\nbehavior by creating multiple Jobs, one for each schedule."]]