Running tasks in your apps

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A task is an app or script, the code of which is included as part of a deployed app, but runs independently in its own container. This topic describes how to run tasks in Cloud Foundry.

Tasks in Cloud Foundry

In contrast to a long-running process (LRP), tasks run for a finite amount of time, then stop. Tasks run in their own containers and are designed to use minimal resources. After a task runs, Cloud Foundry destroys the container running the task.

As a single use object, a task can be checked for its state and for a success or failure message.

Use cases for tasks

Tasks are used to perform one-off jobs, which include:

• Migrating a database
• Sending an email
• Running a batch job
• Running a data processing script
• Processing images
• Optimizing a search index
• Uploading data
• Backing-up data
• Downloading content

How tasks are run

Tasks are always run asynchronously, meaning that they run independently from the parent app or other tasks that run on the same app.

The life cycle of a task is as follows:

1. A user initiates a task in Cloud Foundry using one of the following mechanisms:

   • The cf run-task APP-NAME "TASK" command. For more information, see Running tasks in your apps.
   • A Cloud Controller v3 API call. For more information, see the Cloud Foundry API documentation.
   • The Cloud Foundry Java Client. For more information, see Cloud Foundry Java Client Library and the Cloud Foundry Java Client repository on GitHub.

2. Cloud Foundry creates a container specifically for the task.

3. Cloud Foundry runs the task on the container using the value passed to the cf run-task command.

4. Cloud Foundry destroys the container.

The container also inherits environment variables, service bindings, and security groups bound to the app.

You cannot SSH into the container running a task.

In the BOSH Cloud Controller Worker job, the cc.default_app_memory and cc.default_app_disk_in_mb properties specify the default memory and disk allocations for tasks.

The cc.default_app_log_rate_limit_in_bytes_per_second property specifies the default log rate limit. For more information about BOSH Cloud Controller Worker jobs, see BOSH documentation.

To run tasks with the cf CLI, you must install cf CLI v8. To download, install, and uninstall the cf CLI, see Installing the Cloud Foundry Command Line Interface.

Run a task on an app with cf CLI

To run a task on an app with cf CLI v8:

1. Configure your v3 API manifest with a task as a process type. For more information, see the Cloud Foundry API documentation.

2. In a terminal, push your app by running:

   cf push APP-NAME --task
   

   Where APP-NAME is the name of your app.

3. Run your task on the deployed app by running:

   cf run-task APP-NAME --name TASK-NAME
   

   Where:

   • APP-NAME is the name of your app.
   • TASK-NAME is the name you want to give the task.

   cf run-task allows you to include the --process and --command flags. Including the --command flag overrides the manifest property.

   The following example command runs a task on the example-app app:

   cf run-task example-app --name example-task
   

   When the task runs successfully, you see terminal output similar to the following example:

   Creating task for app example-app in org example-org / space development as [email protected]...
   OK
   Task 1 has been submitted successfully for execution.
   

4. To display the recent logs of the app and all its tasks, run:

   cf logs APP-NAME --recent
   

   Where APP-NAME is the name of your app.

Get a task for an app

To get a task for a given app:

1. In a terminal window, run:

   cf task APP-NAME TASK-ID
   

   Where APP-NAME is the name of your app and TASK-ID is the ID of the task you want to get.

   The command returns output similar to the following example:

   Getting task 4 for app static in org org-1 / space space-1 as admin...
   
   id:               4
   name:             125c884d
   state:            FAILED
   start time:       2024-11-22T17:41:19Z
   command:          custom_command
   memory in mb:     256
   disk in mb:       1024
   log rate limit:   -1
   failure reason:   APP/TASK/125c884d: Exited with status 127
   

Tasks can be in the states shown in the following table:

List tasks running on an app

To list the tasks for a given app:

1. In a terminal window, run:

   cf tasks APP-NAME
   

   Where APP-NAME is the name of your app. The command returns output similar to the following example:

   Getting tasks for app example-app in org example-org / space development as [email protected]...
   OK
   
   
   id   name       state       start time                      command
   2    339044ef   FAILED      Wed, 23 Nov 2016 21:52:52 UTC   echo foo; sleep 100; echo bar
   1    8d0618cf   SUCCEEDED   Wed, 23 Nov 2016 21:37:28 UTC   bin/rails db:migrate
   

Tasks can be in these states:

Cancel a task

After you run a task, you might be able to cancel it before it finishes.

To cancel a running task:

1. In a terminal window, run:

   cf terminate-task APP-NAME TASK-ID
   

   Where:

   • APP-NAME is the name of your app.
   • TASK-NAME is the name you want to give the task.

   The previous command returns output similar to the following example:

   Terminating task 2 of app example-app in org example-org / space development as [email protected]...
   OK