You can execute short-lived workflows by running them as Tasks in Kf. Tasks are run under Apps, meaning each Task must have an associated App. Each Task execution uses the build arttifacts from the parent App. Because Tasks are short-lived, the App will not be deployed as a long-running application, and no routes should be created for the App or the Task.
Push an App for running Tasks
Navigate to the directory of the App manifest or source code and create an App for running Tasks with the kf push APP_NAME --task command. The --task flag indicates that the App is meant to be used for running Tasks, and thus no routes will be created on the App and it will not be deployed as a long-running application.
$ kf push helloworld --task
Confirm that no App instances or routes were created by listing the App.
$ kf apps
Listing Apps in Space: test-space
Name Instances Memory Disk CPU URLs
helloworld stopped 1Gi 1Gi 100m <nil>
Run Task on App
When you run a Task on the App, you can optionally specify a start command using the --command flag. If no start command is specified, it uses the start command specified on the App. If the App doesn't have a start command specified, it looks up the CMD configuration of the container image. A start command must exists in order to run Task successfully.
$ kf run-task helloworld --command "printenv"
Task helloworld-gd8dv is submitted successfully for execution.
The Task name is automatically generated in the Kubernetes API Server. It is prefixed with the App name and surfixed with an arbitrary string. The Task name is an unique identifier for Tasks within the same cluster.
Specify Task resource limits
Resource limits (such as CPU cores/Memory limit/Disk quota) can be specified in the App (during kf push) or during the kf run-task command. The limits specified in the kf run-task command take prededence over the limits specified on the App.
To specify resource limits in an App, you can use the --cpu-cores, --memory-limit and --disk-quota flags in the kf push command.
$ kf push helloworld --command "printenv" --cpu-cores=0.5 --memory-limit=2G --disk-quota=5G --task
To override these limits in the App, you can use the --cpu-cores, --memory-limit and --disk-quota flags in the kf run-task command.
$ kf run-task helloworld --command "printenv" --cpu-cores=0.5 --memory-limit=2G --disk-quota=5G
Specify a custom display name for a Task
You can optionally use the --name flag to specify a custom display name for a Task for easier identification/grouping.
$ kf run-task helloworld --command "printenv" --name foo
Task helloworld-6swct is submitted successfully for execution.
$ kf tasks helloworld
Listing Tasks in Space: test space
Name ID DisplayName Age Duration Succeeded Reason
helloworld-6swct 3 foo 1m 21s True <nil>
Managing Tasks
View all Tasks of an App with the kf tasks APP_NAME command.
$ kf tasks helloworld
Listing Tasks in Space: test space
Name ID DisplayName Age Duration Succeeded Reason
helloworld-gd8dv 1 helloworld-gd8dv 1m 21s True <nil>
Cancel a Task
Cancel an active Task using the kf terminate-task command.
Cancel a Task by Task name.
$ kf terminate-task helloworld-6w6mz
Task "helloworld-6w6mz" is successfully submitted for termination
Or cancel a Task by APP_NAME + Task ID.
$ kf terminate-task helloworld 2
Task "helloworld-6w6mz" is successfully submitted for termination
- Note: You can only cancel Tasks that are pending/running, completed Tasks are not cancellable.
Cancelled Tasks have PipelineRunCancelled status.
$ kf tasks helloworld
Listing Tasks in Space: test space
Name ID DisplayName Age Duration Succeeded Reason
helloworld-gd8dv 1 helloworld-gd8dv 1m 21s True <nil>
helloworld-6w6mz 2 helloworld-6w6mz 38s 11s False PipelineRunCancelled
View Task logs
View logs of a Task using the kf logs APP_NAME --task command.
$ kf logs helloworld --task