Wait Custom Task for Tekton

This repo provides an experimental Tekton Custom Task that, when run, simply waits a given amount of time before succeeding, specified by an input parameter named duration.

Motivation

Some users might want their Pipeline to wait some amount of time between two tasks, for example, to deploy to one cluster then wait an hour before deploying to other clusters.

This is possible without this Custom Task using a Task that sleeps (e.g., script: sleep 600), but this results in Pods running on the cluster that are just sleeping. This wastes cluster resources, and if nodes on the cluster go down then those sleeps will fail, leading to flaky deployments.

Instead, this Custom Task centralizes all wait operations in the Custom Task controller, which is more efficient and more fault tolerant.

This also acts as a simple Custom Task that can be modified to perform other more complex actions.

Install

Install and configure ko.

ko apply -f controller.yaml

This will build and install the controller on your cluster, in the namespace wait-task.

Example

Create an example Run that waits for 10 seconds:

$ kubectl create -f example-run.yaml 
run.tekton.dev/wait-run-5pnzz created
$ kubectl get runs -w
NAME             SUCCEEDED   REASON    STARTTIME   COMPLETIONTIME
wait-run-5pnzz   Unknown     Waiting   2s          
wait-run-5pnzz   True        DurationElapsed   10s         0s

Run an example Pipeline that includes a Wait task:

NB: In order for this to work, you will need to update the "enable-custom-tasks" feature-flag. See Using Custom Tasks.

$ tkn pipeline start -f example-pipeline.yaml --showlog
PipelineRun started: custom-task-pipeline-run-xbqhg
Waiting for logs to be available...
[before : unnamed-0] + echo before wait
[before : unnamed-0] before wait

[after : unnamed-0] after wait
[after : unnamed-0] + echo after wait

Uninstall

$ kubectl delete namespace wait-task
namespace "wait-task" deleted

This will stop the controller and delete its namespace.