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KEP-74: support argo workflow #2976

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@KunWuLuan KunWuLuan commented Sep 4, 2024

What type of PR is this?

/kind documentation
/kind feature

What this PR does / why we need it:

#74

Which issue(s) this PR fixes:

Special notes for your reviewer:

Does this PR introduce a user-facing change?

NONE

@k8s-ci-robot k8s-ci-robot added do-not-merge/work-in-progress Indicates that a PR should not merge because it is a work in progress. kind/documentation Categorizes issue or PR as related to documentation. do-not-merge/release-note-label-needed Indicates that a PR should not merge because it's missing one of the release note labels. labels Sep 4, 2024
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[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: KunWuLuan
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@k8s-ci-robot k8s-ci-robot added cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. needs-ok-to-test Indicates a PR that requires an org member to verify it is safe to test. labels Sep 4, 2024
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Hi @KunWuLuan. Thanks for your PR.

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@k8s-ci-robot k8s-ci-robot added the size/L Denotes a PR that changes 100-499 lines, ignoring generated files. label Sep 4, 2024
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kannon92 commented Sep 5, 2024

/ok-to-test

@k8s-ci-robot k8s-ci-robot added ok-to-test Indicates a non-member PR verified by an org member that is safe to test. and removed needs-ok-to-test Indicates a PR that requires an org member to verify it is safe to test. labels Sep 5, 2024
@KunWuLuan KunWuLuan changed the title WIP: kep-74: support argo workflow KEP-74: support argo workflow Sep 10, 2024
@k8s-ci-robot k8s-ci-robot removed the do-not-merge/work-in-progress Indicates that a PR should not merge because it is a work in progress. label Sep 10, 2024
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It seems that some sections are still empty. So, when you fill all sections, we will review this KEP.

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@tenzen-y Hi, I filled in the empty sections. And some implement details will be added after we discuss and choose the road.

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@tenzen-y Hi, I filled in the empty sections. And some implement details will be added after we discuss and choose the road.

Thanks for the updates.
@KunWuLuan Could you resolve CI errors with "make toc-update"?

@k8s-ci-robot k8s-ci-robot added do-not-merge/work-in-progress Indicates that a PR should not merge because it is a work in progress. size/XXL Denotes a PR that changes 1000+ lines, ignoring generated files. and removed size/L Denotes a PR that changes 100-499 lines, ignoring generated files. labels Sep 24, 2024
@KunWuLuan KunWuLuan changed the title [WIP] KEP-74: support argo workflow KEP-74: support argo workflow Sep 24, 2024
@k8s-ci-robot k8s-ci-robot removed the do-not-merge/work-in-progress Indicates that a PR should not merge because it is a work in progress. label Sep 24, 2024
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Thank you for driving this @KunWuLuan!
I left my initial questions.

keps/74-support-argo-workflow/README.md Outdated Show resolved Hide resolved
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// stage should be implemented as GenericJob
stages := wf.GetActiveStages()
for _, stage := range stages {
// 1. make sure there is only a single existing instance of the workload.

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What do you mean by single existing instance of workload here ?

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For a specific stage which may refer to a stageGroup in workflow's status in workflow, we create a kueue.workload to track the resource requests.


#### How to suspend by stages

In my daily work, I primarily encounter workflow managers in the form of Argo and Tekton. Consequently, this section will focus on these two. Other workflow management systems can draw upon the discussions in this section for implementation guidance.

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Do we have any significant differences between Argo/Tekton and Airflow when we execute workflows in Kubernetes?
cc @shravan-achar @akshaychitneni @bigsur0

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It seems suspend action in Tekton is not supported.

spec:
entrypoint: loop-example-depth-1
templates:
- name: kueue-suspend

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Does it mean that you are going to mutate the existing Workflow with kueue-suspend step ?
Why not just mutate the suspend: true parameter to every step ?

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Does it mean that you are going to mutate the existing Workflow with kueue-suspend step ?

Yes

Why not just mutate the suspend: true parameter to every step ?

Change suspend to false will start all suspend steps. Adding suspend template before every leaf template allow us to control the start of specific steps. For example, for the DAG like this:

A
|  \
B  C

I think step B and step C should wait for different workload admissions.

args: ["3m"]
```

Option 3. Kueue Webhook Enhancement: A new webhook is added within Kueue to intercept pod creations in the cluster.

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How the Argo Workflow controller will reconcile steps if Pods will be in SchedulingGated status ?

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AFAIK, SchedulingGated status is almost same with pending status, so it should not have any effect to Argo Workflow controller. Maybe @terrytangyuan can give us some more information.

}


func (r *workflowReconciler)ReconcileGenericWorkflow(ctx context.Context, req ctrl.Request, wf GenericWorkflow) {
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@tenzen-y tenzen-y Sep 25, 2024

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Why do we need this workflow dedicated Reconciler?
We want to keep using the ReconcileGenericJob. The CompsableJob is a good example of how to perform the special typed Job in the generic Job reconciler.

Could you propose an approach to extend the ReconcileGenericJob by WorkflowJob interface?

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I will try to consider about this.

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Updated the design.

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@terrytangyuan Hi, do you have any comments on these options? I think we need the feedback of workflow managers to determine what Kueue can do in its framework.

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@terrytangyuan Hi, do you have any comments on these options? I think we need the feedback of workflow managers to determine what Kueue can do in its framework.

Thanks for the ping. I'll take a look when I get a chance. Will you be willing to drive and implement the changes needed on Argo Workflows side too?

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@terrytangyuan Oh, yes. I am willing to do this.

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Sorry folks. With the k/k enhancements freeze, I had little time to read this. I'll try to make some time soon.

cc @mimowo


In this section, we will discuss the advantages and disadvantages of queuing Workflows, Stages, and Tasks individually. Additionally, we will explore how each of these can be implemented within Kueue.

### What are the Stages for Argo Workflows?
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It's not clear to me what a stage is.
Is it an Argo concept that I'm missing? If so, can you add a link to its definition in the Argo documentation?
Otherwise, can you please elaborate a bit more?

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Stage is not a concept in Argo. I try to use a new word to represent the process that will create a set of pods in workflow. In Argo this may be a TaskGroup, or a StepGroup.
You can see the section 'What are the Stages for Argo Workflows'. If there are still some question the concept of stage, I will try to explain more in the section.

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mimowo commented Oct 14, 2024

@KunWuLuan thank you for driving the KEP. I will try to get to it this week. cc @mwielgus

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@KunWuLuan: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

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pull-kueue-verify-main fc0837d link true /test pull-kueue-verify-main

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mimowo commented Oct 17, 2024

Sorry folks, this is an important KEP, but I will not be able to review it before 0.9 release is concluded.

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Hello friends, anyone have any comment?

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Hello friends, anyone have any comment?

We assume to aim for this feature after the next release (v0.11) since the v0.10 deadline will come soon, within 2 weeks.

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