I really struggle to see the point of k8s for large computational workloads. It adds a lot of complexity, and I don’t see what benefit it brings.

If you really want to run containerised workloads as batch jobs on AWS, for example, then it’s a great deal simpler to do so using AWS Batch and ECS rather than doing all that stuff with Kubernetes.

Creating a Batch queue and job definition in CDK can be done in a couple of dozen lines of code. See the example I wrote a year or so ago, recently updated now that AWS Batch has fully supported L2 constructs in CDK: https://github.com/tcutts/cdk-batch-python/tree/main which has a few more bells and whistles, like triggering batch job submissions as files arrive in an S3 bucket, and closing the queue to jobs automatically if a budget threshold is exceeded, but it’s still only about 200 lines of code.

I really don’t understand what k8s would add to that sort of architecture. In fact, when AWS added support for EKS to AWS Batch, I asked the internal team what the point of that was, and it was basically just “some customers insisted on it”. No-one could actually articulate for me what tangible benefit there was to it.

Tim

-- Tim Cutts Scientific Computing Platform Lead AstraZeneca

Find out more about R&D IT Data, Analytics & AI and how we can support you by visiting our Service Cataloguehttps://azcollaboration.sharepoint.com/sites/CMU993 |

From: Sylvain MARET via slurm-users slurm-users@lists.schedmd.com Date: Wednesday, 13 March 2024 at 10:29 To: Nicolas Greneche nicolas.greneche@univ-paris13.fr, slurm-users@lists.schedmd.com slurm-users@lists.schedmd.com Subject: [slurm-users] Re: SLURM in K8s, any advice? Hello,

I haven't played with slurm in k8s but I did attend this talk : https://fosdem.org/2024/schedule/event/fosdem-2024-2590-kubernetes-and-hpc-b...https://fosdem.org/2024/schedule/event/fosdem-2024-2590-kubernetes-and-hpc-bare-metal-bros

Which shows at least someone was able to do so and maybe it'll be worth to talk to her about it. I wanted to ask her for the code to reproduce her experiment but I don't have the time yet to do so.

Regards, Sylvain Maret

On 13/03/2024 11:04, Nicolas Greneche via slurm-users wrote:

CAUTION : External Sender. Please do not click on links or open attachments from senders you do not trust.

Hi Alan,

Your topic is indeed my PhD thesis (defended late november). It consists in building autoscaling HPC infrastructure in the cloud (in a compute node provisioning point of view). In this work I show that kubernetes default controllers are not well designed for autoscaling containerized HPC clusters [1] and I wrote a super basic K8s controller for OAR [2] (another scheduler developped at INRIA). This controller deserves a rewrite, it's only a proof of concept ^^.

My guess is that you have nesting issues with cgroup/v2 inside your containerized compute node (those that runs slurmd) ? If it's the case may be you can use katacontainers [3] instead of CRI-O as a container engine [4] (I made it in 2021). The main asset of katacontainers is that it can use KVM.

The consequence is that your CPU is a "real" vcpus and not a quota enforced by cgroups. I noticed that with kata, my slurmd containers had a cpuinfos / nproc that reflected the limits enforced in my K8s manifest. I didn't went deep with kata because I focused on "controller" aspect of things. But using KVM may hide the nesting of cgroups to slurmd ?

I hope this help !

Kind regards,

[1] A methodology to scale containerized HPC infrastructures in the Cloud Nicolas Greneche, Christophe Cérin and PTarek Menouer at Euro-par 2022

[2] Autoscaling of Containerized HPC Clusters in the Cloud Nicolas Greneche, Christophe Cerin at SuperCompCloud: 6th Workshop on Interoperability of Supercomputing and Cloud Technologies (Held in conjunction with SC'22)

[3] https://katacontainers.iohttps://katacontainers.io

[4] https://github.com/kata-containers/documentation/blob/master/how-to/run-kata...https://github.com/kata-containers/documentation/blob/master/how-to/run-kata-with-k8s.md

Le 13/03/2024 à 09:06, LEAVY Alan via slurm-users a écrit :

...

I’m a little late to this party but would love to establish contact with others using slurm in Kubernetes.

I recently joined a research institute in Vienna (IIASA) and I’m getting to grips with slurm and Kubernetes (my previous role was data engineering / fintech). My current setup sounds like what Urban described in this thread, back in Nov 22. It has some rough edges though.

Right now, I’m trying to upgrade to slurm-23.11.4 in Ubuntu 23.10 containers. I’m having trouble with the cgroup/v2 plugin.

Are you still using slurm on K8s Urban? How did your installation work out Hans? Would either of you be willing to share your experiences?

Regards,

 Alan.

-- Nicolas Greneche USPN / DSI Support à la recherche / RSSI Suppléant https://www-magi.univ-paris13.frhttps://www-magi.univ-paris13.fr

-- slurm-users mailing list -- slurm-users@lists.schedmd.com To unsubscribe send an email to slurm-users-leave@lists.schedmd.com

-- slurm-users mailing list -- slurm-users@lists.schedmd.com To unsubscribe send an email to slurm-users-leave@lists.schedmd.com ________________________________

AstraZeneca UK Limited is a company incorporated in England and Wales with registered number:03674842 and its registered office at 1 Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0AA.

This e-mail and its attachments are intended for the above named recipient only and may contain confidential and privileged information. If they have come to you in error, you must not copy or show them to anyone; instead, please reply to this e-mail, highlighting the error to the sender and then immediately delete the message. For information about how AstraZeneca UK Limited and its affiliates may process information, personal data and monitor communications, please see our privacy notice at www.astrazeneca.comhttps://www.astrazeneca.com