diff --git a/content/en/blog/_posts/2024-09-17-sig-scheduling-spotlight.md b/content/en/blog/_posts/2024-09-17-sig-scheduling-spotlight.md index c06a6929747bc..dfe75e0f7998f 100644 --- a/content/en/blog/_posts/2024-09-17-sig-scheduling-spotlight.md +++ b/content/en/blog/_posts/2024-09-17-sig-scheduling-spotlight.md @@ -19,7 +19,7 @@ Kubernetes?** **Kensei**: Hi, thanks for the opportunity! I’m Kensei Nakada ([@sanposhiho](https://github.com/sanposhiho/)), a software engineer at [Tetrate.io](https://tetrate.io/). I have been contributing to Kubernetes in my free time for more -than 3 years, and now I’m an approver of SIG-Scheduling in Kubernetes. Also, I’m a founder/owner of +than 3 years, and now I’m an approver of SIG Scheduling in Kubernetes. Also, I’m a founder/owner of two SIG subprojects, [kube-scheduler-simulator](https://github.com/kubernetes-sigs/kube-scheduler-simulator) and [kube-scheduler-wasm-extension](https://github.com/kubernetes-sigs/kube-scheduler-wasm-extension). @@ -32,14 +32,14 @@ brief overview of SIG Scheduling and explain its role within the Kubernetes ecos **KN**: As the name implies, our responsibility is to enhance scheduling within Kubernetes. Specifically, we develop the components that determine which Node is the best place for each Pod. In Kubernetes, our main focus is on maintaining the -[kube-scheduler](https://kubernetes.io/docs/concepts/scheduling-eviction/kube-scheduler/), along +[kube-scheduler](/docs/concepts/scheduling-eviction/kube-scheduler/), along with other scheduling-related components as part of our SIG subprojects. **AP: I see, got it! That makes me curious--what recent innovations or developments has SIG Scheduling introduced to Kubernetes scheduling?** -**KN**: From a feature perspective, there have been [several -enhancements](https://kubernetes.io/blog/2023/04/17/fine-grained-pod-topology-spread-features-beta/) +**KN**: From a feature perspective, there have been +[several enhancements](/blog/2023/04/17/fine-grained-pod-topology-spread-features-beta/) to `PodTopologySpread` recently. `PodTopologySpread` is a relatively new feature in the scheduler, and we are still in the process of gathering feedback and making improvements. @@ -53,59 +53,58 @@ reducing the likelihood of wasting scheduling cycles. **A: That sounds interesting! Are there any other interesting topics or projects you are currently working on within SIG Scheduling?** -**KN**: I’m leading the development of `QueueingHint` which I just shared. Given that it’s a big new +**KN**: I’m leading the development of `QueueingHint` which I just shared. Given that it’s a big new challenge for us, we’ve been facing many unexpected challenges, especially around the scalability, and we’re trying to solve each of them to eventually enable it by default. And also, I believe -[kube-scheduler-wasm-extention](https://github.com/kubernetes-sigs/kube-scheduler-wasm-extension) -(SIG sub project) that I started last year would be interesting to many people. Kubernetes has +[kube-scheduler-wasm-extension](https://github.com/kubernetes-sigs/kube-scheduler-wasm-extension) +(a SIG subproject) that I started last year would be interesting to many people. Kubernetes has various extensions from many components. Traditionally, extensions are provided via webhooks ([extender](https://github.com/kubernetes/design-proposals-archive/blob/main/scheduling/scheduler_extender.md) -in the scheduler) or Go SDK ([Scheduling -Framework](https://kubernetes.io/docs/concepts/scheduling-eviction/scheduling-framework/) in the -scheduler). However, these come with drawbacks - performance issues with webhooks and the need to +in the scheduler) or Go SDK ([Scheduling Framework](/docs/concepts/scheduling-eviction/scheduling-framework/) +in the scheduler). However, these come with drawbacks - performance issues with webhooks and the need to rebuild and replace schedulers with Go SDK, posing difficulties for those seeking to extend the -scheduler but lacking familiarity with it. The project is trying to introduce a new solution to +scheduler but lacking familiarity with it. The project is trying to introduce a new solution to this general challenge - a [WebAssembly](https://webassembly.org/) based extension. Wasm allows users to build plugins easily, without worrying about recompiling or replacing their scheduler, and sidestepping performance concerns. -Through this project, sig-scheduling has been learning valuable insights about WebAssembly's +Through this project, SIG Scheduling has been learning valuable insights about WebAssembly's interaction with large Kubernetes objects. And I believe the experience that we’re gaining should be -useful broadly within the community, beyond sig-scheduling. +useful broadly within the community, beyond SIG Scheduling. -**A: Definitely! Now, there are currently 8 subprojects inside SIG Scheduling. Would you like to +**A: Definitely! Now, there are 8 subprojects inside SIG Scheduling. Would you like to talk about them? Are there some interesting contributions by those teams you want to highlight?** -**KN**: Let me pick up three sub projects; Kueue, KWOK and descheduler. +**KN**: Let me pick up three subprojects: Kueue, KWOK and descheduler. -[Kueue](https://github.com/kubernetes-sigs/kueue): +[Kueue](https://github.com/kubernetes-sigs/kueue) : Recently, many people have been trying to manage batch workloads with Kubernetes, and in 2022, -Kubernetes community founded -[WG-Batch](https://github.com/kubernetes/community/blob/master/wg-batch/README.md) for better -support for such batch workloads in Kubernetes. [Kueue](https://github.com/kubernetes-sigs/kueue) -is a project that takes a crucial role for it. It’s a job queueing controller, deciding when a job -should wait, when a job should be admitted to start, and when a job should be preempted. Kueue aims -to be installed on a vanilla Kubernetes cluster while cooperating with existing matured controllers -(scheduler, cluster-autoscaler, kube-controller-manager, etc). - -[KWOK](https://github.com/kubernetes-sigs/kwok): + Kubernetes community founded + [WG-Batch](https://github.com/kubernetes/community/blob/master/wg-batch/README.md) for better + support for such batch workloads in Kubernetes. [Kueue](https://github.com/kubernetes-sigs/kueue) + is a project that takes a crucial role for it. It’s a job queueing controller, deciding when a job + should wait, when a job should be admitted to start, and when a job should be preempted. Kueue aims + to be installed on a vanilla Kubernetes cluster while cooperating with existing matured controllers + (scheduler, cluster-autoscaler, kube-controller-manager, etc). + +[KWOK](https://github.com/kubernetes-sigs/kwok) : KWOK is a component in which you can create a cluster of thousands of Nodes in seconds. It’s mostly useful for simulation/testing as a lightweight cluster, and actually another SIG sub project [kube-scheduler-simulator](https://github.com/kubernetes-sigs/kube-scheduler-simulator) uses KWOK background. -[descheduler](https://github.com/kubernetes-sigs/descheduler): -: Descheduler is a component recreating pods that are running on undesired Nodes. In Kubernetes, -scheduling constraints (`PodAffinity`, `NodeAffinity`, `PodTopologySpread`, etc) are honored only at -Pod schedule, but it’s not guaranteed that the contrtaints are kept being satisfied afterwards. -Descheduler evicts Pods violating their scheduling constraints (or other undesired conditions) so -that they’re recreated and rescheduled. +[descheduler](https://github.com/kubernetes-sigs/descheduler) +: Descheduler is a component recreating pods that are running on undesired Nodes. In Kubernetes, + scheduling constraints (`PodAffinity`, `NodeAffinity`, `PodTopologySpread`, etc) are honored only at + Pod schedule, but it’s not guaranteed that the contrtaints are kept being satisfied afterwards. + Descheduler evicts Pods violating their scheduling constraints (or other undesired conditions) so + that they’re recreated and rescheduled. -[Descheduling Framework](https://github.com/kubernetes-sigs/descheduler/blob/master/keps/753-descheduling-framework/README.md). -: One very interesting on-going project, similar to [Scheduling - Framework](https://kubernetes.io/docs/concepts/scheduling-eviction/scheduling-framework/) in the +[Descheduling Framework](https://github.com/kubernetes-sigs/descheduler/blob/master/keps/753-descheduling-framework/README.md) +: One very interesting on-going project, similar to + [Scheduling Framework](/docs/concepts/scheduling-eviction/scheduling-framework/) in the scheduler, aiming to make descheduling logic extensible and allow maintainers to focus on building a core engine of descheduler. @@ -125,27 +124,26 @@ improving our components over the years. **AP: Kubernetes is a community-driven project. Any recommendations for new contributors or beginners looking to get involved and contribute to SIG scheduling? Where should they start?** -**KN**: Let me start with a general recommendation for contributing to any SIG: a common approach is -to look for +**KN**: Let me start with a general recommendation for contributing to any SIG: a common approach is to look for [good-first-issue](https://github.com/kubernetes/kubernetes/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22). However, you'll soon realize that many people worldwide are trying to contribute to the Kubernetes repository. I suggest starting by examining the implementation of a component that interests you. If you have any questions about it, ask in the corresponding Slack channel (e.g., #sig-scheduling for the -scheduler, #sig-node for kubelet, etc). Once you have a rough understanding of the implementation, +scheduler, #sig-node for kubelet, etc). Once you have a rough understanding of the implementation, look at issues within the SIG (e.g., [sig-scheduling](https://github.com/kubernetes/kubernetes/issues?q=is%3Aopen+is%3Aissue+label%3Asig%2Fscheduling)), -where you'll find more unassigned issues compared to good-first-issue ones. You may also want to +where you'll find more unassigned issues compared to good-first-issue ones. You may also want to filter issues with the [kind/cleanup](https://github.com/kubernetes/kubernetes/issues?q=is%3Aopen+is%3Aissue++label%3Akind%2Fcleanup+) label, which often indicates lower-priority tasks and can be starting points. -Specifically for SIG Scheduling, you should first understand the [Scheduling -Framework](https://kubernetes.io/docs/concepts/scheduling-eviction/scheduling-framework/), which is -the fundamental architecture of kube-scheduler. Most of the implementation is found in -[pkg/scheduler](https://github.com/kubernetes/kubernetes/tree/master/pkg/scheduler). I suggest -starting with +Specifically for SIG Scheduling, you should first understand the +[Scheduling Framework](/docs/concepts/scheduling-eviction/scheduling-framework/), which is +the fundamental architecture of kube-scheduler. Most of the implementation is found in +[pkg/scheduler](https://github.com/kubernetes/kubernetes/tree/master/pkg/scheduler). +I suggest starting with [ScheduleOne](https://github.com/kubernetes/kubernetes/blob/0590bb1ac495ae8af2a573f879408e48800da2c5/pkg/scheduler/schedule_one.go#L66) function and then exploring deeper from there. @@ -154,15 +152,14 @@ sub-projects. These typically have fewer maintainers and offer more opportunitie significant impact. Despite being called "sub" projects, many have a large number of users and a considerable impact on the community. -And last but not least, remember contributing to the community isn’t just about code. While I +And last but not least, remember contributing to the community isn’t just about code. While I talked a lot about the implementation contribution, there are many ways to contribute, and each one is valuable. One comment to an issue, one feedback to an existing feature, one review comment in PR, one clarification on the documentation; every small contribution helps drive the Kubernetes ecosystem forward. **AP: Those are some pretty useful tips! And if I may ask, how do you assist new contributors in -getting started, and what skills are contributors likely to learn by participating in SIG -Scheduling?** +getting started, and what skills are contributors likely to learn by participating in SIG Scheduling?** **KN**: Our maintainers are available to answer your questions in the #sig-scheduling Slack channel. By participating, you'll gain a deeper understanding of Kubernetes scheduling and have the @@ -178,9 +175,8 @@ pain points?** **KN**: Scheduling in Kubernetes can be quite challenging because of the diverse needs of different organizations with different business requirements. Supporting all possible use cases in kube-scheduler is impossible. Therefore, extensibility is a key focus for us. A few years ago, we -rearchitected kube-scheduler with [Scheduling -Framework](https://kubernetes.io/docs/concepts/scheduling-eviction/scheduling-framework/), which -offers flexible extensibility for users to implement various scheduling needs through plugins. This +rearchitected kube-scheduler with [Scheduling Framework](/docs/concepts/scheduling-eviction/scheduling-framework/), +which offers flexible extensibility for users to implement various scheduling needs through plugins. This allows maintainers to focus on the core scheduling features and the framework runtime. Another major issue is maintaining sufficient scheduling throughput. Typically, a Kubernetes cluster @@ -190,7 +186,7 @@ and, consequently, the cluster's scalability. Although we have an internal perfo unfortunately, we sometimes overlook performance degradation in less common scenarios. It’s difficult as even small changes, which look irrelevant to performance, can lead to degradation. -**AP: What are some upcoming goals or initiatives for SIG Scheduling? How do you envision the SIG evolving in the future?** +**AP: What are some upcoming goals or initiatives for SIG Scheduling? How do you envision the SIG evolving in the future?** **KN**: Our primary goal is always to build and maintain _extensible_ and _stable_ scheduling runtime, and I bet this goal will remain unchanged forever. @@ -198,7 +194,7 @@ runtime, and I bet this goal will remain unchanged forever. As already mentioned, extensibility is key to solving the challenge of the diverse needs of scheduling. Rather than trying to support every different use case directly in kube-scheduler, we will continue to focus on enhancing extensibility so that it can accommodate various use -cases. [kube-scheduler-wasm-extention](https://github.com/kubernetes-sigs/kube-scheduler-wasm-extension) +cases. [kube-scheduler-wasm-extension](https://github.com/kubernetes-sigs/kube-scheduler-wasm-extension) that I mentioned is also part of this initiative. Regarding stability, introducing new optimizations like QueueHint is one of our @@ -217,7 +213,7 @@ about SIG Scheduling?** **KN**: Scheduling is one of the most complicated areas in Kubernetes, and you may find it difficult at first. But, as I shared earlier, you can find many opportunities for contributions, and many maintainers are willing to help you understand things. We know your unique perspective and skills -are what makes our open source so powerful :) +are what makes our open source so powerful 😊 Feel free to reach out to us in Slack ([#sig-scheduling](https://kubernetes.slack.com/archives/C09TP78DV)) or