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SE Radio 649: Lukas Gentele on Kubernetes vClusters
Lukas Gentele, CEO of Loft Labs, joins host Robert Blumen for a discussion of kubernetes vclusters (virtual clusters). A vcluster is a kubernetes cluster that runs kubernetes application on a host kubernetes cluster. The conversation covers: vcluster basics; sharing models; what is owned by the vcluster and what is shared with the host; attached nodes versus shared nodes; the primary use case: multi-tenancy vcluster per tenant; alternatives - namespace per tenant, full cluster per tenant; trade-offs - isolation; less resource use; spin up time; scalability; how many clusters and how many vclusters should an org have? Deployment models for vclusters - helm chart with standard resources; vcluster operator; persistent storage models for vclusters; vcluster snapshotting, recovery, and migration. how many vclusters can run on a cluster? ingress, TLS and DNS. Brought to you by IEEE Computer Society and IEEE Software magazine.
Lukas Gentele, CEO of Loft Labs, joins host Robert Blumen for a discussion of kubernetes vclusters (virtual clusters). A vcluster is a kubernetes cluster that runs kubernetes application on a host kubernetes cluster. The conversation covers: vcluster basics; sharing models; what is owned by the vcluster and what is shared with the host; attached nodes versus shared nodes; the primary use case: multi-tenancy vcluster per tenant; alternatives – namespace per tenant, full cluster per tenant; trade-offs – isolation; less resource use; spin up time; scalability; how many clusters and how many vclusters should an org have? Deployment models for vclusters – helm chart with standard resources; vcluster operator; persistent storage models for vclusters; vcluster snapshotting, recovery, and migration. how many vclusters can run on a cluster? ingress, TLS and DNS. Brought to you by IEEE Computer Society and IEEE Software magazine.
Show Notes
- Loft Labs blog: Meet the Loft Labs Team at KubeCon LA
- Lukas Gentele talk at KubeCon 2021: Beyond Namespaces Virtual Clusters are the Future of Multi Tenancy
- Article: Virtual Kubernetes Clusters
- A quick look at Virtual Kubernetes Clusters by Utkarsh Shigihalli
Related Episodes
Transcript
Transcript brought to you by IEEE Software magazine and IEEE Computer Society. This transcript was automatically generated. To suggest improvements in the text, please contact [email protected] and include the episode number.
Robert Blumen 00:00:19 For Software Engineering Radio, this is Robert Blumen. I have with me today Lukas Gentele, the CEO of Loft Labs. Lukas is a maintainer of the open-source projects, vCluster.com, DevPod.sh, and DevSpace.sh. And he is a speaker at KubeCon and other Cloud Computing conferences. Lukas, welcome to Software Engineering Radio.
Lukas Gentele 00:00:45 Great to be here, Robert. Thanks for inviting me on the show.
Robert Blumen 00:00:48 Would you like to tell the listeners anything else about your background that I didn’t cover?
Lukas Gentele 00:00:53 Well, you mentioned all the open-source projects that I’m a startup founder. Yeah, very deeply connected to the Kubernetes ecosystem, to the open-source world. Maybe one thing that you haven’t mentioned yet, I didn’t grow up in the States. I grew up in Germany. Moved here about like six years ago or so, and yeah, very excited to talk a little bit more about specifically all vCluster project today.
Robert Blumen 00:01:16 Yeah, and I will mention that we have an international audience of listeners. The show was founded in Germany, and Germany is one of our top listener countries by percentage. So I’m sure many Germans will be listening to this podcast. Today, Lukas and I will be talking about vClusters. We have quite a lot of content in the archives about Kubernetes clusters that listeners could listen to get up to speed on that, including Episode 590 on How to Set-up a Cluster. Let’s not review that. Let’s dive into Kubernetes vClusters. What is a vCluster, and how does it differ from, what do we call it, a ‘base cluster’ or a ‘normal cluster’? What’s the term you use that’s not a vCluster?
Lukas Gentele 00:02:06 I typically refer to it as a traditional Kubernetes cluster. And then the virtual cluster is something that runs on top of this traditional cluster. We also use it as the term called host cluster. When you have multiple virtual clusters running on the same cluster, that underlying cluster we refer to as the host cluster. The difference between the two ultimately is, Kubernetes cluster is made out of machines. Whether that is bare metal machines or virtual machines, ultimately it’s about how do we schedule containers across a set of machines. And each Kubernetes cluster has these machines attached to these nodes. And some cloud providers allow you to auto scale your nodes to ultimately, add and remove nodes dynamically depending on how many containers you have running. But you can’t have a dynamic allocation of nodes to multiple Kubernetes clusters.
Lukas Gentele 00:03:01 So when you have two Kubernetes clusters and you have one node, you got to put it in either one of these clusters, you can’t share that node across two Kubernetes cluster. A virtual cluster uses the nodes of the underlying cluster. So typically virtual cluster itself doesn’t have any compute nodes. You can obviously attach dedicated compute nodes to it if you wish to do so. But the big benefit of it is, it uses the nodes and the infrastructure of the underlying cluster. So it’s a really great solution for multi-tenancy. If I’m looking at a Kubernetes cluster and I want to share this cluster, that’s really hard to do actually. And that is actually not obvious because when you’re thinking of Kubernetes, there’s obviously role-based access control, there’s users and groups. So you’d think it’s possible to share it. There’s Namespaces and Kubernetes as a unit to separate things a little bit. But again, I usually tell people when you think of a physical server, you also have users and groups and permissions and folders. But it’s still very hard to share a Linux host if you don’t have virtualization. And the same way it’s really hard to share a Kubernetes cluster if you don’t have virtualization for Kubernetes. And that’s ultimately what we cluster adds on top of a Kubernetes cluster. It adds that virtual layer to give everybody their dedicated isolated space while it’s still sharing the underlying cluster and its node.
Robert Blumen 00:04:31 If I could summarize what you said, the key point about a virtual cluster to understand what is it, it is a Kubernetes cluster that runs inside of a host Kubernetes cluster and it does have some of its own services and then it shares the nodes with the host. Was there anything about that you’d like to correct?
Lukas Gentele 00:04:55 No, that’s an accurate summary. That’s exactly the idea. Some things are shared, certain things are completely isolated and that’s the beauty of the virtual cluster. You can mix and match, ultimately.
Robert Blumen 00:05:05 Does each vCluster have its own isolated control plane?
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