VCluster

Virtual K8S Clusters

"látszólagos fürt"
a rezsicsökkentett fölhő

2022. Október - Papp Lajos

0. What does it mean?
1. Use-cases
2. How does it work ?
3. Under the hood

lalyos

• mar az ovodaban in balna volt a jelem
• Cofounder of SequenceIQ (docker + bigdata + felho)
• BanzaiCloud in early times
• long time dev (java/golang) (since 1998)
• trainer/consultant (hire me!)

VCluster

A virtual k8s cluster which runs
in a namespace of a hosting cluster

Issues with k8s?

Issues with k8s?

• [dev] You got restricted acces

Issues with k8s?

• [dev] You got restricted acces
• [dev] Don't want to chage existing apps

Issues with k8s?

• [dev] You got restricted acces
• [dev] Don't want to chage existing apps
• [ops] Want less clusters to maintain

Real clusters

Moves

Virtual Clusters

Issues with k8s?

• [dev] You got restricted acces
• [dev] Don't want to chage existing apps
• [ops] Want less clusters to maintain
• [ops] Want Restrict acces by namspace

Issues with k8s?

• [dev] You got restricted acces
• [dev] Don't want to chage existing apps
• [ops] Want less clusters to maintain
• [ops] Want Restrict acces by namspace
• [ops] Parallely run different versoins of …

Issues with k8s?

• [dev] You got restricted acces
• [dev] Don't want to chage existing apps
• [ops] Want less clusters to maintain
• [ops] Want Restrict acces by namspace
• [ops] Parallely run different versoins of …
• … more …

• cloud provider APIServer customization ???
• Stop under-utilized clusters
• save costs (megvedjuk a magyar …)
• Everybody gets a cluster

Usage

• vcluster cli
• collect CIDR addr
• generate KUBECONFIG
• helm

RBAC: be able to start a pod

Exposing

• internal only
• NodePort
• Loadbalancer
• Ingress

Accessing a VCluster

$ > vcluster connect my-vcluster

generates KUBECONFIG yaml

How?

Vcluster has its own ctrl-plane

• APIServer
• Controller mgr
• Storage (etcd/kine)
• Scheduler ???

How k8s works normally:

training slides - thanks jpetazzo

KINE

Part/Subproject of K3S.io

Kine Is Not Etcd

Run Kubernetes on MySQL, Postgres, sqlite, dqlite, not etcd.

sqlite + litestream + s3 => dirt cheap,

Scheduler

By default you delegate it to the host cluster. But…

• Labeling nodes inside has no effect
• Draining or tainting nodes inside
• You cannot use custom schedulers inside

vcluster supports running a scheduler inside

DNS - Network

service mapping is configurable

Nodes

supports multiple sync modes:

• Fake Nodes (def)
• Real Nodes
• Real Nodes All
• Real Nodes Label Selector

daemonsets?

Synched Resources

pods, services, configmaps, secrets, events (other way), PVCs, Ingresses

configurable

sdk for custom resource syncers plugins (depl,sts,ns)

Extra Features

• Pausing & Resuming
• High Availability
• Distro choise: k3s/k0s/vanillia k8s
• Backup & Restore (Velero)

DinD / KinK

Keep in touch

• http://hwsw.lalyo.sh/