CODEWITHSUNDEEP
kubernetesk3sk3sup
PrestonDocks
PrestonDocks

Reputation: 5408

Can pods be deployed on k3s nodes with roles control-plane,etcd,master

I have followed this tutorial https://vmguru.com/2021/04/how-to-install-rancher-on-k3s/

At the end of it I end up with a running k3s cluster with 3 nodes

kubectl get nodes
NAME      STATUS   ROLES                       AGE     VERSION
master1   Ready    control-plane,etcd,master   7d20h   v1.23.5+k3s1
master2   Ready    control-plane,etcd,master   7d20h   v1.23.5+k3s1
master3   Ready    control-plane,etcd,master   7d20h   v1.23.5+k3s1

The cluster is using embeded etcd datastore

I am confused because I am able to deploy to workloads to this cluster. I thought I could only deploy workload to nodes with a role of Worker?

In other tutorials, the end result is master and worker roles on different nodes, so I am not even sure how I managed to get this combination of roles. Has something changed in the k3s distribution perhaps. The author used 1.19 I am using 1.23?

Upvotes: 0

Views: 1644

Answers (1)

ctholho
ctholho

Reputation: 1051

A node role is just a label. There are no specs that define what must happen if you use a label like role=control-plane.

While there are some well-known labels, among which you can find node role=control-plane, Kubernetes distributions (like k3s) don't have to follow these conventions.

kube-scheduler actually uses Taints and Tolerations do prevent workloads running on specific nodes. To see if a node has taints run kubectl describe node <node_name> and look for the taints field. If there are none, all workloads will run on them.

For single node clusters it's a necessary requirement that control plane components and normal workloads can run on the same machine. Even more so, putting cluster workloads on a different machine is just a best practice. Kubernetes distributions like k3s or microk8s were specifically build for smaller node clusters and disable taints by default.

Upvotes: 0

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