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Managing Server Roles

Starting the K3s server with --cluster-init will run all control-plane components, including the apiserver, controller-manager, scheduler, and etcd. It is possible to disable specific components in order to split the control-plane and etcd roles on to separate nodes.

정보

This document is only relevant when using embedded etcd. When not using embedded etcd, all servers will have the control-plane role and run control-plane components.

Dedicated etcd Nodes​

To create a server with only the etcd role, start K3s with all the control-plane components disabled:

curl -fL https://get.k3s.io | sh -s - server --cluster-init --disable-apiserver --disable-controller-manager --disable-scheduler

This first node will start etcd, and wait for additional etcd and/or control-plane nodes to join. The cluster will not be usable until you join an additional server with the control-plane components enabled.

Dedicated control-plane Nodes​

비고

A dedicated control-plane node cannot be the first server in the cluster; there must be an existing node with the etcd role before joining dedicated control-plane nodes.

To create a server with only the control-plane role, start k3s with etcd disabled:

curl -fL https://get.k3s.io | sh -s - server --token <token> --disable-etcd --server https://<etcd-only-node>:6443

After creating dedicated server nodes, the selected roles will be visible in kubectl get node:

$ kubectl get nodes
NAME           STATUS   ROLES                       AGE     VERSION
k3s-server-1   Ready    etcd                        5h39m   v1.20.4+k3s1
k3s-server-2   Ready    control-plane,master        5h39m   v1.20.4+k3s1

Adding Roles To Existing Servers​

Roles can be added to existing dedicated nodes by restarting K3s with the disable flags removed. For example ,if you want to add the control-plane role to a dedicated etcd node, you can remove the --disable-apiserver --disable-controller-manager --disable-scheduler flags from the systemd unit or config file, and restart the service.

Configuration File Syntax​

As with all other CLI flags, you can use the Configuration File to disable components, instead of passing the options as CLI flags. For example, to create a dedicated etcd node, you can place the following values in /etc/rancher/k3s/config.yaml:

cluster-init: true
disable-apiserver: true
disable-controller-manager: true
disable-scheduler: true