Install using custom CA certificates and SA key pair

k0s generates all needed certificates automatically in the <data-dir>/pki directory (/var/lib/k0s/pki, by default).

But sometimes there is a need to have the CA certificates and SA key pair in advance. To make it work, just put files to the <data-dir>/pki and <data-dir>/pki/etcd:

export LIFETIME=365
mkdir -p /var/lib/k0s/pki/etcd
cd /var/lib/k0s/pki
openssl genrsa -out ca.key 2048
openssl req -x509 -new -nodes -key ca.key -sha256 -days $LIFETIME -out ca.crt -subj "/CN=Custom CA"
openssl genrsa -out sa.key 2048
openssl rsa -in sa.key -outform PEM -pubout -out sa.pub
cd ./etcd
openssl genrsa -out ca.key 2048
openssl req -x509 -new -nodes -key ca.key -sha256 -days $LIFETIME -out ca.crt -subj "/CN=Custom CA"

Then you can install k0s as usual.

Pre-generated tokens

It's possible to get join in advance without having a running cluster.

k0s token pre-shared --role worker --cert /var/lib/k0s/pki/ca.crt --url https://<controller-ip>:6443/

The command above generates a join token and a Secret. A Secret should be deployed to the cluster to authorize the token. For example, you can put the Secret under the manifest directory and it will be deployed automatically.

Please note that if you are generating a join token for a controller, the port number needs to be 9443 instead of 6443. Controller bootstrapping requires talking to the k0s-apiserver instead of the kube-apiserver. Here's an example of a command for pre-generating a token for a controller.

k0s token pre-shared --role controller --cert /var/lib/k0s/pki/ca.crt --url https://<controller-ip>:9443/