How to manage PKI and certificate lifetimes with Talos Linux

Talos Linux automatically manages and rotates all server side certificates for etcd, Kubernetes, and the Talos API. Note however that the kubelet needs to be restarted at least once a year in order for the certificates to be rotated. Any upgrade/reboot of the node will suffice for this effect.

You can check the Kubernetes certificates with the command talosctl get KubernetesDynamicCerts -o yaml on the controlplane.

Client certificates (talosconfig and kubeconfig) are the user’s responsibility. Each time you download the kubeconfig file from a Talos Linux cluster, the client certificate is regenerated giving you a kubeconfig which is valid for a year.

The talosconfig file should be renewed at least once a year, using the talosctl config new command, as shown below, or by one of the other methods.

Generating New Client Configuration

Using Controlplane Node

If you have a valid (not expired) talosconfig with os:admin role, a new client configuration file can be generated with talosctl config new against any controlplane node:

talosctl -n CP1 config new talosconfig-reader --roles os:reader --crt-ttl 24h

A specific role and certificate lifetime can be specified.

From Secrets Bundle

If a secrets bundle (secrets.yaml from talosctl gen secrets) was saved while generating machine configuration:

talosctl gen config --with-secrets secrets.yaml --output-types talosconfig -o talosconfig <cluster-name> https://<cluster-endpoint>

Note: <cluster-name> and <cluster-endpoint> arguments don’t matter, as they are not used for talosconfig.

From Control Plane Machine Configuration

In order to create a new key pair for client configuration, you will need the root Talos API CA. The base64 encoded CA can be found in the control plane node’s configuration file. Save the CA public key, and CA private key as ca.crt, and ca.key respectively:

yq eval controlplane.yaml | base64 -d > ca.crt
yq eval controlplane.yaml | base64 -d > ca.key

Now, run the following commands to generate a certificate:

talosctl gen key --name admin
talosctl gen csr --key admin.key --ip
talosctl gen crt --ca ca --csr admin.csr --name admin

Put the base64-encoded files to the respective location to the talosconfig:

context: mycluster
            - CP1
            - CP2
        ca: <base64-encoded ca.crt>
        crt: <base64-encoded admin.crt>
        key: <base64-encoded admin.key>