Cluster Registration Tokens

info

Not needed for Manager initiated registration: For manager initiated registrations the token is managed by the Fleet manager and does not need to be manually created and obtained.

For an agent initiated registration the downstream cluster must have a cluster registration token. Cluster registration tokens are used to establish a new identity for a cluster. Internally cluster registration tokens are managed by creating Kubernetes service accounts that have the permissions to create ClusterRegistrationRequests within a specific namespace. Once the cluster is registered a new ServiceAccount is created for that cluster that is used as the unique identity of the cluster. The agent is designed to forget the cluster registration token after registration. While the agent will not maintain a reference to the cluster registration token after a successful registration please note that usually other system bootstrap scripts do.

Since the cluster registration token is forgotten, if you need to re-register a cluster you must give the cluster a new registration token.

Token TTL

Cluster registration tokens can be reused by any cluster in a namespace. The tokens can be given a TTL such that it will expire after a specific time.

Create a new Token

The ClusterRegistationToken is a namespaced type and should be created in the same namespace in which you will create GitRepo and ClusterGroup resources. For in depth details on how namespaces are used in Fleet refer to the documentation on namespaces. Create a new token with the below YAML.

kind: ClusterRegistrationToken
apiVersion: "fleet.cattle.io/v1alpha1"
metadata:
    name: new-token
    namespace: clusters
spec:
    # A duration string for how long this token is valid for. A value <= 0 or null means infinite time.
    ttl: 240h

After the ClusterRegistrationToken is created, Fleet will create a corresponding Secret with the same name. As the Secret creation is performed asynchronously, you will need to wait until it’s available before using it.

One way to do so is via the following one-liner:

while ! kubectl --namespace=clusters  get secret new-token; do sleep 5; done

Obtaining Token Value (Agent values.yaml)

The token value contains YAML content for a values.yaml file that is expected to be passed to helm install to install the Fleet agent on a downstream cluster.

Such value is contained in the values field of the Secret mentioned above. To obtain the YAML content for the above example one can run the following one-liner:

kubectl --namespace clusters get secret new-token -o 'jsonpath={.data.values}' | base64 --decode > values.yaml

Once the values.yaml is ready it can be used repeatedly by clusters to register until the TTL expires.