Manage AttachedCluster

In Kurator, clusters that are not created by Kurator are referred to as AttachedClusters. These clusters can be managed by adding them to the Kurator Fleet, expanding the fleet’s control to clusters not originally created by Kurator.

This guide will walk you through the process of creating AttachedCluster resources, using two Kind clusters as examples.

Prerequisites

Cluster operator

As the AttachedCluster object is controlled by the cluster-operator, you need to first go to Install cluster operator page to create clusters using hack/local-dev-setup.sh and install cluster operator.

AttachedCluster secrets

From these clusters created by hack/local-dev-setup.sh, we’ll select kurator-member1 and kurator-member2 to be attached to the Kurator Fleet.

If you didn’t create the corresponding cluster using our script, you need to change the kubeconfig file in which you created the cluster yourself. You can find your kubeconfig in /root/.kube/config, then Change the server field to the IP address of your cluster control plane node(you can get it from kubectl get nodes -owide) and the port number to 6443.

Next, we’ll create secrets containing the kubeconfig information of these clusters. Make sure to replace the paths like /root/.kube/kurator-member1.config with the actual kubeconfig file paths on your system.

kubectl create secret generic kurator-member1 --from-file=kurator-member1.config=/root/.kube/kurator-member1.config
kubectl create secret generic kurator-member2 --from-file=kurator-member2.config=/root/.kube/kurator-member2.config

Please note, here we have named the secrets as kurator-member1 and kurator-member2 respectively, and set the key to save the kubeconfig in the secret as kurator-member1.config and kurator-member2.config respectively. You can modify these two elements according to your needs.

Create attachedCluster resources

Now that we have the prerequisites sorted out, let’s move on to creating the AttachedCluster resources.

We’ll start by editing the configuration for the AttachedCluster.

Notice that the name and key here need to be consistent with the secret generated earlier.

We can apply the resources using the configuration provided below.

cat <<EOF | kubectl apply -f -
apiVersion: cluster.kurator.dev/v1alpha1
kind: AttachedCluster
metadata:
  name: kurator-member1
  namespace: default
spec:
  kubeconfig:
    name: kurator-member1
    key: kurator-member1.config
EOF

cat <<EOF | kubectl apply -f -
apiVersion: cluster.kurator.dev/v1alpha1
kind: AttachedCluster
metadata:
  name: kurator-member2
  namespace: default
spec:
  kubeconfig:
    name: kurator-member2
    key: kurator-member2.config
EOF

View resource status

Here is an example.

$ kubectl get attachedclusters.cluster.kurator.dev kurator-member1 -o yaml
kind: AttachedCluster
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"cluster.kurator.dev/v1alpha1","kind":"AttachedCluster","metadata":{"annotations":{},"name":"kurator-member1","namespace":"default"},"spec":{"kubeconfig":{"key":"kubeconfig","name":"kurator-member1"}}}
  creationTimestamp: "2023-05-27T09:41:36Z"
  generation: 1
  name: kurator-member1
  namespace: default
  resourceVersion: "28742"
  uid: 46199ce7-3829-4e0a-b1f7-46b47b8d421c
spec:
  kubeconfig:
    key: kurator-member1.config
    name: kurator-member1
status:
  ready: true

When we see ready: true in the status, it means that everything is as expected and the AttachedCluster is ready to be managed by Fleet.

If this is not the case, you can use the following command to check the reason.

kubectl logs -l app.kubernetes.io/name=kurator-cluster-operator -n kurator-system --tail=-1

Join with fleet

To join the AttachedClusters into a fleet, create the yaml like this:

cat <<EOF | kubectl apply -f -
apiVersion: fleet.kurator.dev/v1alpha1
kind: Fleet 
metadata:
  name: quickstart
  namespace: default
spec:
  clusters:
    # add your AttachedCluster here
    - name: kurator-member1 
      kind: AttachedCluster
    - name: kurator-member2
      kind: AttachedCluster
EOF

Cleanup

If you no longer need the AttachedClusters, you can delete them by running the following commands in the terminal:

kubectl delete attachedclusters.cluster.kurator.dev kurator-member1
kubectl delete attachedclusters.cluster.kurator.dev kurator-member2