Start the control plane

Prerequisite

• The hub cluster should be v1.19+. (To run on hub cluster version between [v1.16, v1.18], please manually enable feature gate “V1beta1CSRAPICompatibility”).
• Currently the bootstrap process relies on client authentication via CSR. Therefore, if your Kubernetes distributions (like EKS) don’t support it, you can choose the multicluster-controlplane as the hub controlplane.
• Ensure kubectl and kustomize are installed.

Network requirements

Configure your network settings for the hub cluster to allow the following connections.

Install clusteradm CLI tool

It’s recommended to run the following command to download and install the latest release of the clusteradm command-line tool:

curl -L https://raw.githubusercontent.com/open-cluster-management-io/clusteradm/main/install.sh | bash

You can also install the latest development version (main branch) by running:

# Installing clusteradm to $GOPATH/bin/
GO111MODULE=off go get -u open-cluster-management.io/clusteradm/...

Bootstrap a cluster manager

Before actually installing the OCM components into your clusters, export the following environment variables in your terminal before running our command-line tool clusteradm so that it can correctly discriminate the hub cluster.

# The context name of the clusters in your kubeconfig
export CTX_HUB_CLUSTER=<your hub cluster context>

Call clusteradm init:

 # By default, it installs the latest release of the OCM components.
 # Use e.g. "--bundle-version=latest" to install latest development builds.
 # NOTE: For hub cluster version between v1.16 to v1.19 use the parameter: --use-bootstrap-token
 clusteradm init --wait --context ${CTX_HUB_CLUSTER}

The clusteradm init command installs the registration-operator on the hub cluster, which is responsible for consistently installing and upgrading a few core components for the OCM environment.

After the init command completes, a generated command is output on the console to register your managed clusters. An example of the generated command is shown below.

clusteradm join \
    --hub-token <your token data> \
    --hub-apiserver <your hub kube-apiserver endpoint> \
    --wait \
    --cluster-name <cluster_name>

It’s recommended to save the command somewhere secure for future use. If it’s lost, you can use clusteradm get token to get the generated command again.

Check out the running instances of the control plane

kubectl -n open-cluster-management get pod --context ${CTX_HUB_CLUSTER}
NAME                               READY   STATUS    RESTARTS   AGE
cluster-manager-695d945d4d-5dn8k   1/1     Running   0          19d

Additionally, to check out the instances of OCM’s hub control plane, run the following command:

kubectl -n open-cluster-management-hub get pod --context ${CTX_HUB_CLUSTER}
NAME                               READY   STATUS    RESTARTS   AGE
cluster-manager-placement-controller-857f8f7654-x7sfz      1/1     Running   0          19d
cluster-manager-registration-controller-85b6bd784f-jbg8s   1/1     Running   0          19d
cluster-manager-registration-webhook-59c9b89499-n7m2x      1/1     Running   0          19d
cluster-manager-work-webhook-59cf7dc855-shq5p              1/1     Running   0          19d
...

The overall installation information is visible on the clustermanager custom resource:

kubectl get clustermanager cluster-manager -o yaml --context ${CTX_HUB_CLUSTER}

Uninstall the OCM from the control plane

Before uninstalling the OCM components from your clusters, please detach the managed cluster from the control plane.

clusteradm clean --context ${CTX_HUB_CLUSTER}

Check the instances of OCM’s hub control plane are removed.

kubectl -n open-cluster-management-hub get pod --context ${CTX_HUB_CLUSTER}
No resources found in open-cluster-management-hub namespace.

kubectl -n open-cluster-management get pod --context ${CTX_HUB_CLUSTER}
No resources found in open-cluster-management namespace.

Check the clustermanager resource is removed from the control plane.

kubectl get clustermanager --context ${CTX_HUB_CLUSTER}
error: the server doesn't have a resource type "clustermanager"