Having a store (edge) cluster join the datacenter (hub)

Allow ACM to deploy the store application to a subset of clusters

A store (“ATLANTA”) is installed on the hub cluster by default. This feature is interesting if you want to see how ACM can manage a remote cluster to install the same application on a different cluster.

The way we apply this is through the managedClusterGroups block in values-hub.yaml:

  managedClusterGroups:
  - name: store
    clusterSelector:
      matchLabels:
        clusterGroup: raleigh
      matchExpressions:
      - key: vendor
        operator: In
        values:
          - OpenShift

Any cluster joined with the label clusterGroup=raleigh will be assigned the policies that deploy the store app to them.

Deploy a store cluster

Rather than provide instructions on creating a store cluster it is assumed that an OpenShift cluster has already been created. Use the openshift-install program provided at cloud.redhat.com

There are a three ways to join the store to the datacenter.

Using the ACM user interface
Using the cm tool
Using the clusteradm tool

Store setup using the ACM UI

After ACM is installed a message regarding a “Web console update is available” may be displayed. Click on the “Refresh web console” link.

On the upper-left side you’ll see a pull down labeled “local-cluster”. Select “All Clusters” from this pull down. This will navigate to the ACM console and to its “Clusters” section

Select the “Import cluster” option beside the Create Cluster button.

import-cluster

On the “Import an existing cluster” page, enter the cluster name and choose Kubeconfig as the “import mode”. Add the tag site=store Press import. Done.

import-with-kubeconfig

Using this method, you are done. Skip to the section Store is joined but ignore the part about adding the site tag.

Store setup using `cm` tool

Install the cm (cluster management) command-line tool. See details here
Obtain the KUBECONFIG file from the edge/store cluster.
On the command-line login into the hub/datacenter cluster (use oc login or export the KUBECONFIG).
Run the following command:

cm attach cluster --cluster <cluster-name> --cluster-kubeconfig <path-to-KUBECONFIG>

Skip to the section Store is joined

Store setup using `clusteradm` tool

You can also use clusteradm to join a cluster. The following instructions explain what needs to be done. clusteradm is still in testing.

To deploy a edge cluster you will need to get the datacenter (or hub) cluster’s token. You will need to install clusteradm. On the existing datacenter cluster:
clusteradm get token
When you run the clusteradm command above it replies with the token and also shows you the command to use on the store. So first you must login to the store cluster
oc login or
export KUBECONFIG=~/my-ocp-env/store
Then request to that the store join the datacenter hub
clusteradm join --hub-token <token from clusteradm get token command > <store cluster name>
Back on the hub cluster accept the join request
clusteradm accept --clusters <store-cluster-name>

Skip to the next section, Store is joined

Store is joined

You’re done

That’s it! Go to your store (edge) OpenShift console and check for the open-cluster-management-agent pod being launched. Be patient, it will take a while for the ACM agent and agent-addons to launch. After that, the operator OpenShift GitOps will run. When it’s finished coming up launch the OpenShift GitOps (ArgoCD) console from the top right of the OpenShift console.