Having a production cluster join the hub

Introduction

Production clusters need to be secured and so one part of the deployment is to install the Advanced Cluster Security operator with a secured configuration. This allows ACS central to monitor and report on security issues on the cluster. ACS secured sites report to an ACS Central application that is deployed on the hub.

Allow ACM to deploy the production application to a subset of secured clusters

By default the production applications are deployed on all prod clusters that ACM knows about.

  - name: secured
    helmOverrides:
    - name: clusterGroup.isHubCluster
      value: "false"
    clusterSelector:
      matchLabels:
        clusterGroup: prod
      matchExpressions:
      - key: vendor
        operator: In
        values:
          - OpenShift

Remember to commit the changes and push to GitHub so that GitOps can see your changes and apply them.

Deploy a production cluster

Rather than provide instructions on creating a production 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 production to the datacenter.

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

Production cluster 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.

update-web-console

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

launch-acm-console

Select the “Import cluster” option beside the highlighted 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 clusterGroup=prod Press import. Done.

import-with-kubeconfig

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

Production setup using `cm` tool

Install the cm (cluster management) command-line tool. See details here
Obtain the KUBECONFIG file from the managed production (prod) 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 Production is joined

Production 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 in production. So first you must login to the production cluster
oc login or
export KUBECONFIG=~/my-ocp-env/prod
Then request to that the production join the datacenter hub
clusteradm join --hub-token <token from clusteradm get token command > <production cluster name>
Back on the hub cluster accept the join request
clusteradm accept --clusters <production-cluster-name>

Skip to the next section, Production is joined

Production is joined

Designate the new cluster as a production site

Now that ACM is no longer deploying the production applications everywhere, we need to explicitly indicate that the new cluster has the production role. If you haven’t tagged the cluster as clusterGroup=prod then we can that here.

We do this by adding the label referenced in the managedSite’s clusterSelector.

Find the new cluster
oc get managedclusters.cluster.open-cluster-management.io
Apply the label
oc label managedclusters.cluster.open-cluster-management.io/YOURCLUSTER clusterGroup=prod

You’re done

That’s it! Go to your production 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.

Next up

Work your way through the Multicluster DevSecOps GitOps/DevOps demos (TBD)