Cluster onboarding

Onboard an existing Kubernetes cluster to Greenhouse.

Content Overview

This guides describes how to onboard an existing Kubernetes cluster to your Greenhouse organization.
If you don’t have an organization yet please reach out to the Greenhouse administrators.

While all members of an organization can see existing clusters, their management requires org-admin or cluster-admin privileges.

NOTE: The UI is currently in development. For now this guide describes the onboarding workflow via command line.

Preparation

Download the latest greenhousectl binary from here.

Onboarding a Cluster to Greenhouse will require you to authenticate to two different Kubernetes clusters via respective kubeconfig files:

  • greenhouse: The cluster your Greenhouse installation is running on. You need organization-admin or cluster-admin privileges.
  • bootstrap: The cluster you want to onboard. You need system:masters privileges.

For consistency we will refer to those two clusters by their names from now on.

You need to have the kubeconfig files for both the greenhouse and the bootstrap cluster at hand. The kubeconfig file for the greenhouse cluster can be downloaded via the Greenhouse dashboard:

Organization > Clusters > Access Greenhouse cluster.

Onboard

For accessing the bootstrap cluster, the greenhousectl will expect your default Kubernetes kubeconfig file and context to be set to bootstrap. This can be achieved by passing the --kubeconfig flag or by setting the KUBECONFIG env var.

The location of the kubeconfig file to the greenhouse cluster is passed via the --greenhouse-kubeconfig flag.

greenhousectl cluster bootstrap --kubeconfig=<path/to/bootstrap-kubeconfig-file> --greenhouse-kubeconfig <path/to/greenhouse-kubeconfig-file> --org <greenhouse-organization-name> --cluster-name <name>

Since Greenhouse generates URLs which contain the cluster name, we highly recommend to choose a short cluster name. In particular for Gardener Clusters setting a short name is mandatory, because Gardener has very long cluster names, e.g. garden-greenhouse--monitoring-external.

A typical output when you run the command looks like

2024-02-01T09:34:55.522+0100	INFO	setup	Loaded kubeconfig	{"context": "default", "host": "https://api.greenhouse.tld"}
2024-02-01T09:34:55.523+0100	INFO	setup	Loaded client kubeconfig	{"host": "https://api.remote.tld"}
2024-02-01T09:34:56.579+0100	INFO	setup	Bootstraping cluster	{"clusterName": "monitoring", "orgName": "ccloud"}
2024-02-01T09:34:56.639+0100	INFO	setup	created namespace	{"name": "ccloud"}
2024-02-01T09:34:56.696+0100	INFO	setup	created serviceAccount	{"name": "greenhouse"}
2024-02-01T09:34:56.810+0100	INFO	setup	created clusterRoleBinding	{"name": "greenhouse"}
2024-02-01T09:34:57.189+0100	INFO	setup	created clusterSecret	{"name": "monitoring"}
2024-02-01T09:34:58.309+0100	INFO	setup	Bootstraping cluster finished	{"clusterName": "monitoring", "orgName": "ccloud"}

After onboarding

  1. List all clusters in your Greenhouse organization:
   kubectl --namespace=<greenhouse-organization-name> get clusters
  1. Show the details of a cluster:
   kubectl --namespace=<greenhouse-organization-name> get cluster <name> -o yaml

Example:

apiVersion: greenhouse.sap/v1alpha1
kind: Cluster
metadata:
  creationTimestamp: "2024-02-07T10:23:23Z"
  finalizers:
    - greenhouse.sap/cleanup
  generation: 1
  name: monitoring
  namespace: ccloud
  resourceVersion: "282792586"
  uid: 0db6e464-ec36-459e-8a05-4ad668b57f42
spec:
  accessMode: direct
  maxTokenValidity: 72h
status:
  bearerTokenExpirationTimestamp: "2024-02-09T06:28:57Z"
  kubernetesVersion: v1.27.8
  statusConditions:
    conditions:
      - lastTransitionTime: "2024-02-09T06:28:57Z"
        status: "True"
        type: Ready

When the status.kubernetesVersion field shows the correct version of the Kubernetes cluster, the cluster was successfully bootstrapped in Greenhouse. Then status.conditions will contain a Condition with type=Ready and status="true""

In the remote cluster, a new namespace is created and contains some resources managed by Greenhouse. The namespace has the same name as your organization in Greenhouse.

Troubleshooting

If bootstrapping fails, you can inspect the Cluster.statusConditions for more details. The type=KubeConfigValid condition may contain hints in the message field. Additional insights can be found in the type=PermissionsVerified and type=ManagedResourcesDeployed conditions, which indicate whether ServiceAccount has valid permissions and whether required resources were successfully deployed. These conditions are also visible in the UI on the Cluster details view. Reruning the onboarding command with an updated kubeConfig file will fix these issues.