open-cluster-management/solutions/multiple-agents/README.md

Manage a spoke installed with multiple agents connected to different hubs

The scripts provided in this document help you set up an Open Cluster Management (OCM) environment with Kind clusters, where a single cluster is managed by two hubs via two agents installed on the managed cluster. The agents of the two hubs are all running in the default mode on the managed cluster under different namespaces.

Prerequisite

• kind must be installed on your local machine. The Kubernetes version must be >= 1.19, see kind user guide for more details.

• Download and install clusteradm. For Linux OS, run the following commands:

  wget -qO- https://github.com/open-cluster-management-io/clusteradm/releases/latest/download/clusteradm_linux_amd64.tar.gz | sudo tar -xvz -C /usr/local/bin/
  
  sudo chmod +x /usr/local/bin/clusteradm
  

Setup the first hub cluster

Run ./setup-hub1.sh. It creates two Kind clusters:

• hub1. It is initialized as a OCM hub cluster.
• cluster1. It joins the hub1 as a managed cluster.
  

Once it is done, you can then list the managed clusters on hub1 with command below.

kubectl get managedclusters
NAME       HUB ACCEPTED   MANAGED CLUSTER URLS                  JOINED   AVAILABLE   AGE
cluster1   true           https://cluster1-control-plane:6443                        29s

The managed cluster cluster1 joins hub1 in the default mode and its Klusterlet resource is created on the managed cluster.

kubectl get klusterlet
NAME         AGE
klusterlet   58s

And the OCM agent of hub1 is installed under namespace open-cluster-management-agent on the managed cluster. Another namespace open-cluster-management-agent-addon is created too for add-ons which might be installed in future for this managed cluster.

kubectl  get ns
NAME                                  STATUS   AGE
default                               Active   7m34s
kube-node-lease                       Active   7m34s
kube-public                           Active   7m34s
kube-system                           Active   7m34s
local-path-storage                    Active   7m30s
open-cluster-management               Active   7m27s
open-cluster-management-agent         Active   7m27s
open-cluster-management-agent-addon   Active   7m11s

Setup the second hub cluster

Run ./setup-hub2.sh to create one more Kind cluster hub2 and initialize it as the second OCM hub cluster. The script also joins the previously created Kind cluster cluster1 to hub2 as a managed cluster as well. Once it is done, you can list the managed clusters on hub2 with command below.

kubectl get managedclusters
NAME       HUB ACCEPTED   MANAGED CLUSTER URLS                  JOINED   AVAILABLE   AGE
cluster1   true           https://cluster1-control-plane:6443   True     True        30s

The managed cluster cluster1 joins hub2 in the default mode and its Klusterlet resource klusterlet-hub2 is created on the managed cluster as well.

kubectl get klusterlet
NAME              AGE
klusterlet        16m
klusterlet-hub2   1m

And the OCM agent of hub2 is installed under open-cluster-management-agent-hub2 on the managed cluster.

kubectl  get ns
NAME                                       STATUS   AGE
default                                    Active   19m
kube-node-lease                            Active   19m
kube-public                                Active   19m
kube-system                                Active   19m
local-path-storage                         Active   18m
open-cluster-management                    Active   18m
open-cluster-management-agent              Active   18m
open-cluster-management-agent-addon        Active   18m
open-cluster-management-agent-hub2         Active   105s
open-cluster-management-agent-hub2-addon   Active   105s