Registration Operator: Minimum cluster registration and work

Registration Operator

The Registration Operator has 2 operators, Cluster Manager and Klusterlet. Cluster Manager installs the foundational components of OCM for the Hub cluster. And we can use the Klusterlet to install the agent components on the manged clusters when we import the manged clusters to the Hub.

The 2 operators are available on OperatorHub Cluster Manager and Klusterlet.

Concepts

Cluster Manager

The operator ClusterManager configures the controllers on the hub that govern registration, placement and work distribution for attached Klusterlets.

The controllers are all deployed in open-cluster-management-hub namespace on the Hub cluster.

Klusterlet

The operator Klusterlet represents the agent controllers registration and work on the managed cluster. The Klusterlet requires a secret named of bootstrap-hub-kubeconfig in the same namespace to allow API requests to the hub for the registration protocol.

The controllers are all deployed in open-cluster-management-agent namespace by default. The namespace can be specified in Klusterlet CR.

Get started with Kind

Create a cluster with kind
```
kind create cluster 
```

Deploy

export KUBECONFIG=$HOME/.kube/config
make deploy

More details about deployment

We mainly provide deployment in two scenarios:

All-in-one: using one cluster as hub and spoke at the same time.
Hub-spoke: using one cluster as hub and another cluster as spoke.

Deploy all-in-on deployment

Set an env variable KUBECONFIG to kubeconfig file path.
```
export KUBECONFIG=$HOME/.kube/config
```
Deploy all components on the cluster.
```
make deploy
```
To clean the environment, run make clean-deploy

Deploy hub-spoke deployment

Set env variables.
```
export KUBECONFIG=$HOME/.kube/config
```
Switch to hub context and deploy hub components.
```
kubectl config use-context {hub-context}
make deploy-hub
```
PLEASE NOTE: If you're running kubernetes in docker, the server address in kubeconfig may not be accessible for other clusters. In this case, you need to set HUB_KUBECONFIG explicitly.

For example, if your clusters are created by kind, you need to use kind's command to export a kubeconfig of hub with an accessible server address. (The related issue)
```
kind get kubeconfig --name {your kind cluster name} --internal > ./.hub-kubeconfig # ./.hub-kubeconfig is default value of HUB_KUBECONFIG 
```

Switch to spoke context and deploy agent components.

kubectl config use-context {spoke context}
make deploy-spoke

To clean the hub environment.

kubectl config use-context {hub-context} 
make clean-hub

To clean the spoke environment.

kubectl config use-context {spoke context} 
make clean-spoke

What is next

After a successful deployment, a certificatesigningrequest and a managedcluster will be created on the hub.

Switch to hub context and deploy hub components.

kubectl config use-context {hub-context}
kubectl get csr

Next approve the csr and set managedCluster to be accepted by hub with the following command

kubectl certificate approve {csr name}
kubectl patch managedcluster {cluster name} -p='{"spec":{"hubAcceptsClient":true}}' --type=merge
kubectl get managedcluster

Community, discussion, contribution, and support

Check the CONTRIBUTING Doc for how to contribute to the repo.

Communication channels

Slack channel: #open-cluster-mgmt

License

This code is released under the Apache 2.0 license. See the file LICENSE for more information.

GitHub

https://github.com/open-cluster-management-io/registration-operator

Registration Operator: Minimum cluster registration and work