multicluster-global-hub

README

Multicluster Global Hub Overview

This document attempts to explain how the different components in multicluster global hub come together to deliver multicluster management at very high scale. The multicluster-global-hub operator is the root operator which pulls in all things needed.

Conceptual Diagram

Multicluster Global Hub Operator

Operator is for multicluster global hub. It is used to deploy all required components for multicluster management. The components include multicluster-global-hub-manager in the global hub cluster and multicluster-global-hub-agent in the regional hub clusters.

The Operator also leverages the manifestwork to deploy the Advanced Cluster Management for Kubernetes in the managed cluster. So the managed cluster is switched to a standard ACM Hub cluster (regional hub cluster).

Multicluster Global Hub Manager

The manager is used to persist the data into the postgreSQL. The data is from Kafka transport. The manager is also used to post the data to Kafka transport so that it can be synced to the regional hub clusters.

Multicluster Global Hub Agent

The agent is running in the regional hub clusters. It is responsible to sync-up the data between the global cluster hub and the regional hub clusters. For instance, sync-up the managed clusters' info from the regional hub clusters to the global hub cluster and sync-up the policy or application from the global hub cluster to the regional hub clusters.

Quick Start Guide

Prerequisites

1. Connect to a Kubernetes cluster with kubectl
2. ACM or OCM is installed on the Kubernetes cluster
3. PostgreSQL is installed and a database is created for the multicluster global hub. A secret storage-secret contains the credential is created in open-cluster-management namespace. The credential format like postgres://<user>:<password>@<host>:<port>/<database>:

kubectl create secret generic storage-secret -n "open-cluster-management" \
    --from-literal=database_uri=<postgresql-uri> 

You can run this sample script ./operator/config/samples/storage/deploy_postgres.sh to install postgres in hoh-postgres namespace and create the secret storage-secret in namespace open-cluster-management automatically.

1. Kafka is installed and two topics spec and status are created, also a secret with name transport-secret that contains the kafka access information should be created in open-cluster-management namespace:

kubectl create secret generic transport-secret -n "open-cluster-management" \
    --from-literal=bootstrap_server=<kafka-bootstrap-server-address> \
    --from-literal=CA=<CA-for-kafka-server>

As above, You can run this sample script ./operator/config/samples/transport/deploy_kafka.sh to install kafka in kafka namespace and create the secret transport-secret in namespace open-cluster-management automatically.

Run the operator in the cluster

Note: You can also install Multicluster Global Hub Operator from Operator Hub if you have ACM installed in an OpenShift Container Platform, the operator can be found in community operators by searching "multicluster global hub" keyword in the filter box, then follow the document to install the operator.

Follow the steps below to instal Multicluster Global Hub Operator in developing environment:

1. Check out the multicluster-global-hub repository

git clone git@github.com:stolostron/multicluster-global-hub.git
cd multicluster-global-hub/operator

1. Build and push your image to the location specified by IMG:

make docker-build docker-push IMG=<some-registry>/multicluster-global-hub-operator:<tag>

1. Deploy the controller to the cluster with the image specified by IMG:

make deploy IMG=<some-registry>/multicluster-global-hub-operator:<tag>

1. Install instance of custom resource:

kubectl apply -k config/samples/

Uninstall the operator

1. Delete the multicluster-global-hub-operator CR:

kubectl delete mgh --all

1. Delete the multicluster-global-hub-operator:

make undeploy

1. To delete the multicluster global hub CRD from the cluster:

make uninstall

Contributing

Go to the Contributing guide to learn how to get involved.