Red Hat Advanced Cluster Management and OpenShift GitOps

A flexible way to manage OpenShift Gitops instances with RHACM.

Why this approach is worth considering

This repo is designed to enhance GitOps approach leveraged by OpenShift GitOps in a multi-cluster environment with business continuity process managed by RHACM.

How to use this repository

This is a boilerplate repository to quickly set up the initial resources.
It provides:

• Folder-based structure model
• RHACM objects
• OpenShift GitOps example objects

To start using this repo you can fork it and adapt it to your environment.

Repository structure model

This is a GitOps folder-based structure model.

• rhacm-manifests: contains Red Hat Advanced Cluster Management manifests.
• gitops-manifests
  • operator: contains OpenShift GitOps operator's manifests.
  • resources: contains Argo CD resources, such as AppProjects, Applications and ApplicationSets.

Why folder-based strategy and not branched-based

The folder-based approach has the following main advantages:

• The main branch is the Single Point of Truth for data
• Follows Git standard workflows
• Increase collaboration and the whole team enablement
• Avoids independent branches proliferation
• Reduces time during troubleshooting

Prerequisites

To use this repo you need to have in your enviroment:

• RHACM MultiClusterHub installed on an OpenShift Cluster.
• At least one OpenShift Cluster on which to install OpenShift Gitops operator.

How to deploy resources on RHACM Hub

• Login into RHACM Hub cluster.

• Deploy this repository on RHACM:

  oc apply -k https://github.com/amigliet/rhacm-gitops/rhacm-manifests/overlays/stage
  

  This will create the following resources:

  • Channel
  • PlacementRule
  • Subscription for OpenShift GitOps operator configurations
  • Subscription for Argo CD resources (i.e. AppProjects, Applications, ApplicationSets)
  • Application

Procedure to move OpenShift GitOps from Active to Backup OpenShift Cluster

First you need to have another OpenShift cluster on which you have installed OpenShift GitOps operator.
Then to switch from Active to Backup OpenShift cluster perform the following steps on RHACM:

• Delete apps Subscription.
  • To maintain Argo CD resources of the Application - such as Deployments, Services, etc - set the .spec.syncPolicy.preserveResourcesOnDeletion value to true in the parent ApplicationsSet, as follow:

    kind: ApplicationSet
    spec:
      generators:
        - clusters: {}
      template:
        # (...)
      syncPolicy:
        # Don't delete Application's child resources, on parent deletion:
        preserveResourcesOnDeletion: true
    

  • See Argo CD documentation on Application Deletion.
• Edit PlacementRule to deploy Argo CD to Backup cluster.
• Wait until Argo CD server status is Phase: Available on Backup cluster.
• Redeploy apps Subscription.