open-cluster-management/solutions/deploy-argocd-apps-pull/getting-started.md

Getting Started

Prerequisites

• kind must be installed on your local machine. The Kubernetes version must be >= 1.19. See the 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
  

• The kubectl cli, which should be compatible with your Kubernetes version. See install and setup for more info.

Steps

1. Setup an OCM Hub cluster and registered an OCM Managed cluster.

   curl -L https://raw.githubusercontent.com/open-cluster-management-io/OCM/main/solutions/setup-dev-environment/local-up.sh | bash
   

   See Open Cluster Management Quick Start for more details.

2. Install ArgoCD on the hub cluster and both managed clusters.

   for i in "hub" "cluster1" "cluster2"
   do
     kubectl config use-context kind-$i
     kubectl create namespace argocd
     kubectl apply -n argocd -f https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml
   done
   

   See ArgoCD website for more details.

3. Install the Pull controller on the hub cluster:

   kubectl config use-context kind-hub
   kubectl apply -f https://raw.githubusercontent.com/open-cluster-management-io/argocd-pull-integration/main/deploy/install.yaml
   

4. If your controller starts successfully, you should see:

   $ kubectl -n open-cluster-management get deploy | grep pull
   argocd-pull-integration-controller-manager   1/1     1            1           106s
   

5. On the Hub cluster, create ArgoCD cluster secrets that represent the managed clusters. This step can be automated with OCM auto import controller.

   for i in "cluster1" "cluster2"
   do
     cat <<EOF | kubectl apply -f -
     apiVersion: v1
     kind: Secret
     metadata:
       name: $i-secret # cluster1-secret
       namespace: argocd
       labels:
         argocd.argoproj.io/secret-type: cluster
     type: Opaque
     stringData:
       name: $i # cluster1
       server: https://$i-control-plane:6443 # https://cluster1-control-plane:6443
   EOF
   done
   

6. On the Hub cluster, apply the manifests in example/hub:

   kubectl config use-context kind-hub
   kubectl apply -f example/hub
   

7. On the managed clusters, apply the manifests in example/managed:

   for i in "cluster1" "cluster2"
   do
     kubectl config use-context kind-$i
     kubectl apply -f example/managed
   done
   

8. On the Hub cluster, apply the guestbook-app-set manifest:

   kubectl apply -f example/guestbook-app-set.yaml
   

   Note: The Application template inside the ApplicationSet must contain the following content:

         labels:
           apps.open-cluster-management.io/pull-to-ocm-managed-cluster: 'true'
         annotations:
           argocd.argoproj.io/skip-reconcile: 'true'
           apps.open-cluster-management.io/ocm-managed-cluster: '{{name}}'
   

   The label allows the pull model controller to select the Application for processing.

   The skip-reconcile annotation is to prevent the Application from reconciling on the Hub cluster.

   The ocm-managed-cluster annotation is for the ApplicationSet to generate multiple Application based on each cluster generator targets.

9. When this guestbook ApplicationSet reconciles, it will generate an Application for the registered managed clusters. For example:

   $ kubectl -n argocd get appset
   NAME            AGE
   guestbook-app   84s
   $ kubectl -n argocd get app
   NAME                     SYNC STATUS   HEALTH STATUS
   cluster1-guestbook-app   Synced        Healthy
   cluster2-guestbook-app   Synced        Healthy     
   

10. On the Hub cluster, the pull controller will wrap the Application with a ManifestWork. For example:

    $ kubectl -n cluster1 get manifestwork
    NAME                          AGE
    cluster1-guestbook-app-d0e5   2m41s
    

11. On a managed cluster, you should see that the Application is pulled down successfully. For example:

    $ kubectl -n argocd get app
    NAME                     SYNC STATUS   HEALTH STATUS
    cluster1-guestbook-app   Synced        Healthy
    $ kubectl -n guestbook get deploy
    NAME           READY   UP-TO-DATE   AVAILABLE   AGE
    guestbook-ui   1/1     1            1           7m36s
    

12. On the Hub cluster, the status controller will sync the dormant Application with the ManifestWork status feedback. For example:

    $ kubectl -n argocd get app
    NAME                     SYNC STATUS   HEALTH STATUS
    cluster1-guestbook-app   Synced        Healthy
    cluster2-guestbook-app   Synced        Healthy
    

If you have issues or need help troubleshooting, check out the troubleshooting guide