Customize an Application per Cluster

Prerequisites

Ensure you have reviewed the prerequisites section.

Enable a Custom Configuration of an Application for a Cluster

You can customize the application for each cluster occurrence of said application. If you want to customize the application for a cluster that is not yet attached, refer to the instructions below, so the application is deployed with the custom configuration on attachment.
To enable per-cluster customizations:

1. Reference the name of the ConfigMap to be applied per cluster in the spec.clusterConfigOverrides fields. In this example, you have three different customizations specified in three different ConfigMaps for three different clusters in one workspace:

   YAML

   cat <<EOF | kubectl apply -f -
   apiVersion: apps.kommander.d2iq.io/v1alpha3
   kind: AppDeployment
   metadata:
     name: kube-prometheus-stack
     namespace: ${WORKSPACE_NAMESPACE}
   spec:
     appRef:
       name: kube-prometheus-stack-44.2.1
       kind: ClusterApp
     clusterSelector:
       matchExpressions:
       - key: kommander.d2iq.io/cluster-name
         operator: In
         values:
         - attached-cluster1
         - attached-cluster2
         - attached-cluster3-new
     clusterConfigOverrides:
       - configMapName: kps-cluster1-overrides
         clusterSelector:
           matchExpressions:
           - key: kommander.d2iq.io/cluster-name
             operator: In
             values:
             - attached-cluster1
       - configMapName: kps-cluster2-overrides
         clusterSelector:
           matchExpressions:
           - key: kommander.d2iq.io/cluster-name
             operator: In
             values:
             - attached-cluster2
       - configMapName: kps-cluster3-overrides
         clusterSelector:
           matchExpressions:
           - key: kommander.d2iq.io/cluster-name
             operator: In
             values:
             - attached-cluster3-new
   EOF

2. If you have not done so yet, create the ConfigMaps referenced in each clusterConfigOverrides entry.

• The changes are applied only if the YAML file has a valid syntax.

• Set up only one cluster override ConfigMap per cluster. If there are several ConfigMaps configured for a cluster, only one will be applied.

• Cluster override ConfigMaps must be created on the Management cluster.

Enable a Custom Configuration of an Application for a Cluster at Attachment

You can customize the application configuration for a cluster prior to its attachment, so that the application is deployed with this custom configuration on attachment. This is preferable, if you do not want to redeploy the application with an updated configuration after it has been initially installed, which may cause downtime.

To enable per-cluster customizations, follow these steps before attaching the cluster:

1. Set the CLUSTER_NAME environment variable to the cluster name that you will give your to-be-attached cluster:

   CODE

   export CLUSTER_NAME=<your_attached_cluster_name>

2. Reference the name of the ConfigMap you want to apply to this cluster in the spec.clusterConfigOverrides fields. You do not need to update the spec.clusterSelector field. In this example, you have the kps-cluster1-overrides customization specified for attached-cluster-1 and a different customization (in kps-your-attached-cluster-overrides ConfigMap) for your to-be-attached cluster:

   YAML

   cat <<EOF | kubectl apply -f -
   apiVersion: apps.kommander.d2iq.io/v1alpha3
   kind: AppDeployment
   metadata:
     name: kube-prometheus-stack
     namespace: ${WORKSPACE_NAMESPACE}
   spec:
     appRef:
       name: kube-prometheus-stack-44.2.1
       kind: ClusterApp
     clusterSelector:
       matchExpressions:
       - key: kommander.d2iq.io/cluster-name
         operator: In
         values:
         - attached-cluster1
     clusterConfigOverrides:
       - configMapName: kps-cluster1-overrides
         clusterSelector:
           matchExpressions:
           - key: kommander.d2iq.io/cluster-name
             operator: In
             values:
             - attached-cluster1
       - configMapName: kps-your-attached-cluster-overrides
         clusterSelector:
           matchExpressions:
           - key: kommander.d2iq.io/cluster-name
             operator: In
             values:
             - ${CLUSTER_NAME}
   EOF

3. If you have not done so yet, create the ConfigMap referenced for your to-be-attached cluster.

• The changes are applied only if the YAML file has a valid syntax.

• Cluster override ConfigMaps must be created on the Management cluster.

Verify the Current Configuration of your Application

Refer to the Verify applications help to connect to the managed or attached cluster and check the status of the deployments. 

If you want to know how the AppDeployment resource is currently configured, refer to the Print and review the state of your AppDeployment section.