Attach a cluster to your VMware Tanzu Mission Control organization that was previously attached and subsequently fell into a disconnected state.

Kubernetes clusters that are managed by Tanzu Mission Control can fall into a disconnected state, which means there has been no communication from the cluster to the cluster agent for an extended period of time. Sometimes this situation can be caused by environmental factors like network connectivity that are beyond the control of Tanzu Mission Control. However, sometimes a disconnected state can indicate that something was altered on the cluster that is preventing the Tanzu Mission Control cluster agent extensions from communicating with the cluster agent service.

The procedure described in this topic shows how to verify whether the connection is recoverable, and if so, how to reattach the cluster to your Tanzu Mission Control organization.

This procedure is also applicable for clusters on which you might have started, but never completed, the attach process and the client credentials have expired.

Prerequisites

You use both the Tanzu Mission Control console and the Tanzu Mission Control CLI to reattach a cluster.
  • Open a browser and log in to the Tanzu Mission Control console.
  • Open a command window and log in with the Tanzu Mission Control CLI.
Make sure you have the appropriate permissions.
  • To attach or reattach a cluster, you must be associated with the clustergroup.edit role on the cluster group in which you want to attach the cluster.
  • On the cluster, you must have admin permissions to install and run the cluster agent extensions.

Procedure

  1. In the Tanzu Mission Control console, navigate to the cluster you want to reattach.
    When an attached cluster is in a disconnected state, the cluster detail page displays a command that you can use to evaluate the condition of the cluster.
  2. On the cluster detail page, copy the displayed command.
    The command looks something like this: 
    tmc cluster validate -k <path_to_KUBECONFIG>
  3. In the command window, run the command, replacing <path_to_KUBECONFIG> with the path and name of your kubeconfig file for this cluster.
    The resulting ouput shows the tests that were run to determine the cause of the disconnect, and the tmc command that you can use to reattach the cluster. The command looks something like this: 
    tmc cluster reattach -n <CLUSTER_NAME> -k /path/to/kubeconfig
  4. In the command window, run the displayed command, replacing <CLUSTER_NAME> with the name of the cluster as displayed on cluster detail page in the Tanzu Mission Control console.

Results

The reattach command performs the necessary updates to the cluster agent extensions on the cluster to re-establish the connection between the cluster and the Tanzu Mission Control cluster agent.