Solution - Troubleshooting 'UUID has already been registered and has hostname' Error

Issue

Ondat nodes cannot successfully join the cluster due to the following error message » error verifying UUID: UUID aed3275f-846b-1f75-43a1-adbfec8bf974 has already been registered and has hostname 'debian-4', not 'node4' as demonstrated in the log entry below:

# Truncated output.
time="2018-09-24T13:47:02Z" level=error msg="failed to start api" error="error verifying UUID: UUID aed3275f-846b-1f75-43a1-adbfec8bf974 has already been registered and has hostname 'debian-4', not 'node4'" module=command

Root Cause

The Ondat registration process to start the cluster uses the hostname of the node where the Ondat container is running, provided by the kubelet.

• However, Ondat verifies the network hostname of the OS as a preflight check to make sure it can communicate with other nodes. If those names don’t match, Ondat is unable to start.

Resolution

Ensure that the hostnames match with the names advertised by your Kubernetes cluster.

• If you have changed the hostname of your nodes, ensure that you restart the nodes for changes to be applied successfully.