Migrating Controllers
A controller can be moved from standalone mode to HA mode. It can also be returned from HA mode back to standalone mode.
Always Backup First!
Always back up controller configuration and create a database snapshot before attempting a migration.
Standalone to HA
Requirements
First, ensure that the controller's certificates and configuration meet the requirements.
- For certificate requirements see Bootstrapping/Certificates.
- For configuration requirements see Bootstrapping/Configuration.
Data Model Migration
The controller's data can be imported by using the db: setting in the config file.
Leave the db: </path/to/ctrl.db/> setting in the controller config. When the controller
starts up, it will see that it's running in HA mode, but isn't initialized yet. It will
try to use the database in the configuration to initialize its data model.
Once the controller is initialized, it should start up as normal and be usable. The cluster can now be expanded as explained in Operations/Growing the Cluster.
HA to Standalone
This assumes that you have a database snapshot from an HA cluster. This could either
be the ctrl-ha.db from the dataDir, or a snapshot created using the snapshot
CLI command.
To revert back to standalone mode, the raft section would be removed from the
config file and the db: section would be added back, pointing at the snapshot
from the HA cluster. Now when started, it should come up in standalone mode.