The software described in this documentation is either no longer supported or is in extended support.
Oracle recommends that you upgrade to a current supported release.

6.1.4 Promoting nodes to manager status

You can promote any worker nodes to manager status at any time by running the following command on an existing manager node:

# docker node promote ID|HOSTNAME

Substitute ID|HOSTNAME with the ID or hostname of the worker node that you wish to promote. For example, a worker node is promoted based on its docker ID:

# docker node promote 0eba8xkko48msqtx3talpbi4h

You can also demote manager nodes to return them back to worker-only status. In the following example, a manager node is demoted based on its hostname:

# docker node demote ol3.example.com

This command must be run on an alternate manager node, and not on the node that is being demoted. If only two nodes remain in manager status, you are unable to demote either node as quorum would be lost and the cluster would fail. Once you only have two nodes running in manager status, if the current manager leader goes offline, quorum is lost and the remaining manager is unable to promote itself to leader, resulting in a cluster failure. Therefore, a swarm should either only have a single manager or should have a minimum of three managers to maintain quorum for failover.