Advisory: See Swarm mode overview for the orchestration features introduced in Docker Engine 1.12. Only refer to the Docker Swarm documents below for information on the standalone Swarm product.
create command uses Docker Hub’s hosted discovery backend to create a unique discovery token for your cluster. For example:
$ docker run --rm swarm create 86222732d62b6868d441d430aee4f055
Later, when you use
join to create Swarm managers and nodes, you use the discovery token in the
<discovery> argument (e.g.,
token://86222732d62b6868d441d430aee4f055). The discovery backend registers each new Swarm manager and node that uses the token as a member of your cluster.
Some documentation also refers to the discovery token as a cluster_id.
Warning: Docker Hub’s hosted discovery backend is not recommended for production use. It’s intended only for testing/development.
For more information and examples about this and other discovery backends, see the Docker Swarm Discovery topic.