What is a join token in Docker Swarm, and how is it used?

What is a join token in Docker Swarm, and how is it used?

In Docker Swarm, a join token is a special code created by the manager node when starting the Swarm. It's used to safely add worker nodes to the Swarm cluster.

You create the join token by running the docker swarm init command on the manager node. After setting it up, the command will show you the join token.

docker swarm join --token <worker-token> <manager-node-ip>:2377

Here's a breakdown of the components:

  • --token: Specifies the type of token, which can be either for worker nodes or manager nodes.

  • <worker-token>: A unique token that authenticates a worker node when joining the Swarm.

  • <manager-node-ip>: The IP address of the manager node, which is where the worker node should connect to join the Swarm.

To add a worker node to the Swarm, an administrator on the worker node uses the docker swarm join command with the right join token and the manager node's IP address. The worker node then connects to the manager, uses the token to authenticate, and joins the Swarm.

It's important to know that the join token is a secure way to let nodes join the Swarm, stopping unauthorized access. Also, join tokens can be changed or made again for better security.