Docker EE is designed for scaling horizontally as your applications grow in -size and usage. You can add or remove nodes from the cluster to scale it -to your needs. You can join Windows Server 2016, IBM z System, and Linux nodes -to the cluster.
- -Because Docker EE leverages the clustering functionality provided by Docker -Engine, you use the docker swarm join -command to add more nodes to your cluster. When you join a new node, Docker EE -services start running on the node automatically.
- -When you join a node to a cluster, you specify its role: manager or worker.
- -Manager: Manager nodes are responsible for cluster management -functionality and dispatching tasks to worker nodes. Having multiple -manager nodes allows your swarm to be highly available and tolerant of -node failures.
- -Manager nodes also run all Docker EE components in a replicated way, so -by adding additional manager nodes, you’re also making the cluster highly -available. -Learn more about the Docker EE architecture.
-Worker: Worker nodes receive and execute your services and applications. -Having multiple worker nodes allows you to scale the computing capacity of -your cluster.
- -When deploying Docker Trusted Registry in your cluster, you deploy it to a -worker node.
-You can join Windows Server 2016, IBM z System, and Linux nodes to the cluster, -but only Linux nodes can be managers.
- -To join nodes to the cluster, go to the Docker EE web UI and navigate to the -Nodes page.
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Copy the displayed command, use SSH to log in to the host that you want to
-join to the cluster, and run the docker swarm join command on the host.
To add a Windows node, click Windows and follow the instructions in -Join Windows worker nodes to a cluster.
- -After you run the join command in the node, the node is displayed on the -Nodes page in the Docker EE web UI. From there, you can change the node’s -cluster configuration, including its assigned orchestrator type. -Learn how to change the orchestrator for a node.
- -Once a node is part of the cluster, you can configure the node’s availability -so that it is:
- -Pause or drain a node from the Edit Node page:
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You can promote worker nodes to managers to make UCP fault tolerant. You can -also demote a manager node into a worker.
- -To promote or demote a manager node:
- -If you’re load-balancing user requests to Docker EE across multiple manager -nodes, don’t forget to remove these nodes from your load-balancing pool when -you demote them to workers.
- -You can remove worker nodes from the cluster at any time:
- -Since manager nodes are important to the cluster overall health, you need to -be careful when removing one from the cluster.
- -To remove a manager node:
- -You can use the Docker CLI client to manage your nodes from the CLI. To do -this, configure your Docker CLI client with a UCP client bundle.
- -Once you do that, you can start managing your UCP nodes:
- -docker node ls
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