mirror of https://github.com/docker/docs.git
135 lines
4.9 KiB
Markdown
135 lines
4.9 KiB
Markdown
---
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title: Scale your cluster
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description: Learn how to scale Docker Universal Control Plane cluster, by adding and removing nodes.
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keywords: UCP, cluster, scale
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---
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Docker UCP is designed for scaling horizontally as your applications grow in
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size and usage. You can add or remove nodes from the UCP cluster to make it
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scale to your needs.
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Since UCP leverages the clustering functionality provided by Docker Engine,
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you use the [docker swarm join](/engine/swarm/swarm-tutorial/add-nodes.md)
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command to add more nodes to your cluster. When joining new nodes, the UCP
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services automatically start running in that node.
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When joining a node to a cluster you can specify its role: manager or worker.
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* **Manager nodes**
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Manager nodes are responsible for swarm management functionality and
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dispatching tasks to worker nodes. Having multiple manager nodes allows
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your swarm to be highly-available and tolerate node failures.
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Manager nodes also run all UCP components in a replicated way, so by adding
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additional manager nodes, you're also making UCP highly available.
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[Learn more about the UCP architecture.](../../architecture.md)
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* **Worker nodes**
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Worker nodes receive and execute your services and applications. Having
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multiple worker nodes allows you to scale the computing capacity of your
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cluster.
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When deploying Docker Trusted Registry in your cluster, you deploy it to a
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worker node.
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## Join nodes to the cluster
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To join nodes to the swarm, go to the UCP web UI and navigate to the **Nodes**
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page.
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{: .with-border}
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Click **Add Node** to add a new node.
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{: .with-border}
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- Click **Manager** if you want to add the node as a manager.
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- Check the **Use a custom listen address** option to specify the
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IP address of the host that you want to join to the cluster.
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- Check the **Use a custom listen address** option to specify the
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IP address that's advertised to all members of the swarm for API access.
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Copy the displayed command, use ssh to log into the host that you want to
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join to the cluster, and run the `docker swarm join` command on the host.
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To add a Windows node, click **Windows** and follow the instructions in
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[Join Windows worker nodes to a swarm](join-windows-worker-nodes.md).
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After you run the join command in the node, the node is displayed in the UCP
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web UI.
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{: .with-border}
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## Pause or drain nodes
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Once a node is part of the cluster you can change its role making a manager
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node into a worker and vice versa. You can also configure the node availability
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so that it is:
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* Active: the node can receive and execute tasks.
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* Paused: the node continues running existing tasks, but doesn't receive new ones.
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* Drained: the node can't receive new tasks. Existing tasks are stopped and
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replica tasks are launched in active nodes.
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In the UCP web UI, browse to the **Nodes** page and select the node. In the
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details pane, click the **Configure** to open the **Edit Node** page.
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{: .with-border}
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## Promote or demote a node
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You can promote worker nodes to managers to make UCP fault tolerant. You can
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also demote a manager node into a worker.
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To promote or demote a manager node:
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1. Navigate to the **Nodes** page, and click the node that you want to demote.
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2. In the details pane, click **Configure** and select **Details** to open
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the **Edit Node** page.
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3. In the **Role** section, click **Manager** or **Worker**.
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4. Click **Save** and wait until the operation completes.
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5. Navigate to the **Nodes** page, and confirm that the node role has changed.
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If you're load-balancing user requests to Docker EE across multiple manager
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nodes, don't forget to remove these nodes from your load-balancing pool when
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you demote them to workers.
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## Remove a node from the cluster
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You can remove worker nodes from the cluster at any time:
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1. Navigate to the **Nodes** page and select the node.
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2. In the details pane, click **Actions** and select **Remove**.
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3. Click **Confirm** when you're prompted.
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Since manager nodes are important to the cluster overall health, you need to
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be careful when removing one from the cluster.
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To remove a manager node:
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1. Make sure all nodes in the cluster are healthy. Don't remove manager nodes
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if that's not the case.
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2. Demote the manager node into a worker.
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3. Now you can remove that node from the cluster.
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## Use the CLI to manage your nodes
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You can use the Docker CLI client to manage your nodes from the CLI. To do
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this, configure your Docker CLI client with a [UCP client bundle](../../../user-access/cli.md).
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Once you do that, you can start managing your UCP nodes:
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```bash
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docker node ls
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```
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## Where to go next
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* [Use your own TLS certificates](use-your-own-tls-certificates.md)
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* [Set up high availability](set-up-high-availability.md)
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