UCP architecture

Universal Control Plane is a containerized application that runs on Docker Enterprise Edition and extends its functionality to make it easier to deploy, configure, and monitor your applications at scale.

It also secures Docker with role-based access control so that only authorized users can make changes and deploy applications to your Docker cluster.

Once Universal Control Plane (UCP) is deployed, developers and IT operations no longer interact with Docker Engine directly, but interact with UCP instead. Since UCP exposes the standard Docker API this is all done transparently, so that you can use the tools you already know and love like the Docker CLI client and Docker Compose.

Under the hood

Docker UCP leverages the clustering and orchestration functionality provided by Docker.

A swarm is a collection of nodes that are in the same Docker swarm. Nodes in a Docker swarm operate in one of two modes: Manager or Worker. If nodes are not already running in a swarm when installing UCP, nodes will be configured to run in swarm mode.

When you deploy UCP, it starts running a globally scheduled service called ucp-agent. This service monitors the node where it is running and starts and stops UCP services, based on whether that node is a manager or a worker node.

If the node is a:

• Manager: the ucp-agent service automatically starts serving all UCP components including the UCP web UI and data stores used by UCP. The ucp-agent accomplishes this by deploying several containers on the node. By promoting a node to manager, UCP automatically becomes highly available and fault tolerant.
• Worker: on worker nodes the ucp-agent service starts serving a proxy service that ensures only authorized users and other UCP services can run Docker commands in that node. The ucp-agent only deploys a subset of containers on worker nodes.

UCP internal components

The core component of UCP is a globally-scheduled service called ucp-agent. When you install UCP on a node, or join a node to a swarm that is being managed by UCP, the ucp-agent service starts running on that node.

Once this service is running, it deploys containers with other UCP components, and ensures they keep running. The UCP components that are deployed on a node depend on whether that node is a manager or a worker.

UCP components in manager nodes

Manager nodes run all UCP services, including the web UI and data stores that persist the state of UCP. These are the UCP services running on manager nodes:

UCP components in worker nodes

Worker nodes are the ones where you run your applications. These are the UCP services running on worker nodes:

Volumes used by UCP

Docker UCP uses these named volumes to persist data in all nodes where it runs:

You can customize the volume driver used for these volumes, by creating the volumes before installing UCP. During the installation, UCP checks which volumes don’t exist in the node, and creates them using the default volume driver.

By default, the data for these volumes can be found at /var/lib/docker/volumes/<volume-name>/_data.

How you interact with UCP

There are two ways to interact with UCP: the web UI or the CLI.

You can use the UCP web UI to manage your cluster, grant and revoke user permissions, deploy, configure, manage, and monitor your applications.

UCP also exposes the standard Docker API, so you can continue using existing tools like the Docker CLI client. Since UCP secures your cluster with role-based access control, you need to configure your Docker CLI client and other client tools to authenticate your requests using client certificates that you can download from your UCP profile page.

Where to go next

• System requirements
• Plan your installation