Run only the images you trust

With Docker Universal Control Plane you can enforce applications to only use Docker images signed by UCP users you trust. When a user tries to deploy an application to the cluster, UCP checks if the application uses a Docker image that is not trusted, and won’t continue with the deployment if that’s the case.

By signing and verifying the Docker images, you ensure that the images being used in your cluster are the ones you trust and haven’t been altered either in the image registry or on their way from the image registry to your UCP swarm.

Example workflow

Here’s an example of a typical workflow:

1. A developer makes changes to a service and pushes their changes to a version control system.
2. A CI system creates a build, runs tests, and pushes an image to DTR with the new changes.
3. The quality engineering team pulls the image and runs more tests. If everything looks good they sign and push the image.
4. The IT operations team deploys a service. If the image used for the service was signed by the QA team, UCP deploys it. Otherwise UCP refuses to deploy.

Configure UCP

To configure UCP to only allow running services that use Docker images you trust, go to the UCP web UI, navigate to the Admin Settings page, and in the left pane, click Docker Content Trust.

Select the Run Only Signed Images option to only allow deploying applications if they use images you trust.

With this setting, UCP allows deploying any image as long as the image has been signed. It doesn’t matter who signed the image.

To enforce that the image needs to be signed by specific teams, click the dropdown and select those teams from the list.

Team must be in docker-datacenter

Select a team that’s part of the docker-datacenter organization to use this feature.

If you specify multiple teams, the image needs to be signed by a member of each team, or someone that is a member of all those teams, again which must be a part of the docker-datacenter organization.

Signing with teams

Teams used for signing policy enforcement must be in the docker-datacenter organization.

Click Save for UCP to start enforcing the policy. From now on, existing services will continue running and can be restarted if needed, but UCP will only allow deploying new services that use a trusted image.

Where to go next

• Sign and push images to DTR