Create a backup

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Data managed by DTR

Docker Trusted Registry maintains data about:

Data Description
Configurations The DTR cluster configurations
Repository metadata The metadata about the repositories and images deployed
Access control to repos and images Permissions for teams and repositories
Notary data Notary tags and signatures
Scan results Security scanning results for images
Certificates and keys The certificates, public keys, and private keys that are used for mutual TLS communication
Images content The images you push to DTR. This can be stored on the file system of the node running DTR, or other storage system, depending on the configuration

This data is persisted on the host running DTR, using named volumes. Learn more about DTR named volumes.

To perform a backup of a DTR node, run the docker/dtr backup command. This command backups up the following data:

Data Backed up Description
Configurations yes DTR settings
Repository metadata yes Metadata like image architecture and size
Access control to repos and images yes Data about who has access to which images
Notary data yes Signatures and digests for images that are signed
Scan results yes Information about vulnerabilities in your images
Certificates and keys yes TLS certificates and keys used by DTR
Image content no Needs to be backed up separately, depends on DTR configuration
Users, orgs, teams no Create a UCP backup to backup this data
Vulnerability database no Can be re-downloaded after a restore

Backup DTR data

To create a backup of DTR you need to:

  1. Backup image content
  2. Backup DTR metadata

You should always create backups from the same DTR replica, to ensure a smoother restore.

Backup image content

Since you can configure the storage backend that DTR uses to store images, the way you backup images depends on the storage backend you’re using.

If you’ve configured DTR to store images on the local file system or NFS mount, you can backup the images by using ssh to log into a node where DTR is running, and creating a tar archive of the dtr-registry volume:

sudo tar -cf {{ image_backup_file }} \
$(dirname $(docker volume inspect --format '{{.Mountpoint}}' dtr-registry-<replica-id>))

If you’re using a different storage backend, follow the best practices recommended for that system.

Backup DTR metadata

To create a DTR backup, load your UCP client bundle, and run the following command, replacing the placeholders for the real values:

read -sp 'ucp password: ' UCP_PASSWORD; \
docker run --log-driver none -i --rm \
  --env UCP_PASSWORD=$UCP_PASSWORD \
  docker/dtr:2.5.5 backup \
  --ucp-url <ucp-url> \
  --ucp-insecure-tls \
  --ucp-username <ucp-username> \
  --existing-replica-id <replica-id> > dtr-metadata-backup.tar

Where:

  • <ucp-url> is the url you use to access UCP.
  • <ucp-username> is the username of a UCP administrator.
  • <replica-id> is the id of the DTR replica to backup.

This prompts you for the UCP password, backups up the DTR metadata and saves the result into a tar archive. You can learn more about the supported flags in the reference documentation.

By default the backup command doesn’t stop the DTR replica being backed up. This allows performing backups without affecting your users. Since the replica is not stopped, it’s possible that happen while the backup is taking place, won’t be persisted.

You can use the --offline-backup option to stop the DTR replica while taking the backup. If you do this, remove the replica from the load balancing pool.

Also, the backup contains sensitive information like private keys, so you can encrypt the backup by running:

gpg --symmetric dtr-metadata-backup.tar

This prompts you for a password to encrypt the backup, copies the backup file and encrypts it.

Test your backups

To validate that the backup was correctly performed, you can print the contents of the tar file created. The backup of the images should look like:

tar -tf dtr-metadata-backup.tar

dtr-backup-v2.5.5/
dtr-backup-v2.5.5/rethink/
dtr-backup-v2.5.5/rethink/layers/

And the backup of the DTR metadata should look like:

tar -tf dtr-metadata-backup.tar

# The archive should look like this
dtr-backup-v2.5.5/
dtr-backup-v2.5.5/rethink/
dtr-backup-v2.5.5/rethink/properties/
dtr-backup-v2.5.5/rethink/properties/0

If you’ve encrypted the metadata backup, you can use:

gpg -d dtr-metadata-backup.tar | tar -t

You can also create a backup of a UCP cluster and restore it into a new cluster. Then restore DTR on that new cluster to confirm that everything is working as expected.

dtr, disaster recovery