Restore from a backup

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Restore DTR data

If your DTR has a majority of unhealthy replicas, the one way to restore it to a working state is by restoring from an existing backup.

To restore DTR, you need to:

  1. Stop any DTR containers that might be running
  2. Restore the images from a backup
  3. Restore DTR metadata from a backup
  4. Re-fetch the vulnerability database

You need to restore DTR on the same UCP cluster where you’ve created the backup. If you restore on a different UCP cluster, all DTR resources will be owned by users that don’t exist, so you’ll not be able to manage the resources, even though they’re stored in the DTR data store.

When restoring, you need to use the same version of the docker/dtr image that you’ve used when creating the update. Other versions are not guaranteed to work.

Remove DTR containers

Start by removing any DTR container that is still running:

$ docker container run \
  --rm \
  --interactive \
  docker/dtr:2.7.1 destroy \
  --ucp-insecure-tls

Restore images

If you had DTR configured to store images on the local filesystem, you can extract your backup:

sudo tar -xf dtr-image-backup.tar -C /var/lib/docker/volumes

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

Restore DTR metadata

You can restore the DTR metadata with the docker/dtr restore command. This performs a fresh installation of DTR, and reconfigures it with the configuration created during a backup.

Load your UCP client bundle, and run the following command, replacing the placeholders for the real values:

read -sp 'ucp password: ' UCP_PASSWORD;

This prompts you for the UCP password. Next, run the following to restore DTR from your backup. You can learn more about the supported flags in docker/dtr restore.

$ docker container run \
  --rm \
  --interactive \
  --env UCP_PASSWORD=$UCP_PASSWORD \
  docker/dtr:2.7.1 restore \
  --ucp-url <ucp-url> \
  --ucp-insecure-tls \
  --ucp-username <ucp-username> \
  --ucp-node <hostname> \
  --replica-id <replica-id> \
  --dtr-external-url <dtr-external-url> < dtr-metadata-backup.tar

Where:

  • <ucp-url> is the url you use to access UCP
  • <ucp-username> is the username of a UCP administrator
  • <hostname> is the hostname of the node where you’ve restored the images
  • <replica-id> the id of the replica you backed up
  • <dtr-external-url>the url that clients use to access DTR

DTR 2.5 and below

If you’re using NFS as a storage backend, also include --nfs-storage-url as part of your restore command, otherwise DTR is restored but starts using a local volume to persist your Docker images.

DTR 2.5 (with experimental online garbage collection) and DTR 2.6.0-2.6.3

When running DTR 2.5 (with experimental online garbage collection) and 2.6.0 to 2.6.3, there is an issue with reconfiguring and restoring DTR with --nfs-storage-url which leads to erased tags. Make sure to back up your DTR metadata before you proceed. To work around the --nfs-storage-urlflag issue, manually create a storage volume on each DTR node. To restore DTR from an existing backup, use docker/dtr restore with --dtr-storage-volume and the new volume. See Restore to a Local NFS Volume for Docker’s recommended recovery strategy.

Re-fetch the vulnerability database

If you’re scanning images, you now need to download the vulnerability database.

After you successfully restore DTR, you can join new replicas the same way you would after a fresh installation. Learn more.

Where to go next

dtr, disaster recovery