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How do I change where my images are stored in DTR 2.x?

DTR 2.1.x and newer

Docker Trusted Registry stores its data in a volume that corresponds with its replica id. For example, the dtr-registry-000000000000 volume is where the DTR with replica id 000000000000 stores its registry data when using the filesystem backend.

To store your images in an NFS directory, specify the NFS URL at install time or switch to an NFS location after install with the reconfigure subcommand.

Details on this procedure are found in the docs:

To switch to a non-NFS storage location, you can specify the filesystem path of a manually-created volume name at install or reconfigure time. For example, to store the registry data at the /opt/registry/data location on the host filesystem, run the install command including the --dtr-storage-volume argument:

docker run --rm -it docker/dtr install --dtr-storage-volume /opt/registry/data ...

The dtr-registry-xxxxxxxxxxxx container will end up with /opt/registry/data as a BIND mount instead of using the dtr-registry-xxxxxxxxxxxx volume that the installer would otherwise create.

It is also possible to specify a volume instead of a host directory. For example, to specify a volume called registrydata on a DTR node, use the --dtr-storage-volume argument:

docker run --rm -it docker/dtr install --dtr-storage-volume registrydata ...

The --dtr-storage-volume option is also available when running docker/dtr reconfigure, so you can change the location that DTR uses after installation.

DTR 2.0.x

Docker Trusted Registry (DTR) shows a path such as /var/lib/docker/volumes/dtr-registry-000000000000/_data in what appears to be an editable text field, but it is grayed out. This text box is informational only. You can mount a filesystem at this location to store images in a different location.

To store your files at a different location:

  1. Use SSH to connect to the node running the DTR replica.
  2. Run the following command to find a volume called dtr-registry-$REPLICA_ID, where $REPLICA_ID corresponds to your twelve digit random hexadecimal DTR replica ID:
    docker volume ls
  3. Verify the proper location:
    docker inspect dtr-registry-$REPLICA_ID
    You should see a mount point listed. This should correspond with the grayed out value in the GUI.
  4. Mount your desired location as this location.

    For example, you can use NFS to mount a different filesystem to this location.

    mount -t nfs server:/path/on/server /var/lib/docker/volumes/dtr-registry-$REPLICA_ID/_data

    To use another location, use a BIND mount. For example:

    mount -o bind /path/on/system /var/lib/docker/volumes/dtr-registry-$REPLICA_ID/_data
  5. Once done, restart the Docker service on your system. Once it comes back up, your DTR images should now be served from this new location.

  6. Make sure to add the mount point into your /etc/fstab so that they are still available on next boot.