This commit allows for loading an OCI image tarball before running an
OCI backed Shepherd service. It does so by adding a one shot Shepherd
service to the dependencies of the OCI backed service that at boot runs
docker load on the tarball.
* gnu/services/docker.scm (oci-image): New record;
(lower-oci-image): new variable, lower it;
(string-or-oci-image?): sanitize it;
(oci-container-configuration)[image]: allow also for oci-image records;
(oci-container-shepherd-service): use it;
(%oci-image-loader): new variable.
Change-Id: Ie504f479ea0d47f74b0ec5df9085673ffd3f639d
Signed-off-by: Ludovic Courtès <ludo@gnu.org>
c07731a777