Since version 6.3, Incus has been able to ingest OCI images. Docker
images conform to the OCI standard, meaning that docker images can
be downloaded and run in incus.

For each docker (or other) download site that is to be used, it is
necessary to add a 'remote' configuration to incus. To check what
remotes are currently configured, run:
    incus remote list

which (in a default installation) will show just 'image' and 'local'
remotes using 'simplestreams' and 'incus' protocols. To add a remote
for OCI protocol images from, say, hub.docker.com run the command:
    incus remote add docker https://docker.io --protocol=oci

Listing remotes should now show an additional remote named 'docker'
using the 'oci' protocol.

For the following examples of docker image ingestion, we'll use
docker images produced by Andrew Clemons and published at:
    https://hub.docker.com/r/aclemons/slackware

These are minimal Slackware images so don't take too long to download
and don't consume too much disk space.

Try:
    incus launch docker:aclemons/slackware:15.0 example-1

Notice that the resulting example-1 image is for an x86_64 (amd64)
system. What if a 32bit image is required instead? Luckily these
aclemons/slackware images are multi architecture (i386, amd64, arm/v7).
Any of these architectures can be selected by using the appropriate
image digest (the image for each architecture has its own distinct
digest). Find the digest for the i386 image and run:
    incus launch docker:aclemons/slackware@sha256:c4d50514d4f3922ef935946af48c6b44286723eb3974ca52e29baa4d2366614f example-2

Notice that the example-2 image contains i586 packages:
    incus exec example-2 -- ls -l /var/lib/pkgtools/packages

and uname -m returns 'i686':
    incus exec example-2 -- uname -m

i.e. example-2 is a 32bit Slackware 15.0


N.B. The image digest in the example above is correct at the time this
is written. It is likely to change whenever the image is updated.