allow podman machine to extract its disk image from an oci registry or
oci-dir locally. for now, the image must be relatively inflexible. it
must have 1 layer. the layer must possess one image. so a dockerfile
like:
FROM scratch
COPY ./myimage.xz /myimage.xz
when using an oci dir, the directory structure must adhere to the
typical directory structure of a an oci image (with one layer).
── blobs
│ └── sha256
│ ├── 53735773573b3853bb1cae16dd21061beb416239ceb78d4ef1f2a0609f7e843b
│ ├── 80577866ec13c041693e17de61444b4696137623803c3d87f92e4f28a1f4e87b
│ └── af57637ac1ab12f833e3cfa886027cc9834a755a437d0e1cf48b5d4778af7a4e
├── index.json
└── oci-layout
in order to identify this new input, you must use a transport/schema to
differentiate from current podman machine init --image-path behavior. we
will support `oci-dir://` and `docker://` as transports.
when using the docker transport, you can only use an empty transport for
input. for example, `podman machine init --image-path docker://`. A
fully quailified image name will be supported in the next iteration.
the transport absent anything means, i want to pull the default fcos
image stored in a registry. podman will determine its current version
and then look for its correlating manifest. in this default use case,
it would look for:
quay.io/libpod/podman-machine-images:<version>
that manifest would then point to specific images that contain the
correct arch and provider disk image. i.e.
quay.io/libpod/podman-machine-images:4.6-qcow2
this PR does not enable something like
docker://quay.io/mycorp/myimage:latest yet.
names, addresses, andf schema/transports are all subject to change. the
plan is to keep this all undocumented until things firm up.
[NO NEW TESTS NEEDED]
Signed-off-by: Brent Baude <bbaude@redhat.com>
Brent Baude