this pr represents a shift in how we download podman machine images.
these images will now be stored in oci registry and will replace the
default method of downloading an image. you can still use a reference
to a disk image as a path or url too with the --image-path switch.
the final registry and location of the images has not been determined;
and will need to be updated in podman as well.
i dont think we need to allow --image-path to accept a registry/image
for the podman 5.0 release. i do think there will be demand for this.
upgrades also need to be plumbed. for example, updating from an oci
registry.
once we make decisions on final image locations/registrties as well as
some behaviors of init and the oci pull, we must update the machine-init
documentation.
Signed-off-by: Brent Baude <bbaude@redhat.com>
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>
