Wrap platforms.Only and fallback to our ignore mismatches due to empty
CPU variants. This just cleans things up and makes the logic re-usable
in other places.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
In some cases, in fact many in the wild, an image may have the incorrect
platform on the image config.
This can lead to failures to run an image, particularly when a user
specifies a `--platform`.
Typically what we see in the wild is a manifest list with an an entry
for, as an example, linux/arm64 pointing to an image config that has
linux/amd64 on it.
This change falls back to looking up the manifest list for an image to
see if the manifest list shows the image as the correct one for that
platform.
In order to accomplish this we need to traverse the leases associated
with an image. Each image, if pulled with Docker 20.10, will have the
manifest list stored in the containerd content store with the resource
assigned to a lease keyed on the image ID.
So we look up the lease for the image, then look up the assocated
resources to find the manifest list, then check the manifest list for a
platform match, then ensure that manifest referes to our image config.
This is only used as a fallback when a user specified they want a
particular platform and the image config that we have does not match
that platform.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
This fixes a regression based on expectations of the runtime:
```
docker pull arm32v7/alpine
docker run arm32v7/alpine
```
Without this change, the `docker run` will fail due to platform
matching on non-arm32v7 systems, even though the image could run
(assuming the system is setup correctly).
This also emits a warning to make sure that the user is aware that a
platform that does not match the default platform of the system is being
run, for the cases like:
```
docker pull --platform armhf busybox
docker run busybox
```
Not typically an issue if the requests are done together like that, but
if the image was already there and someone did `docker run` without an
explicit `--platform`, they may very well be expecting to run a native
version of the image instead of the armhf one.
This warning does add some extra noise in the case of platform specific
images being run, such as `arm32v7/alpine`, but this can be supressed by
explicitly setting the platform.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
This enables image lookup when creating a container to fail when the
reference exists but it is for the wrong platform. This prevents trying
to run an image for the wrong platform, as can be the case with, for
example binfmt_misc+qemu.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
