While currently those objects only get published by the kubelet for node-local
resources, this could change once we also support network-attached
resources. Dropping the "Node" prefix enables such a future extension.
The NodeName in ResourceSlice and StructuredResourceHandle then becomes
optional. The kubelet still needs to provide one and it must match its own node
name, otherwise it doesn't have permission to access ResourceSlice objects.
The information is received from the DRA driver plugin through a new gRPC
streaming interface. This is backwards compatible with old DRA driver kubelet
plugins, their gRPC server will return "not implemented" and that can be
handled by kubelet. Therefore no API break is needed.
However, DRA drivers need to be updated because the Go API changed. They can
return
status.New(codes.Unimplemented, "no node resource support").Err()
if they don't support the new ListAndWatchResources method and
structured parameters.
The controller in kubelet then synchronizes this information from the driver
with NodeResourceSlice objects, creating, updating and deleting them as needed.
If the resource handle has data from a structured parameter model, then we need
to pass that to the DRA driver kubelet plugin. Because Kubernetes uses
gogo/protobuf, we cannot use "optional" for that new optional field and have to
resort to "repeated" with a single repetition if present.
This is a new, backwards-compatible field.
That extending the resource.k8s.io changes the checksum of a kubelet checkpoint
is unfortunate. Updating the test cases is a stop-gap measure, the actual
solution will have to be something else before beta.
Like the current device plugin interface, a DRA driver using this model
announces a list of resource instances. In contrast to device plugins, this
list is made available to the scheduler together with attributes that can be
used to select suitable instances when they are not all alike.
Because this is the first structured parameter model, some checks that
previously were not possible, in particular "is one structured parameter field
set", now gets enabled. Adding another structured parameter model will be
similar.
The applyconfigs code generator assumes that all types in an API are defined in
a single package. If it wasn't for that, it would be possible to place the
"named resources" types in separate packages, which makes their names in the Go
code more natural and provides an indication of their stability level because
the package name could include a version.
NodeResourceSlice will be used by kubelet to publish resource information on
behalf of DRA drivers on the node. NodeName and DriverName in
NodeResourceSlice must be immutable. This simplifies tracking the different
objects because what they are for cannot change after creation.
The new field in ResourceClass tells scheduler and autoscaler that they are
expected to handle allocation.
ResourceClaimParameters and ResourceClassParameters are new types for telling
in-tree components how to handle claims.
