new driver: kubernetes

Tested with `kind` and GKE.

Note: "nodes" shown in `docker buildx ls` are unrelated to Kubernetes "nodes".
Probably buildx should come up with an alternative term.

Usage:

  $ kind create cluster
  $ export KUBECONFIG="$(kind get kubeconfig-path --name="kind")"

  $ docker buildx create --driver kubernetes --driver-opt replicas=3 --use
  $ docker buildx build -t foo --load .

`--load` loads the image into the local Docker.

Driver opts:

  - `image=IMAGE` - Sets the container image to be used for running buildkit.
  - `namespace=NS` - Sets the Kubernetes namespace. Defaults to the current namespace.
  - `replicas=N` - Sets the number of `Pod` replicas. Defaults to 1.
  - `rootless=(true|false)` - Run the container as a non-root user without `securityContext.privileged`. Defaults to false.
  - `loadbalance=(sticky|random)` - Load-balancing strategy. If set to "sticky", the pod is chosen using the hash of the context path. Defaults to "sticky"

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

vendor/k8s.io/apimachinery/pkg/api/meta/interfaces.go

@@ -0,0 +1,134 @@
+/*
+Copyright 2014 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package meta
+
+import (
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/types"
+)
+
+type ListMetaAccessor interface {
+	GetListMeta() List
+}
+
+// List lets you work with list metadata from any of the versioned or
+// internal API objects. Attempting to set or retrieve a field on an object that does
+// not support that field will be a no-op and return a default value.
+type List metav1.ListInterface
+
+// Type exposes the type and APIVersion of versioned or internal API objects.
+type Type metav1.Type
+
+// MetadataAccessor lets you work with object and list metadata from any of the versioned or
+// internal API objects. Attempting to set or retrieve a field on an object that does
+// not support that field (Name, UID, Namespace on lists) will be a no-op and return
+// a default value.
+//
+// MetadataAccessor exposes Interface in a way that can be used with multiple objects.
+type MetadataAccessor interface {
+	APIVersion(obj runtime.Object) (string, error)
+	SetAPIVersion(obj runtime.Object, version string) error
+
+	Kind(obj runtime.Object) (string, error)
+	SetKind(obj runtime.Object, kind string) error
+
+	Namespace(obj runtime.Object) (string, error)
+	SetNamespace(obj runtime.Object, namespace string) error
+
+	Name(obj runtime.Object) (string, error)
+	SetName(obj runtime.Object, name string) error
+
+	GenerateName(obj runtime.Object) (string, error)
+	SetGenerateName(obj runtime.Object, name string) error
+
+	UID(obj runtime.Object) (types.UID, error)
+	SetUID(obj runtime.Object, uid types.UID) error
+
+	SelfLink(obj runtime.Object) (string, error)
+	SetSelfLink(obj runtime.Object, selfLink string) error
+
+	Labels(obj runtime.Object) (map[string]string, error)
+	SetLabels(obj runtime.Object, labels map[string]string) error
+
+	Annotations(obj runtime.Object) (map[string]string, error)
+	SetAnnotations(obj runtime.Object, annotations map[string]string) error
+
+	Continue(obj runtime.Object) (string, error)
+	SetContinue(obj runtime.Object, c string) error
+
+	runtime.ResourceVersioner
+}
+
+type RESTScopeName string
+
+const (
+	RESTScopeNameNamespace RESTScopeName = "namespace"
+	RESTScopeNameRoot      RESTScopeName = "root"
+)
+
+// RESTScope contains the information needed to deal with REST resources that are in a resource hierarchy
+type RESTScope interface {
+	// Name of the scope
+	Name() RESTScopeName
+}
+
+// RESTMapping contains the information needed to deal with objects of a specific
+// resource and kind in a RESTful manner.
+type RESTMapping struct {
+	// Resource is the GroupVersionResource (location) for this endpoint
+	Resource schema.GroupVersionResource
+
+	// GroupVersionKind is the GroupVersionKind (data format) to submit to this endpoint
+	GroupVersionKind schema.GroupVersionKind
+
+	// Scope contains the information needed to deal with REST Resources that are in a resource hierarchy
+	Scope RESTScope
+}
+
+// RESTMapper allows clients to map resources to kind, and map kind and version
+// to interfaces for manipulating those objects. It is primarily intended for
+// consumers of Kubernetes compatible REST APIs as defined in docs/devel/api-conventions.md.
+//
+// The Kubernetes API provides versioned resources and object kinds which are scoped
+// to API groups. In other words, kinds and resources should not be assumed to be
+// unique across groups.
+//
+// TODO: split into sub-interfaces
+type RESTMapper interface {
+	// KindFor takes a partial resource and returns the single match.  Returns an error if there are multiple matches
+	KindFor(resource schema.GroupVersionResource) (schema.GroupVersionKind, error)
+
+	// KindsFor takes a partial resource and returns the list of potential kinds in priority order
+	KindsFor(resource schema.GroupVersionResource) ([]schema.GroupVersionKind, error)
+
+	// ResourceFor takes a partial resource and returns the single match.  Returns an error if there are multiple matches
+	ResourceFor(input schema.GroupVersionResource) (schema.GroupVersionResource, error)
+
+	// ResourcesFor takes a partial resource and returns the list of potential resource in priority order
+	ResourcesFor(input schema.GroupVersionResource) ([]schema.GroupVersionResource, error)
+
+	// RESTMapping identifies a preferred resource mapping for the provided group kind.
+	RESTMapping(gk schema.GroupKind, versions ...string) (*RESTMapping, error)
+	// RESTMappings returns all resource mappings for the provided group kind if no
+	// version search is provided. Otherwise identifies a preferred resource mapping for
+	// the provided version(s).
+	RESTMappings(gk schema.GroupKind, versions ...string) ([]*RESTMapping, error)
+
+	ResourceSingularizer(resource string) (singular string, err error)
+}