Introduce nfd client for image compatibilty

Makefile

@@ -90,7 +90,7 @@ IMAGE_BUILD_ARGS_MINIMAL = --target minimal \
 
 all: image
 
-BUILD_BINARIES := nfd-master nfd-worker nfd-topology-updater nfd-gc kubectl-nfd
+BUILD_BINARIES := nfd-master nfd-worker nfd-topology-updater nfd-gc kubectl-nfd nfd
 
 build-%:
 	$(GO_CMD) build -v -o bin/ $(BUILD_FLAGS) ./cmd/$*

api/image-compatibility/v1alpha1/spec.go

@@ -0,0 +1,48 @@
+/*
+Copyright 2024 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 v1alpha1
+
+import (
+	nfdv1alpha1 "sigs.k8s.io/node-feature-discovery/api/nfd/v1alpha1"
+)
+
+// ArtifactType is a type of OCI artifact that contains image compatibility metadata.
+const (
+	ArtifactType = "application/vnd.nfd.image-compatibility.v1alpha1"
+	Version      = "v1alpha1"
+)
+
+// Spec represents image compatibility metadata.
+type Spec struct {
+	// Version of the spec.
+	Version string `json:"version"`
+	// Compatibilities contains list of compatibility sets.
+	Compatibilties []Compatibility `json:"compatibilities"`
+}
+
+// Compatibility represents image compatibility metadata
+// that describe the image requirements for the host and OS.
+type Compatibility struct {
+	// Rules represents a list of Node Feature Rules.
+	Rules []nfdv1alpha1.Rule `json:"rules"`
+	// Weight indicates the priority of the compatibility set.
+	Weight int `json:"weight,omitempty"`
+	// Tag enables grouping or distinguishing between compatibility sets.
+	Tag string `json:"tag,omitempty"`
+	// Description of the compatibility set.
+	Description string `json:"description,omitempty"`
+}

api/nfd/v1alpha1/types.go

@@ -17,6 +17,9 @@ limitations under the License.
 package v1alpha1
 
 import (
+	"encoding/json"
+	"fmt"
+
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
@@ -296,6 +299,34 @@ type MatchExpression struct {
 	// In other cases Value should contain at least one element.
 	// +optional
 	Value MatchValue `json:"value,omitempty"`
+
+	// IsMatch indicates whether the processed expression matches the host.
+	// This field should not be exposed in the CRD or used by users.
+	// It is for informational purposes only.
+	IsMatch bool `json:"-"`
+}
+
+// Override MarshalJSON to hide the IsMatch field,
+// preventing users from accessing it and avoiding potential API confusion.
+// This field is returned only after rule processing to indicate if the expression matched the host.
+func (m *MatchExpression) MarshalJSON() ([]byte, error) {
+	if m.IsMatch {
+		return json.Marshal(struct {
+			MatchExpression
+			IsMatch bool `json:"isMatch"`
+		}{
+			*m, m.IsMatch,
+		})
+	}
+
+	return json.Marshal(*m)
+}
+
+func (m *MatchExpression) String() string {
+	if len(m.Value) < 1 {
+		return fmt.Sprintf("{op: %q}", m.Op)
+	}
+	return fmt.Sprintf("{op: %q, value: %q}", m.Op, m.Value)
 }
 
 // MatchOp is the match operator that is applied on values when evaluating a

cmd/nfd/main.go

@@ -0,0 +1,27 @@
+/*
+Copyright 2024 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 main
+
+import (
+	"sigs.k8s.io/node-feature-discovery/cmd/nfd/subcmd"
+)
+
+const ProgramName = "nfd"
+
+func main() {
+	subcmd.Execute()
+}

cmd/nfd/subcmd/compat/compat.go

@@ -0,0 +1,36 @@
+/*
+Copyright 2024 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 compat
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+var CompatCmd = &cobra.Command{
+	Use:   "compat",
+	Short: "Image compatibility commands",
+}
+
+func Execute() {
+	if err := CompatCmd.Execute(); err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+}

cmd/nfd/subcmd/compat/options/platform.go

@@ -0,0 +1,70 @@
+/*
+Copyright 2024 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 options
+
+import (
+	"fmt"
+	"runtime"
+	"strings"
+
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/spf13/cobra"
+)
+
+// PlatformOption represents
+type PlatformOption struct {
+	// PlatformStr contains the raw platform argument provided by the user.
+	PlatformStr string
+	// Platform represents the OCI platform specification, built from PlatformStr.
+	Platform *ocispec.Platform
+}
+
+// Parse takes the PlatformStr argument provided by the user
+// to build OCI platform specification.
+func (opt *PlatformOption) Parse(*cobra.Command) error {
+	var pStr string
+
+	if opt.PlatformStr == "" {
+		return nil
+	}
+
+	platform := &ocispec.Platform{}
+	pStr, platform.OSVersion, _ = strings.Cut(opt.PlatformStr, ":")
+	parts := strings.Split(pStr, "/")
+
+	switch len(parts) {
+	case 3:
+		platform.Variant = parts[2]
+		fallthrough
+	case 2:
+		platform.Architecture = parts[1]
+	case 1:
+		platform.Architecture = runtime.GOARCH
+	default:
+		return fmt.Errorf("failed to parse platform %q: expected format os[/arch[/variant]]", opt.PlatformStr)
+	}
+
+	platform.OS = parts[0]
+	if platform.OS == "" {
+		return fmt.Errorf("invalid platform: OS cannot be empty")
+	}
+	if platform.Architecture == "" {
+		return fmt.Errorf("invalid platform: Architecture cannot be empty")
+	}
+	opt.Platform = platform
+	return nil
+}