feat: add ability to export features for static node

For the HPC use case, we want to be able to export
static features to the terminal or JSON path.

Signed-off-by: vsoch <[email protected]>

Author: vsoch

cmd/nfd/subcmd/export/export.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 export
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+var ExportCmd = &cobra.Command{
+	Use:   "export",
+	Short: "Export features commands",
+}
+
+func Execute() {
+	if err := ExportCmd.Execute(); err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+}

cmd/nfd/subcmd/export/features.go

@@ -0,0 +1,102 @@
+/*
+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 export
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+
+	"github.com/spf13/cobra"
+
+	"sigs.k8s.io/node-feature-discovery/source"
+)
+
+var (
+	outputPath string
+)
+
+func NewExportCmd() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "features",
+		Short: "Export features for given node",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			sources := map[string]source.FeatureSource{}
+			for k, v := range source.GetAllFeatureSources() {
+				if ts, ok := v.(source.SupplementalSource); ok && ts.DisableByDefault() {
+					continue
+				}
+				sources[k] = v
+			}
+
+			// Discover all feature sources
+			for _, s := range sources {
+				if err := s.Discover(); err != nil {
+					fmt.Errorf("error during discovery of source %s: %w", s.Name(), err)
+					return err
+				}
+			}
+
+			// Make into flat format.
+			features := source.GetAllFeatures()
+			featureListing := map[string]string{}
+
+			// A flag's presence == true
+			for flagName := range features.Flags {
+				featureListing[flagName] = "true"
+			}
+
+			// Attributes are sets of elements (key value pairs)
+			for featureName, featureSet := range features.Attributes {
+				for elementName, elementValue := range featureSet.Elements {
+					featureListing[fmt.Sprintf("%s.%s", featureName, elementName)] = elementValue
+				}
+			}
+
+			for featureName, featureSet := range features.Instances {
+				for _, element := range featureSet.Elements {
+					for attrName, attrValue := range element.Attributes {
+						featureListing[fmt.Sprintf("%s.%s", featureName, attrName)] = attrValue
+					}
+				}
+			}
+			exportedLabels, err := json.MarshalIndent(featureListing, "", "    ")
+			if err != nil {
+				return err
+			}
+
+			if outputPath != "" {
+				fd, err := os.Create(outputPath)
+				if err != nil {
+					return err
+				}
+				defer fd.Close()
+				_, err = fmt.Fprint(fd, string(exportedLabels))
+				return err
+			} else {
+				fmt.Println(string(exportedLabels))
+			}
+			return nil
+		},
+	}
+	cmd.Flags().StringVar(&outputPath, "path", "", "export to this JSON path")
+	return cmd
+}
+
+func init() {
+	ExportCmd.AddCommand(NewExportCmd())
+}

cmd/nfd/subcmd/root.go

@@ -23,6 +23,7 @@ import (
 	"github.com/spf13/cobra"
 
 	"sigs.k8s.io/node-feature-discovery/cmd/nfd/subcmd/compat"
+	"sigs.k8s.io/node-feature-discovery/cmd/nfd/subcmd/export"
 )
 
 // RootCmd represents the base command when called without any subcommands
@@ -33,6 +34,7 @@ var RootCmd = &cobra.Command{
 
 func init() {
 	RootCmd.AddCommand(compat.CompatCmd)
+	RootCmd.AddCommand(export.ExportCmd)
 }
 
 // Execute adds all child commands to the root command and sets flags appropriately.

docs/usage/nfd-export.md

@@ -0,0 +1,35 @@
+---
+title: "Feature Export"
+layout: default
+sort: 12
+---
+
+# Feature Export
+{: .no_toc}
+
+## Table of contents
+{: .no_toc .text-delta}
+
+1. TOC
+{:toc}
+
+---
+
+## Feature Export
+
+**Feature export is in the experimental `v1alpha1` version.**
+
+If you are interested in exporting features in a generic context, the nfd client supports an export mode, where features can be derived without requiring a Kubernetes context.
+This addresses use cases such as high performance computing (HPC) and other environments with compute nodes that warrant assessment, but may not have Kubernetes running, or may not be able to or want to run a central daemon service for data. 
+To use export, you can use `nfd export features`:
+
+```bash
+nfd export features
+```
+
+By default, JSON structure with parsed key value pairs will appear in the terminal.
+To save to a file path:
+
+```bash
+nfd export features --path features.json
+```