Add config support for the pci feature source

User can now configure the list of device classes to detect, either via
a configuration file or by using the --options command line flag.

An example of a command line flag to detect all network controllers and
("main class 0x02) and VGA display controllers ("main" class 0x03 and
subclass 0x00) would be:
  --options='{"sources": {"pci": {"deviceClassWhitelist": ["02", "0300"] } } }'

README.md

@@ -189,8 +189,10 @@ format: `<class>_<vendor>`. E.g.
 node.alpha.kubernetes-incubator.io/nfd-pci-1200_8086.present=true
 ```
 
-Only device classes (0x)03, (0x)0b40 and (0x)12, i.e. GPUs, co-processors and
-accelerator cards are deteted.
+The set of PCI device classes that the feature source detects is configurable.
+By default, device classes (0x)03, (0x)0b40 and (0x)12, i.e. GPUs,
+co-processors and accelerator cards are deteted.
+See [configuration options](#configuration-options) for more information.
 
 ### RDT (Intel Resource Director Technology) Features
 
@@ -294,11 +296,16 @@ configuration in custom-built images.
 
 Configuration options can also be specified via the `--options` command line
 flag, in which case no mounts need to be used. The same format as in the config
-file must be used, i.e. JSON (or YAML).
-
+file must be used, i.e. JSON (or YAML). For example:
+```
+--options='{"sources": { "pci": { "deviceClassWhitelist": ["12"] } } }'
+```
 Configuration options specified from the command line will override those read
 from the config file.
 
+Currently, the only available configuration options are related to the
+[PCI feature source](#pci-features).
+
 ## Building from source
 
 Download the source code.

main.go

@@ -54,6 +54,7 @@ var (
 // Global config
 type NFDConfig struct {
 	Sources struct {
+		Pci *pci.NFDConfig `json:"pci,omitempty"`
 	} `json:"sources,omitempty"`
 }
 
@@ -206,6 +207,8 @@ func argsParse(argv []string) (args Args) {
 
 // Parse configuration options
 func configParse(filepath string, overrides string) error {
+	config.Sources.Pci = &pci.Config
+
 	data, err := ioutil.ReadFile(filepath)
 	if err != nil {
 		return fmt.Errorf("Failed to read config file: %s", err)

main_test.go

@@ -189,7 +189,10 @@ func TestConfigParse(t *testing.T) {
 		f, err := ioutil.TempFile("", "nfd-test-")
 		defer os.Remove(f.Name())
 		So(err, ShouldBeNil)
-		f.WriteString(`sources:`)
+		f.WriteString(`sources:
+  pci:
+    deviceClassWhitelist:
+      - "ff"`)
 		f.Close()
 
 		Convey("When proper config file is given", func() {
@@ -197,6 +200,7 @@ func TestConfigParse(t *testing.T) {
 
 			Convey("Should return error", func() {
 				So(err, ShouldBeNil)
+				So(config.Sources.Pci.DeviceClassWhitelist, ShouldResemble, []string{"ff"})
 			})
 		})
 	})

node-feature-discovery.conf.example

@@ -1 +1,6 @@
 #sources:
+#  pci:
+#    deviceClassWhitelist:
+#      - "0200"
+#      - "03"
+#      - "12"

source/pci/pci.go

@@ -29,7 +29,13 @@ type pciDeviceInfo map[string]string
 
 var logger = log.New(os.Stderr, "", log.LstdFlags)
 
-var deviceClassWhitelist = []string{"03", "0b40", "12"}
+type NFDConfig struct {
+	DeviceClassWhitelist []string `json:"deviceClassWhitelist,omitempty"`
+}
+
+var Config = NFDConfig{
+	DeviceClassWhitelist: []string{"03", "0b40", "12"},
+}
 
 // Implement FeatureSource interface
 type Source struct{}
@@ -47,8 +53,8 @@ func (s Source) Discover() ([]string, error) {
 	}
 
 	for class, classDevs := range devs {
-		for _, white := range deviceClassWhitelist {
-			if strings.HasPrefix(class, white) {
+		for _, white := range Config.DeviceClassWhitelist {
+			if strings.HasPrefix(class, strings.ToLower(white)) {
 				for _, dev := range classDevs {
 					features[fmt.Sprintf("%s_%s.present", dev["class"], dev["vendor"])] = true
 				}