nfd-master: prevent crash on empty config struct

Change the handling of LabelWhiteList config option to use a pointer to
detect when the option is unset. This doesn't fix any detected crash but
is merely general improvement and stabilization, serving easier testing.

Also, use the regexp type from the core libs for the config struct -
dropping the unmasrhalling code for our custom regexp type - as the core
regexp now implements unmarshaller itself.

Author: marquiz

pkg/nfd-master/nfd-master-internal_test.go

@@ -22,7 +22,6 @@ import (
 	"maps"
 	"os"
 	"path/filepath"
-	"regexp"
 	"sort"
 	"strings"
 	"testing"
@@ -108,7 +107,7 @@ func newFakeNfdAPIController(client *fakenfdclient.Clientset) *nfdController {
 func newFakeMaster(cli k8sclient.Interface) *nfdMaster {
 	return &nfdMaster{
 		nodeName:  testNodeName,
-		config:    &NFDConfig{LabelWhiteList: utils.RegexpVal{Regexp: *regexp.MustCompile("")}},
+		config:    &NFDConfig{},
 		k8sClient: cli,
 	}
 }

pkg/nfd-master/nfd-master.go

@@ -76,7 +76,7 @@ type NFDConfig struct {
 	AutoDefaultNs     bool
 	DenyLabelNs       utils.StringSetVal
 	ExtraLabelNs      utils.StringSetVal
-	LabelWhiteList    utils.RegexpVal
+	LabelWhiteList    *regexp.Regexp
 	NoPublish         bool
 	ResourceLabels    utils.StringSetVal
 	EnableTaints      bool
@@ -197,7 +197,6 @@ func NewNfdMaster(args *Args) (NfdMaster, error) {
 
 func newDefaultConfig() *NFDConfig {
 	return &NFDConfig{
-		LabelWhiteList:    utils.RegexpVal{Regexp: *regexp.MustCompile("")},
 		DenyLabelNs:       utils.StringSetVal{},
 		ExtraLabelNs:      utils.StringSetVal{},
 		NoPublish:         false,
@@ -608,8 +607,8 @@ func (m *nfdMaster) filterFeatureLabel(name, value string, features *nfdv1alpha1
 	}
 
 	// Skip if label doesn't match labelWhiteList
-	if !m.config.LabelWhiteList.Regexp.MatchString(base) {
-		return "", fmt.Errorf("%s (%s) does not match the whitelist (%s)", base, name, m.config.LabelWhiteList.Regexp.String())
+	if m.config.LabelWhiteList != nil && !m.config.LabelWhiteList.MatchString(base) {
+		return "", fmt.Errorf("%s (%s) does not match the whitelist (%s)", base, name, m.config.LabelWhiteList.String())
 	}
 
 	return filteredValue, nil
@@ -1210,7 +1209,7 @@ func (m *nfdMaster) configure(filepath string, overrides string) error {
 		c.EnableTaints = *m.args.Overrides.EnableTaints
 	}
 	if m.args.Overrides.LabelWhiteList != nil {
-		c.LabelWhiteList = *m.args.Overrides.LabelWhiteList
+		c.LabelWhiteList = &m.args.Overrides.LabelWhiteList.Regexp
 	}
 	if m.args.Overrides.ResyncPeriod != nil {
 		c.ResyncPeriod = *m.args.Overrides.ResyncPeriod

pkg/utils/flags.go

@@ -42,25 +42,6 @@ func (a *RegexpVal) Set(val string) error {
 	return err
 }
 
-// UnmarshalJSON implements the Unmarshaler interface from "encoding/json"
-func (a *RegexpVal) UnmarshalJSON(data []byte) error {
-	var v interface{}
-	if err := json.Unmarshal(data, &v); err != nil {
-		return err
-	}
-	switch val := v.(type) {
-	case string:
-		if r, err := regexp.Compile(string(val)); err != nil {
-			return err
-		} else {
-			*a = RegexpVal{*r}
-		}
-	default:
-		return fmt.Errorf("invalid regexp %s", data)
-	}
-	return nil
-}
-
 // StringSetVal is a Value encapsulating a set of comma-separated strings
 type StringSetVal map[string]struct{}