Add FeatureFlags to the nvcdi API

This change adds support for feature flags to the nvcdi API.

A feature flag to disable nvsandboxutils is also added to allow
more flexibility in cases where this library causes issue.

Signed-off-by: Evan Lezar <[email protected]>

Author: elezar

pkg/nvcdi/api.go

@@ -45,3 +45,13 @@ const (
 	// This was added with v1.17.5 of the NVIDIA Container Toolkit.
 	HookEnableCudaCompat = HookName("enable-cuda-compat")
 )
+
+// A FeatureFlag refers to a specific feature that can be toggled in the CDI api.
+// All features are off by default.
+type FeatureFlag string
+
+const (
+	// FeatureDisableNvsandboxUtils disables the use of nvsandboxutils when
+	// querying devices.
+	FeatureDisableNvsandboxUtils = FeatureFlag("disable-nvsandbox-utils")
+)

pkg/nvcdi/lib.go

@@ -56,6 +56,8 @@ type nvcdilib struct {
 
 	mergedDeviceOptions []transform.MergedDeviceOption
 
+	featureFlags map[FeatureFlag]bool
+
 	disabledHooks disabledHooks
 	hookCreator   discover.HookCreator
 }
@@ -64,6 +66,7 @@ type nvcdilib struct {
 func New(opts ...Option) (Interface, error) {
 	l := &nvcdilib{
 		disabledHooks: make(disabledHooks),
+		featureFlags:  make(map[FeatureFlag]bool),
 	}
 	for _, opt := range opts {
 		opt(l)
@@ -218,6 +221,9 @@ func (l *nvcdilib) getCudaVersionNvsandboxutils() (string, error) {
 // getNvsandboxUtilsLib returns the nvsandboxutilslib to use for CDI spec
 // generation.
 func (l *nvcdilib) getNvsandboxUtilsLib() nvsandboxutils.Interface {
+	if l.featureFlags[FeatureDisableNvsandboxUtils] {
+		return nil
+	}
 	if l.nvsandboxutilslib != nil {
 		return l.nvsandboxutilslib
 	}

pkg/nvcdi/options.go

@@ -166,3 +166,14 @@ func WithDisabledHook(hook HookName) Option {
 		o.disabledHooks[hook] = true
 	}
 }
+
+// WithFeatureFlag allows specified features to be toggled on.
+// This option can be specified multiple times for each feature flag.
+func WithFeatureFlag(featureFlag FeatureFlag) Option {
+	return func(o *nvcdilib) {
+		if o.featureFlags == nil {
+			o.featureFlags = make(map[FeatureFlag]bool)
+		}
+		o.featureFlags[featureFlag] = true
+	}
+}