Use modifier list and discoverModifer

This change uses modifier compositioning and the discoverModifier to
refactor the existing CSV modifier.

This change adds a discoverModifier to the internal/modifier package and
refactors the CSV modifier to use this abstraction.

Signed-off-by: Evan Lezar <elezar@nvidia.com>

cmd/nvidia-container-runtime/modifier/csv.go

@@ -24,10 +24,9 @@ import (
 	"github.com/NVIDIA/nvidia-container-toolkit/internal/cuda"
 	"github.com/NVIDIA/nvidia-container-toolkit/internal/discover"
 	"github.com/NVIDIA/nvidia-container-toolkit/internal/discover/csv"
-	"github.com/NVIDIA/nvidia-container-toolkit/internal/edits"
+	"github.com/NVIDIA/nvidia-container-toolkit/internal/modifier"
 	"github.com/NVIDIA/nvidia-container-toolkit/internal/oci"
 	"github.com/NVIDIA/nvidia-container-toolkit/internal/requirements"
-	"github.com/opencontainers/runtime-spec/specs-go"
 	"github.com/sirupsen/logrus"
 )
 
@@ -104,33 +103,22 @@ func NewCSVModifier(logger *logrus.Logger, cfg *config.Config, ociSpec oci.Spec)
 
 	d := discover.NewList(csvDiscoverer, ldcacheUpdateHook, createSymlinksHook)
 
-	return newModifierFromDiscoverer(logger, d)
+	return newCSVModifierFromDiscoverer(logger, d)
 }
 
-// newModifierFromDiscoverer created a modifier that aplies the discovered
+// newCSVModifierFromDiscoverer is used to test with dependency injection
-// modifications to an OCI spec if require by the runtime wrapper.
+func newCSVModifierFromDiscoverer(logger *logrus.Logger, d discover.Discover) (oci.SpecModifier, error) {
-func newModifierFromDiscoverer(logger *logrus.Logger, d discover.Discover) (oci.SpecModifier, error) {
+	discoverModifier, err := modifier.NewModifierFromDiscoverer(logger, d)
-	m := csvMode{
-		logger:     logger,
-		discoverer: d,
-	}
-	return &m, nil
-}
-
-// Modify applies the required modifications to the incomming OCI spec. These modifications
-// are applied in-place.
-func (m csvMode) Modify(spec *specs.Spec) error {
-	err := nvidiaContainerRuntimeHookRemover{m.logger}.Modify(spec)
 	if err != nil {
-		return fmt.Errorf("failed to remove existing hooks: %v", err)
+		return nil, fmt.Errorf("failed to construct modifier: %v", err)
 	}
 
-	specEdits, err := edits.NewSpecEdits(m.logger, m.discoverer)
+	modifiers := modifier.Merge(
-	if err != nil {
+		nvidiaContainerRuntimeHookRemover{logger},
-		return fmt.Errorf("failed to get required container edits: %v", err)
+		discoverModifier,
-	}
+	)
 
-	return specEdits.Modify(spec)
+	return modifiers, nil
 }
 
 func checkRequirements(logger *logrus.Logger, image *image.CUDA) error {

cmd/nvidia-container-runtime/modifier/csv_test.go

@@ -268,7 +268,7 @@ func TestExperimentalModifier(t *testing.T) {
 
 	for _, tc := range testCases {
 		t.Run(tc.description, func(t *testing.T) {
-			m, err := newModifierFromDiscoverer(logger, tc.discover)
+			m, err := newCSVModifierFromDiscoverer(logger, tc.discover)
 			require.NoError(t, err)
 
 			err = m.Modify(tc.spec)