Add CSV-based discovery of device nodes

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

internal/discover/csv.go

@@ -54,41 +54,69 @@ func NewFromCSV(logger *logrus.Logger, csvRoot string, root string) (Discover, e
 	locators[csv.MountSpecSym] = symlinkLocator
 
 	var discoverers []Discover
-	// Create a discoverer for each file-kind combination
-	for _, file := range files {
-		targets, err := csv.ParseFile(logger, file)
+	for _, filename := range files {
+		d, err := NewFromCSVFile(logger, locators, filename)
 		if err != nil {
-			logger.Warnf("Skipping failed CSV file %v: %v", file, err)
+			logger.Warnf("Skipping CSV file %v: %v", filename, err)
 			continue
 		}
-		if len(targets) == 0 {
-			logger.Warnf("Skipping empty CSV file %v", file)
-			continue
-		}
-
-		candidatesByType := make(map[csv.MountSpecType][]string)
-		for _, t := range targets {
-			candidatesByType[t.Type] = append(candidatesByType[t.Type], t.Path)
-		}
-
-		for t, candidates := range candidatesByType {
-			d := csvDiscoverer{
-				filename:  file,
-				mountType: t,
-				mounts: mounts{
-					logger:   logger,
-					lookup:   locators[t],
-					required: candidates,
-				},
-			}
-			discoverers = append(discoverers, &d)
-		}
-
+		discoverers = append(discoverers, d)
 	}
 
 	return &list{discoverers: discoverers}, nil
 }
 
+// NewFromCSVFile creates a discoverer for the CSV file. A logger is also supplied.
+func NewFromCSVFile(logger *logrus.Logger, locators map[csv.MountSpecType]lookup.Locator, filename string) (Discover, error) {
+	// Create a discoverer for each file-kind combination
+	targets, err := csv.ParseFile(logger, filename)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse CSV file: %v", err)
+	}
+	if len(targets) == 0 {
+		return nil, fmt.Errorf("CSV file is empty")
+	}
+
+	csvDiscoverers, err := newFromMountSpecs(logger, locators, targets)
+	if err != nil {
+		return nil, err
+	}
+	var discoverers []Discover
+	for _, d := range csvDiscoverers {
+		d.filename = filename
+		discoverers = append(discoverers, d)
+	}
+
+	return &list{discoverers: discoverers}, nil
+}
+
+// newFromMountSpecs creates a discoverer for the CSV file. A logger is also supplied.
+func newFromMountSpecs(logger *logrus.Logger, locators map[csv.MountSpecType]lookup.Locator, targets []*csv.MountSpec) ([]*csvDiscoverer, error) {
+	var discoverers []*csvDiscoverer
+	candidatesByType := make(map[csv.MountSpecType][]string)
+	for _, t := range targets {
+		candidatesByType[t.Type] = append(candidatesByType[t.Type], t.Path)
+	}
+
+	for t, candidates := range candidatesByType {
+		locator, exists := locators[t]
+		if !exists {
+			return nil, fmt.Errorf("no locator defined for '%v'", t)
+		}
+		d := csvDiscoverer{
+			mounts: mounts{
+				logger:   logger,
+				lookup:   locator,
+				required: candidates,
+			},
+			mountType: t,
+		}
+		discoverers = append(discoverers, &d)
+	}
+
+	return discoverers, nil
+}
+
 func (d csvDiscoverer) Mounts() ([]Mount, error) {
 	if d.mountType == csv.MountSpecDev {
 		return d.None.Mounts()
@@ -96,3 +124,21 @@ func (d csvDiscoverer) Mounts() ([]Mount, error) {
 
 	return d.mounts.Mounts()
 }
+
+func (d csvDiscoverer) Devices() ([]Device, error) {
+	if d.mountType != csv.MountSpecDev {
+		return d.None.Devices()
+	}
+
+	mounts, err := d.mounts.Mounts()
+	if err != nil {
+		return nil, err
+	}
+	var devices []Device
+	for _, mount := range mounts {
+		device := Device(mount)
+		devices = append(devices, device)
+	}
+
+	return devices, nil
+}

internal/discover/csv_test.go

@@ -15,3 +15,172 @@
 **/
 
 package discover
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/NVIDIA/nvidia-container-toolkit/internal/discover/csv"
+	"github.com/NVIDIA/nvidia-container-toolkit/internal/lookup"
+	testlog "github.com/sirupsen/logrus/hooks/test"
+	"github.com/stretchr/testify/require"
+)
+
+func TestCSVDiscoverer(t *testing.T) {
+	logger, logHook := testlog.NewNullLogger()
+
+	testCases := []struct {
+		description          string
+		input                csvDiscoverer
+		expectedMounts       []Mount
+		expectedMountsError  error
+		expectedDevicesError error
+		expectedDevices      []Device
+	}{
+		{
+			description: "dev mounts are empty",
+			input: csvDiscoverer{
+				mounts: mounts{
+					lookup: &lookup.LocatorMock{
+						LocateFunc: func(string) ([]string, error) {
+							return []string{"located"}, nil
+						},
+					},
+					required: []string{"required"},
+				},
+				mountType: "dev",
+			},
+			expectedDevices: []Device{{Path: "located"}},
+		},
+		{
+			description: "dev devices returns error for nil lookup",
+			input: csvDiscoverer{
+				mountType: "dev",
+			},
+			expectedDevicesError: fmt.Errorf("no lookup defined"),
+		},
+		{
+			description: "lib devices are empty",
+			input: csvDiscoverer{
+				mounts: mounts{
+					lookup: &lookup.LocatorMock{
+						LocateFunc: func(string) ([]string, error) {
+							return []string{"located"}, nil
+						},
+					},
+					required: []string{"required"},
+				},
+				mountType: "lib",
+			},
+			expectedMounts: []Mount{{Path: "located"}},
+		},
+		{
+			description: "lib mounts returns error for nil lookup",
+			input: csvDiscoverer{
+				mountType: "lib",
+			},
+			expectedMountsError: fmt.Errorf("no lookup defined"),
+		},
+	}
+
+	for _, tc := range testCases {
+		logHook.Reset()
+
+		t.Run(tc.description, func(t *testing.T) {
+			tc.input.logger = logger
+
+			mounts, err := tc.input.Mounts()
+			if tc.expectedMountsError != nil {
+				require.Error(t, err)
+			} else {
+				require.NoError(t, err)
+			}
+			require.ElementsMatch(t, tc.expectedMounts, mounts)
+
+			devices, err := tc.input.Devices()
+			if tc.expectedDevicesError != nil {
+				require.Error(t, err)
+			} else {
+				require.NoError(t, err)
+			}
+			require.ElementsMatch(t, tc.expectedDevices, devices)
+		})
+	}
+}
+
+func TestNewFromMountSpec(t *testing.T) {
+	logger, _ := testlog.NewNullLogger()
+
+	locators := map[csv.MountSpecType]lookup.Locator{
+		"dev": &lookup.LocatorMock{},
+		"lib": &lookup.LocatorMock{},
+	}
+
+	testCases := []struct {
+		description            string
+		targets                []*csv.MountSpec
+		expectedError          error
+		expectedCSVDiscoverers []*csvDiscoverer
+	}{
+		{
+			description: "empty targets returns empyt list",
+		},
+		{
+			description: "unexpected locator returns error",
+			targets: []*csv.MountSpec{
+				{
+					Type: "foo",
+					Path: "bar",
+				},
+			},
+			expectedError: fmt.Errorf("no locator defined for foo"),
+		},
+		{
+			description: "creates discoverers based on type",
+			targets: []*csv.MountSpec{
+				{
+					Type: "dev",
+					Path: "dev0",
+				},
+				{
+					Type: "lib",
+					Path: "lib0",
+				},
+				{
+					Type: "dev",
+					Path: "dev1",
+				},
+			},
+			expectedCSVDiscoverers: []*csvDiscoverer{
+				{
+					mountType: "dev",
+					mounts: mounts{
+						logger:   logger,
+						lookup:   locators["dev"],
+						required: []string{"dev0", "dev1"},
+					},
+				},
+				{
+					mountType: "lib",
+					mounts: mounts{
+						logger:   logger,
+						lookup:   locators["lib"],
+						required: []string{"lib0"},
+					},
+				},
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.description, func(t *testing.T) {
+			discoverers, err := newFromMountSpecs(logger, locators, tc.targets)
+			if tc.expectedError != nil {
+				require.Error(t, err)
+				return
+			}
+			require.NoError(t, err)
+			require.ElementsMatch(t, tc.expectedCSVDiscoverers, discoverers)
+		})
+	}
+}

internal/discover/discover.go

@@ -16,6 +16,11 @@
 
 package discover
 
+// Device represents a discovered character device.
+type Device struct {
+	Path string
+}
+
 // Mount represents a discovered mount.
 type Mount struct {
 	Path string
@@ -29,8 +34,9 @@ type Hook struct {
 }
 
 //go:generate moq -stub -out discover_mock.go . Discover
-// Discover defines an interface for discovering the hooks and mounts available on a system
+// Discover defines an interface for discovering the devices, mounts, and hooks available on a system
 type Discover interface {
+	Devices() ([]Device, error)
 	Mounts() ([]Mount, error)
 	Hooks() ([]Hook, error)
 }

internal/discover/discover_mock.go

@@ -17,6 +17,9 @@ var _ Discover = &DiscoverMock{}
 //
 // 		// make and configure a mocked Discover
 // 		mockedDiscover := &DiscoverMock{
+// 			DevicesFunc: func() ([]Device, error) {
+// 				panic("mock out the Devices method")
+// 			},
 // 			HooksFunc: func() ([]Hook, error) {
 // 				panic("mock out the Hooks method")
 // 			},
@@ -30,6 +33,9 @@ var _ Discover = &DiscoverMock{}
 //
 // 	}
 type DiscoverMock struct {
+	// DevicesFunc mocks the Devices method.
+	DevicesFunc func() ([]Device, error)
+
 	// HooksFunc mocks the Hooks method.
 	HooksFunc func() ([]Hook, error)
 
@@ -38,6 +44,9 @@ type DiscoverMock struct {
 
 	// calls tracks calls to the methods.
 	calls struct {
+		// Devices holds details about calls to the Devices method.
+		Devices []struct {
+		}
 		// Hooks holds details about calls to the Hooks method.
 		Hooks []struct {
 		}
@@ -45,8 +54,39 @@ type DiscoverMock struct {
 		Mounts []struct {
 		}
 	}
-	lockHooks  sync.RWMutex
-	lockMounts sync.RWMutex
+	lockDevices sync.RWMutex
+	lockHooks   sync.RWMutex
+	lockMounts  sync.RWMutex
+}
+
+// Devices calls DevicesFunc.
+func (mock *DiscoverMock) Devices() ([]Device, error) {
+	callInfo := struct {
+	}{}
+	mock.lockDevices.Lock()
+	mock.calls.Devices = append(mock.calls.Devices, callInfo)
+	mock.lockDevices.Unlock()
+	if mock.DevicesFunc == nil {
+		var (
+			devicesOut []Device
+			errOut     error
+		)
+		return devicesOut, errOut
+	}
+	return mock.DevicesFunc()
+}
+
+// DevicesCalls gets all the calls that were made to Devices.
+// Check the length with:
+//     len(mockedDiscover.DevicesCalls())
+func (mock *DiscoverMock) DevicesCalls() []struct {
+} {
+	var calls []struct {
+	}
+	mock.lockDevices.RLock()
+	calls = mock.calls.Devices
+	mock.lockDevices.RUnlock()
+	return calls
 }
 
 // Hooks calls HooksFunc.

internal/discover/list.go

@@ -27,6 +27,21 @@ type list struct {
 
 var _ Discover = (*list)(nil)
 
+// Devices returns all devices from the included discoverers
+func (d list) Devices() ([]Device, error) {
+	var allDevices []Device
+
+	for i, di := range d.discoverers {
+		devices, err := di.Devices()
+		if err != nil {
+			return nil, fmt.Errorf("error discovering devices for discoverer %v: %v", i, err)
+		}
+		allDevices = append(allDevices, devices...)
+	}
+
+	return allDevices, nil
+}
+
 // Mounts returns all mounts from the included discoverers
 func (d list) Mounts() ([]Mount, error) {
 	var allMounts []Mount

internal/discover/mounts_test.go

@@ -26,6 +26,14 @@ import (
 	testlog "github.com/sirupsen/logrus/hooks/test"
 )
 
+func TestMountsReturnsEmptyDevices(t *testing.T) {
+	d := mounts{}
+	devices, err := d.Devices()
+
+	require.NoError(t, err)
+	require.Empty(t, devices)
+}
+
 func TestMounts(t *testing.T) {
 	logger, logHook := testlog.NewNullLogger()
 

internal/discover/none.go

@@ -22,6 +22,11 @@ type None struct{}
 
 var _ Discover = (*None)(nil)
 
+// Devices returns an empty list of devices
+func (e None) Devices() ([]Device, error) {
+	return []Device{}, nil
+}
+
 // Mounts returns an empty list of mounts
 func (e None) Mounts() ([]Mount, error) {
 	return []Mount{}, nil