merge SMART_DEVICES with devices returned from smartctl scan

agent/smart.go

@@ -136,17 +136,19 @@ func (sm *SmartManager) ScanDevices(force bool) error {
 	}
 	sm.lastScanTime = time.Now()
 
-	if configuredDevices, ok := GetEnv("SMART_DEVICES"); ok {
+	var configuredDevices []*DeviceInfo
-		config := strings.TrimSpace(configuredDevices)
+	if configuredRaw, ok := GetEnv("SMART_DEVICES"); ok {
+		config := strings.TrimSpace(configuredRaw)
 		if config == "" {
 			return errNoValidSmartData
 		}
 		slog.Info("SMART_DEVICES", "config", config)
 
-		if err := sm.parseConfiguredDevices(config); err != nil {
+		parsedDevices, err := sm.parseConfiguredDevices(config)
+		if err != nil {
 			return err
 		}
-		return nil
+		configuredDevices = parsedDevices
 	}
 
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
@@ -155,18 +157,34 @@ func (sm *SmartManager) ScanDevices(force bool) error {
 	cmd := exec.CommandContext(ctx, "smartctl", "--scan", "-j")
 	output, err := cmd.Output()
 
+	var (
+		scanErr        error
+		scannedDevices []*DeviceInfo
+		hasValidScan   bool
+	)
+
 	if err != nil {
-		return err
+		scanErr = err
+	} else {
+		scannedDevices, hasValidScan = sm.parseScan(output)
+		if !hasValidScan {
+			scanErr = errNoValidSmartData
+		}
 	}
 
-	hasValidData := sm.parseScan(output)
+	finalDevices := mergeDeviceLists(scannedDevices, configuredDevices)
-	if !hasValidData {
+	sm.updateSmartDevices(finalDevices)
+	if len(finalDevices) == 0 {
+		if scanErr != nil {
+			return scanErr
+		}
 		return errNoValidSmartData
 	}
+
 	return nil
 }
 
-func (sm *SmartManager) parseConfiguredDevices(config string) error {
+func (sm *SmartManager) parseConfiguredDevices(config string) ([]*DeviceInfo, error) {
 	entries := strings.Split(config, ",")
 	devices := make([]*DeviceInfo, 0, len(entries))
 	for _, entry := range entries {
@@ -179,7 +197,7 @@ func (sm *SmartManager) parseConfiguredDevices(config string) error {
 
 		name := strings.TrimSpace(parts[0])
 		if name == "" {
-			return fmt.Errorf("invalid SMART_DEVICES entry %q: device name is required", entry)
+			return nil, fmt.Errorf("invalid SMART_DEVICES entry %q: device name is required", entry)
 		}
 
 		devType := ""
@@ -194,16 +212,10 @@ func (sm *SmartManager) parseConfiguredDevices(config string) error {
 	}
 
 	if len(devices) == 0 {
-		sm.Lock()
+		return nil, errNoValidSmartData
-		sm.SmartDevices = nil
-		sm.Unlock()
-		return errNoValidSmartData
 	}
 
-	sm.Lock()
+	return devices, nil
-	sm.SmartDevices = devices
-	sm.Unlock()
-	return nil
 }
 
 // detectDeviceType extracts the device type reported in smartctl JSON output.
@@ -345,12 +357,8 @@ func (sm *SmartManager) hasDataForDevice(deviceName string) bool {
 	return false
 }
 
-// parseScan parses the output of smartctl --scan -j and updates the SmartDevices slice
+// parseScan parses the output of smartctl --scan -j and returns the discovered devices.
-func (sm *SmartManager) parseScan(output []byte) bool {
+func (sm *SmartManager) parseScan(output []byte) ([]*DeviceInfo, bool) {
-	sm.Lock()
-	defer sm.Unlock()
-
-	sm.SmartDevices = make([]*DeviceInfo, 0)
 	scan := &scanOutput{}
 
 	if err := json.Unmarshal(output, scan); err != nil {
@@ -362,33 +370,97 @@ func (sm *SmartManager) parseScan(output []byte) bool {
 		return false
 	}
 
-	scannedDeviceNameMap := make(map[string]bool, len(scan.Devices))
+	devices := make([]*DeviceInfo, 0, len(scan.Devices))
-
 	for _, device := range scan.Devices {
-		deviceInfo := &DeviceInfo{
+		// slog.Info("found device during scan", "name", device.Name, "type", device.Type, "protocol", device.Protocol)
+		devices = append(devices, &DeviceInfo{
 			Name:     device.Name,
 			Type:     device.Type,
 			InfoName: device.InfoName,
 			Protocol: device.Protocol,
+		})
 	}
-		sm.SmartDevices = append(sm.SmartDevices, deviceInfo)
+
-		scannedDeviceNameMap[device.Name] = true
+	return devices, true
 }
-	// remove cached entries whose device path no longer appears in the scan
+
+// mergeDeviceLists combines scanned and configured SMART devices, preferring
+// configured SMART_DEVICES when both sources reference the same device.
+func mergeDeviceLists(scanned, configured []*DeviceInfo) []*DeviceInfo {
+	if len(scanned) == 0 && len(configured) == 0 {
+		return nil
+	}
+
+	finalDevices := make([]*DeviceInfo, 0, len(scanned)+len(configured))
+	deviceIndex := make(map[string]*DeviceInfo, len(scanned)+len(configured))
+
+	for _, dev := range scanned {
+		if dev == nil || dev.Name == "" {
+			continue
+		}
+		copyDev := *dev
+		finalDevices = append(finalDevices, &copyDev)
+		deviceIndex[copyDev.Name] = finalDevices[len(finalDevices)-1]
+	}
+
+	for _, dev := range configured {
+		if dev == nil || dev.Name == "" {
+			continue
+		}
+
+		if existing, ok := deviceIndex[dev.Name]; ok {
+			if dev.Type != "" {
+				existing.Type = dev.Type
+			}
+			if dev.InfoName != "" {
+				existing.InfoName = dev.InfoName
+			}
+			if dev.Protocol != "" {
+				existing.Protocol = dev.Protocol
+			}
+			continue
+		}
+
+		copyDev := *dev
+		finalDevices = append(finalDevices, &copyDev)
+		deviceIndex[copyDev.Name] = finalDevices[len(finalDevices)-1]
+	}
+
+	return finalDevices
+}
+
+// updateSmartDevices replaces the cached device list and prunes SMART data
+// entries whose backing device no longer exists.
+func (sm *SmartManager) updateSmartDevices(devices []*DeviceInfo) {
+	sm.Lock()
+	defer sm.Unlock()
+
+	sm.SmartDevices = devices
+
+	if len(sm.SmartDataMap) == 0 {
+		return
+	}
+
+	validNames := make(map[string]struct{}, len(devices))
+	for _, device := range devices {
+		if device == nil || device.Name == "" {
+			continue
+		}
+		validNames[device.Name] = struct{}{}
+	}
+
 	for key, data := range sm.SmartDataMap {
 		if data == nil {
 			delete(sm.SmartDataMap, key)
 continue
 		}
 
-		if _, ok := scannedDeviceNameMap[data.DiskName]; ok {
+		if _, ok := validNames[data.DiskName]; ok {
 			continue
 		}
 
 		delete(sm.SmartDataMap, key)
 	}
-
-	return true
 }
 
 // isVirtualDevice checks if a device is a virtual disk that should be filtered out

agent/smart_test.go

@@ -159,7 +159,7 @@ func TestScanDevicesWithEnvOverride(t *testing.T) {
 		SmartDataMap: make(map[string]*smart.SmartData),
 	}
 
-	err := sm.ScanDevices()
+	err := sm.ScanDevices(true)
 	require.NoError(t, err)
 
 	require.Len(t, sm.SmartDevices, 2)
@@ -176,7 +176,7 @@ func TestScanDevicesWithEnvOverrideInvalid(t *testing.T) {
 		SmartDataMap: make(map[string]*smart.SmartData),
 	}
 
-	err := sm.ScanDevices()
+	err := sm.ScanDevices(true)
 	require.Error(t, err)
 }
 
@@ -187,7 +187,7 @@ func TestScanDevicesWithEnvOverrideEmpty(t *testing.T) {
 		SmartDataMap: make(map[string]*smart.SmartData),
 	}
 
-	err := sm.ScanDevices()
+	err := sm.ScanDevices(true)
 	assert.ErrorIs(t, err, errNoValidSmartData)
 	assert.Empty(t, sm.SmartDevices)
 }
@@ -315,9 +315,11 @@ func TestParseScan(t *testing.T) {
         ]
     }`)
 
-	hasData := sm.parseScan(scanJSON)
+	devices, hasData := sm.parseScan(scanJSON)
 	assert.True(t, hasData)
 
+	sm.updateSmartDevices(devices)
+
 	require.Len(t, sm.SmartDevices, 2)
 	assert.Equal(t, "/dev/sda", sm.SmartDevices[0].Name)
 	assert.Equal(t, "sat", sm.SmartDevices[0].Type)
@@ -331,6 +333,36 @@ func TestParseScan(t *testing.T) {
 	assert.False(t, staleExists, "stale smart data entry should be removed when device path disappears")
 }
 
+func TestMergeDeviceListsPrefersConfigured(t *testing.T) {
+	scanned := []*DeviceInfo{
+		{Name: "/dev/sda", Type: "sat", InfoName: "scan-info", Protocol: "ATA"},
+		{Name: "/dev/nvme0", Type: "nvme"},
+	}
+
+	configured := []*DeviceInfo{
+		{Name: "/dev/sda", Type: "sat-override"},
+		{Name: "/dev/sdb", Type: "sat"},
+	}
+
+	merged := mergeDeviceLists(scanned, configured)
+	require.Len(t, merged, 3)
+
+	byName := make(map[string]*DeviceInfo, len(merged))
+	for _, dev := range merged {
+		byName[dev.Name] = dev
+	}
+
+	require.Contains(t, byName, "/dev/sda")
+	assert.Equal(t, "sat-override", byName["/dev/sda"].Type, "configured type should override scanned type")
+	assert.Equal(t, "scan-info", byName["/dev/sda"].InfoName, "scan metadata should be preserved when config does not provide it")
+
+	require.Contains(t, byName, "/dev/nvme0")
+	assert.Equal(t, "nvme", byName["/dev/nvme0"].Type)
+
+	require.Contains(t, byName, "/dev/sdb")
+	assert.Equal(t, "sat", byName["/dev/sdb"].Type)
+}
+
 func assertAttrValue(t *testing.T, attributes []*smart.SmartAttribute, name string, expected uint64) {
 	t.Helper()
 	attr := findAttr(attributes, name)