check_drivesize: fix drives without assigned letters

docs/checks/commands/check_drivesize.md

@@ -92,6 +92,7 @@ these can be used in filters and thresholds (along with the default attributes):
 | id                    | Drive or id of drive                                                                          |
 | drive_or_id           | Drive letter if present if not use id                                                         |
 | drive_or_name         | Drive letter if present if not use name                                                       |
+| drive_or_name_or_id   | Drive letter if present, if not use drive name, if not use the given ID. Useful for volumes without assigned letters on Windows. |
 | fstype                | Filesystem type                                                                               |
 | mounted               | Flag whether drive is mounter (0/1)                                                           |
 | free                  | Free (human readable) bytes                                                                   |

pkg/snclient/check_drivesize.go

@@ -113,6 +113,7 @@ func (l *CheckDrivesize) Build() *CheckData {
 			{name: "id", description: "Drive or id of drive"},
 			{name: "drive_or_id", description: "Drive letter if present if not use id"},
 			{name: "drive_or_name", description: "Drive letter if present if not use name"},
+			{name: "drive_or_name_or_id", description: "Drive letter if present, if not use drive name, if not use the given ID. Useful for volumes without assigned letters on Windows."},
 			{name: "fstype", description: "Filesystem type"},
 			{name: "mounted", description: "Flag whether drive is mounter (0/1)", unit: UBool},
 
@@ -298,7 +299,7 @@ func (l *CheckDrivesize) isExcluded(drive map[string]string, excludes []string)
 	return false
 }
 
-func (l *CheckDrivesize) addMetrics(drive string, check *CheckData, usage *disk.UsageStat, magic float64) {
+func (l *CheckDrivesize) addMetrics(metricPrefix string, check *CheckData, usage *disk.UsageStat, magic float64) {
 	total := usage.Total
 	if !l.freespaceIgnoreReserved {
 		total = usage.Used + usage.Free // use this total instead of usage.Total to account in the root reserved space
@@ -307,34 +308,34 @@ func (l *CheckDrivesize) addMetrics(drive string, check *CheckData, usage *disk.
 	if check.HasThreshold("free") || check.HasThreshold("free_pct") || check.HasThreshold("free_bytes") {
 		check.warnThreshold = check.TransformMultipleKeywords([]string{"free_pct", "free_bytes"}, "free", check.warnThreshold)
 		check.critThreshold = check.TransformMultipleKeywords([]string{"free_pct", "free_bytes"}, "free", check.critThreshold)
-		check.AddBytePercentMetrics("free", drive+" free", magic*float64(usage.Free), magic*float64(total))
+		check.AddBytePercentMetrics("free", metricPrefix+" free", magic*float64(usage.Free), magic*float64(total))
 	}
 
 	// convert '<drive> used_pct' keywords in conditions to '<drive> used %' as that matches the metric name
-	convertDriveUsagePctMetric1 := fmt.Sprintf("%s used_pct", drive)
+	convertDriveUsagePctMetric1 := fmt.Sprintf("%s used_pct", metricPrefix)
 	// metrics are normally added if the operand is simply 'used' , 'used_pct' , 'used_bytes' etc. and do not have a drive prefix
 	// detect conditions where the operand is named '<drive> used %', this is the default way snclient names percent usage metrics.
 	// if there is a condition using that as an operand, add usage metrics for that drive as well. during the metrics condition checking, they will take effect.
 	// this helps to check usage metrics specific to drives.
-	driveUsagePctMetric := fmt.Sprintf("%s used %%", drive)
+	driveUsagePctMetric := fmt.Sprintf("%s used %%", metricPrefix)
 
 	check.warnThreshold = check.TransformMultipleKeywords([]string{convertDriveUsagePctMetric1}, driveUsagePctMetric, check.warnThreshold)
 	check.critThreshold = check.TransformMultipleKeywords([]string{convertDriveUsagePctMetric1}, driveUsagePctMetric, check.critThreshold)
 
 	if check.HasThreshold(driveUsagePctMetric) || check.HasThreshold("used") || check.HasThreshold("used_pct") || check.HasThreshold("used_bytes") {
 		check.warnThreshold = check.TransformMultipleKeywords([]string{"used_pct", "used_bytes"}, "used", check.warnThreshold)
 		check.critThreshold = check.TransformMultipleKeywords([]string{"used_pct", "used_bytes"}, "used", check.critThreshold)
-		check.AddBytePercentMetrics("used", drive+" used", magic*float64(usage.Used), magic*float64(total))
+		check.AddBytePercentMetrics("used", metricPrefix+" used", magic*float64(usage.Used), magic*float64(total))
 	}
 	if check.HasThreshold("inodes") || check.HasThreshold("inodes_used") || check.HasThreshold("inodes_used_pct") {
 		check.warnThreshold = check.TransformMultipleKeywords([]string{"inodes_used_pct", "inodes_used"}, "inodes", check.warnThreshold)
 		check.critThreshold = check.TransformMultipleKeywords([]string{"inodes_used_pct", "inodes_used"}, "inodes", check.critThreshold)
-		check.AddPercentMetrics("inodes", drive+" inodes", float64(usage.InodesUsed), float64(usage.InodesTotal))
+		check.AddPercentMetrics("inodes", metricPrefix+" inodes", float64(usage.InodesUsed), float64(usage.InodesTotal))
 	}
 	if check.HasThreshold("inodes_free") || check.HasThreshold("inodes_free_pct") {
 		check.warnThreshold = check.TransformMultipleKeywords([]string{"inodes_free_pct"}, "inodes_free", check.warnThreshold)
 		check.critThreshold = check.TransformMultipleKeywords([]string{"inodes_free_pct"}, "inodes_free", check.critThreshold)
-		check.AddPercentMetrics("inodes_free", drive+" inodes free", float64(usage.InodesFree), float64(usage.InodesTotal))
+		check.AddPercentMetrics("inodes_free", metricPrefix+" inodes free", float64(usage.InodesFree), float64(usage.InodesTotal))
 	}
 }
 
@@ -452,7 +453,9 @@ func (l *CheckDrivesize) addDriveSizeDetails(check *CheckData, drive map[string]
 		return
 	}
 
-	l.addMetrics(drive["drive"], check, usage, magic)
+	// volumes without an assigned drive letter have empty drive["drive"]
+	// use the volume name or id as fallback
+	l.addMetrics(drive["drive_or_name_or_id"], check, usage, magic)
 }
 
 func (l *CheckDrivesize) getFlagNames(drive map[string]string) []string {

pkg/snclient/check_drivesize_other.go

@@ -81,6 +81,7 @@ func (l *CheckDrivesize) setDisks(requiredDisks map[string]map[string]string) (e
 		entry["drive"] = drive
 		entry["drive_or_id"] = drive
 		entry["drive_or_name"] = drive
+		entry["drive_or_name_or_id"] = drive
 		entry["fstype"] = partition.Fstype
 		requiredDisks[drive] = entry
 	}

pkg/snclient/check_drivesize_windows.go

@@ -325,10 +325,24 @@ func (l *CheckDrivesize) setDeviceInfo(drive map[string]string) {
 	}
 
 	name := syscall.UTF16ToString(volumeName)
+	drive["name"] = name
+
 	driveOrName := drive["drive"]
 	if driveOrName == "" {
 		driveOrName = name
 	}
+	if drive["drive_or_name"] == "" {
+		drive["drive_or_name"] = driveOrName
+	}
+
+	driveOrNameOrID := driveOrName
+	if driveOrNameOrID == "" {
+		driveOrNameOrID = drive["drive_or_id"]
+	}
+	if drive["drive_or_name_or_id"] == "" {
+		drive["drive_or_name_or_id"] = driveOrNameOrID
+	}
+
 	drive["readable"] = "1"
 	if fileSystemFlags&volumeOptReadOnly == 0 {
 		drive["writable"] = "1"
@@ -339,15 +353,11 @@ func (l *CheckDrivesize) setDeviceInfo(drive map[string]string) {
 	if fileSystemFlags&volumeCompressed == 0 {
 		opts = append(opts, "compress")
 	}
-
 	drive["opts"] = strings.Join(opts, ",")
-	drive["name"] = name
+
 	if drive["fstype"] == "" {
 		drive["fstype"] = syscall.UTF16ToString(fileSystemName)
 	}
-	if drive["drive_or_name"] == "" {
-		drive["drive_or_name"] = driveOrName
-	}
 }
 
 // gopsutil disk.Partition had an issue with Bitlocker, but a fix was upstreamed