Add support for autoscan device types and predictable device paths

This adds a new command line option allowing for customization of
autodetected device types and enables use of special "by-id" device type
that forces use of predictable device paths (/dev/disk/by-id/...)

Relevant change to device name parsing regular expression is included
now, so predictable device paths are now also usable when directly
specified.

Signed-off-by: Piotr Dobrowolski <[email protected]>

main.go

@@ -108,6 +108,10 @@ var (
 		"smartctl.device-include",
 		"Regexp of devices to exclude from automatic scanning. (mutually exclusive to device-exclude)",
 	).Default("").String()
+	smartctlDeviceTypes = kingpin.Flag(
+		"smartctl.device-type",
+		"Device type to use during automatic scan. Special by-id value forces predictable device names. (repeatable)",
+	).Strings()
 	smartctlFakeData = kingpin.Flag("smartctl.fake-data",
 		"The device to monitor (repeatable)",
 	).Default("false").Hidden().Bool()

readjson.go

@@ -77,7 +77,11 @@ func readSMARTctl(logger log.Logger, device Device) (gjson.Result, bool) {
 
 func readSMARTctlDevices(logger log.Logger) gjson.Result {
 	level.Debug(logger).Log("msg", "Scanning for devices")
-	out, err := exec.Command(*smartctlPath, "--json", "--scan").Output()
+	var scanArgs []string = []string{"--json", "--scan"}
+	for _, d := range *smartctlDeviceTypes {
+		scanArgs = append(scanArgs, "--device", d)
+	}
+	out, err := exec.Command(*smartctlPath, scanArgs...).Output()
 	if exiterr, ok := err.(*exec.ExitError); ok {
 		level.Debug(logger).Log("msg", "Exit Status", "exit_code", exiterr.ExitCode())
 		// The smartctl command returns 2 if devices are sleeping, ignore this error.

smartctl.go

@@ -44,7 +44,7 @@ type SMARTctl struct {
 }
 
 func extractDiskName(input string) string {
-	re := regexp.MustCompile(`^(?:/dev/(?P<bus_name>\S+)/(?P<bus_num>\S+)\s\[|/dev/|\[)(?:\s\[|)(?P<disk>[a-z0-9_]+)(?:\].*|)$`)
+	re := regexp.MustCompile(`^(?:/dev/(?P<bus_name>\S+)/(?P<bus_num>\S+)\s\[|/dev/(?:disk\/by-id\/|disk\/by-path\/|)|\[)(?:\s\[|)(?P<disk>[A-Za-z0-9_\-]+)(?:\].*|)$`)
 	match := re.FindStringSubmatch(input)
 
 	if len(match) > 0 {