feat: add SystemdVirtualization type (#3254)

* feat: add SystemdVirtualization type
---------

Signed-off-by: IbraAoad <Ibrahim.Awwad@canonical.com>
Signed-off-by: Ibrahim Awwad <ibraaoad@gmail.com>
Signed-off-by: Mikel Olasagasti Uranga <mikel@olasagasti.info>
Signed-off-by: Alexander Soelberg Heidarsson <89837986+alex5517@users.noreply.github.com>
Co-authored-by: Ben Kochie <superq@gmail.com>
Co-authored-by: Mikel Olasagasti Uranga <mikel@olasagasti.info>
Co-authored-by: Alexander Soelberg Heidarsson <89837986+alex5517@users.noreply.github.com>

collector/systemd_linux.go

@@ -74,6 +74,7 @@ type systemdCollector struct {
 	socketCurrentConnectionsDesc  *prometheus.Desc
 	socketRefusedConnectionsDesc  *prometheus.Desc
 	systemdVersionDesc            *prometheus.Desc
+	virtualizationDesc            *prometheus.Desc
 	// Use regexps for more flexibility than device_filter.go allows
 	systemdUnitIncludePattern *regexp.Regexp
 	systemdUnitExcludePattern *regexp.Regexp
@@ -132,6 +133,9 @@ func NewSystemdCollector(logger *slog.Logger) (Collector, error) {
 	systemdVersionDesc := prometheus.NewDesc(
 		prometheus.BuildFQName(namespace, subsystem, "version"),
 		"Detected systemd version", []string{"version"}, nil)
+	virtualizationDesc := prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, subsystem, "virtualization_info"),
+		"Detected virtualization technology", []string{"virtualization_type"}, nil)
 
 	if *oldSystemdUnitExclude != "" {
 		if !systemdUnitExcludeSet {
@@ -167,6 +171,7 @@ func NewSystemdCollector(logger *slog.Logger) (Collector, error) {
 		socketCurrentConnectionsDesc:  socketCurrentConnectionsDesc,
 		socketRefusedConnectionsDesc:  socketRefusedConnectionsDesc,
 		systemdVersionDesc:            systemdVersionDesc,
+		virtualizationDesc:            virtualizationDesc,
 		systemdUnitIncludePattern:     systemdUnitIncludePattern,
 		systemdUnitExcludePattern:     systemdUnitExcludePattern,
 		logger:                        logger,
@@ -194,6 +199,14 @@ func (c *systemdCollector) Update(ch chan<- prometheus.Metric) error {
 		systemdVersionFull,
 	)
 
+	systemdVirtualization := c.getSystemdVirtualization(conn)
+	ch <- prometheus.MustNewConstMetric(
+		c.virtualizationDesc,
+		prometheus.GaugeValue,
+		1.0,
+		systemdVirtualization,
+	)
+
 	allUnits, err := c.getAllUnits(conn)
 	if err != nil {
 		return fmt.Errorf("couldn't get units: %w", err)
@@ -505,3 +518,19 @@ func (c *systemdCollector) getSystemdVersion(conn *dbus.Conn) (float64, string)
 	}
 	return v, version
 }
+
+func (c *systemdCollector) getSystemdVirtualization(conn *dbus.Conn) string {
+	virt, err := conn.GetManagerProperty("Virtualization")
+	if err != nil {
+		c.logger.Debug("Could not get Virtualization property", "err", err)
+		return "unknown"
+	}
+
+	virtStr := strings.Trim(virt, `"`)
+	if virtStr == "" {
+		// If no virtualization type is returned, assume it's bare metal.
+		return "none"
+	}
+
+	return virtStr
+}