os: add system installation date to metrics (#2284)

Co-authored-by: EisenbergD <dominik.eisenberg@beiersdorf.com>

docs/collector.os.md

@@ -14,10 +14,11 @@ None
 
 ## Metrics
 
-| Name                  | Description                                                                                                                                                    | Type  | Labels                                                                 |
+| Name                                 | Description                                                                                                                                                    | Type  | Labels                                                                                                          |
-|-----------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------|-------|------------------------------------------------------------------------|
+|--------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------|-------|-----------------------------------------------------------------------------------------------------------------|
-| `windows_os_hostname` | Labelled system hostname information as provided by ComputerSystem.DNSHostName and ComputerSystem.Domain                                                       | gauge | `domain`, `fqdn`, `hostname`                                           |
+| `windows_os_hostname`                | Labelled system hostname information as provided by ComputerSystem.DNSHostName and ComputerSystem.Domain                                                       | gauge | `domain`, `fqdn`, `hostname`                                                                                    |
-| `windows_os_info`     | Contains full product name & version in labels. Note that the `major_version` for Windows 11 is "10"; a build number greater than 22000 represents Windows 11. | gauge | `product`, `version`, `major_version`, `minor_version`, `build_number`, `installation_type`|
+| `windows_os_info`                    | Contains full product name & version in labels. Note that the `major_version` for Windows 11 is "10"; a build number greater than 22000 represents Windows 11. | gauge | `product`, `version`, `major_version`, `minor_version`, `build_number`, `revision`, `installation_type`         |
+| `windows_os_install_time_timestamp`  | Unix timestamp of OS installation time                                                                                                                         | gauge | None                                                                                                            |
 
 ### Example metric
 
@@ -27,7 +28,10 @@ None
 windows_os_hostname{domain="",fqdn="PC",hostname="PC"} 1
 # HELP windows_os_info Contains full product name & version in labels. Note that the "major_version" for Windows 11 is \\"10\\"; a build number greater than 22000 represents Windows 11.
 # TYPE windows_os_info gauge
-windows_os_info{build_number="19045",major_version="10",minor_version="0",product="Windows 10 Pro",revision="4842",version="10.0.19045"} 1
+windows_os_info{build_number="19045",installation_type="Client",major_version="10",minor_version="0",product="Windows 10 Pro",revision="4842",version="10.0.19045"} 1
+# HELP windows_os_install_time_timestamp Unix timestamp of OS installation time
+# TYPE windows_os_install_time_timestamp gauge
+windows_os_install_time_timestamp 1.6725312e+09
 ```
 
 ## Useful queries

internal/collector/os/os.go

@@ -44,8 +44,11 @@ var ConfigDefaults = Config{}
 type Collector struct {
 	config Config
 
+	installTimeTimestamp float64
+
 	hostname      *prometheus.Desc
 	osInformation *prometheus.Desc
+	installTime   *prometheus.Desc
 }
 
 func New(config *Config) *Collector {
@@ -78,6 +81,13 @@ func (c *Collector) Build(_ *slog.Logger, _ *mi.Session) error {
 		return fmt.Errorf("failed to get Windows version: %w", err)
 	}
 
+	installTimeTimestamp, err := c.getInstallTime()
+	if err != nil {
+		return fmt.Errorf("failed to get install time: %w", err)
+	}
+
+	c.installTimeTimestamp = installTimeTimestamp
+
 	version := osversion.Get()
 
 	// Microsoft has decided to keep the major version as "10" for Windows 11, including the product name.
@@ -111,6 +121,13 @@ func (c *Collector) Build(_ *slog.Logger, _ *mi.Session) error {
 		nil,
 	)
 
+	c.installTime = prometheus.NewDesc(
+		prometheus.BuildFQName(types.Namespace, Name, "install_time_timestamp"),
+		"Unix timestamp of OS installation time",
+		nil,
+		nil,
+	)
+
 	return nil
 }
 
@@ -125,6 +142,12 @@ func (c *Collector) Collect(ch chan<- prometheus.Metric) error {
 		1.0,
 	)
 
+	ch <- prometheus.MustNewConstMetric(
+		c.installTime,
+		prometheus.GaugeValue,
+		c.installTimeTimestamp,
+	)
+
 	if err := c.collectHostname(ch); err != nil {
 		errs = append(errs, fmt.Errorf("failed to collect hostname metrics: %w", err))
 	}
@@ -190,3 +213,23 @@ func (c *Collector) getWindowsVersion() (string, string, string, error) {
 
 	return strings.TrimSpace(productName), strconv.FormatUint(revision, 10), strings.TrimSpace(installationType), nil
 }
+
+func (c *Collector) getInstallTime() (float64, error) {
+	ntKey, err := registry.OpenKey(registry.LOCAL_MACHINE, `SOFTWARE\Microsoft\Windows NT\CurrentVersion`, registry.QUERY_VALUE)
+	if err != nil {
+		return 0, fmt.Errorf("failed to open registry key: %w", err)
+	}
+
+	defer func(ntKey registry.Key) {
+		_ = ntKey.Close()
+	}(ntKey)
+
+	installDate, _, err := ntKey.GetIntegerValue("InstallDate")
+	if errors.Is(err, registry.ErrNotExist) {
+		return 0, nil
+	} else if err != nil {
+		return 0, err
+	}
+
+	return float64(installDate), nil
+}

tools/e2e-output.txt

@@ -287,6 +287,8 @@ windows_exporter_collector_timeout{collector="udp"} 0
 # TYPE windows_os_hostname gauge
 # HELP windows_os_info Contains full product name & version in labels. Note that the "major_version" for Windows 11 is \\"10\\"; a build number greater than 22000 represents Windows 11.
 # TYPE windows_os_info gauge
+# HELP windows_os_install_time_timestamp Unix timestamp of OS installation time
+# TYPE windows_os_install_time_timestamp gauge
 # HELP windows_pagefile_free_bytes Number of bytes that can be mapped into the operating system paging files without causing any other pages to be swapped out
 # TYPE windows_pagefile_free_bytes gauge
 # HELP windows_pagefile_limit_bytes Number of bytes that can be stored in the operating system paging files. 0 (zero) indicates that there are no paging files