Add a cpu_info collector

The cpu_info collector exposes a single metric per socket with some
information on installed CPUs, somewhat like the node_cpu_info metric

Signed-off-by: Steffen Higel <higels@valvesoftware.com>

README.md

@@ -12,6 +12,7 @@ Name     | Description | Enabled by default
 [ad](docs/collector.ad.md) | Active Directory Domain Services |
 [adfs](docs/collector.adfs.md) | Active Directory Federation Services |
 [cpu](docs/collector.cpu.md) | CPU usage | ✓
+[cpu_info](docs/collector.cpu_info.md) | CPU Information |
 [cs](docs/collector.cs.md) | "Computer System" metrics (system properties, num cpus/total memory) | ✓
 [container](docs/collector.container.md) | Container metrics |
 [dfsr](docs/collector.dfsr.md) | DFSR metrics |

collector/cpu_info.go

@@ -0,0 +1,96 @@
+// +build windows
+
+package collector
+
+import (
+	"errors"
+	"strconv"
+	"strings"
+
+	"github.com/StackExchange/wmi"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/common/log"
+)
+
+func init() {
+	registerCollector("cpu_info", newCpuInfoCollector)
+}
+
+// If you are adding additional labels to the metric, make sure that they get added in here as well. See below for explanation.
+const (
+	win32ProcessorQuery = "SELECT Architecture, DeviceId, Description, Family, L2CacheSize, L3CacheSize, Name FROM Win32_Processor"
+)
+
+// A CpuInfoCollector is a Prometheus collector for a few WMI metrics in Win32_Processor
+type CpuInfoCollector struct {
+	CpuInfo *prometheus.Desc
+}
+
+func newCpuInfoCollector() (Collector, error) {
+	return &CpuInfoCollector{
+		CpuInfo: prometheus.NewDesc(
+			prometheus.BuildFQName(Namespace, "", "cpu_info"),
+			"Labeled CPU information as provided provided by Win32_Processor",
+			[]string{
+				"architecture",
+				"device_id",
+				"description",
+				"family",
+				"l2_cache_size",
+				"l3_cache_size",
+				"name"},
+			nil,
+		),
+	}, nil
+}
+
+type win32_Processor struct {
+	Architecture uint32
+	DeviceID     string
+	Description  string
+	Family       uint16
+	L2CacheSize  uint32
+	L3CacheSize  uint32
+	Name         string
+}
+
+// Collect sends the metric values for each metric
+// to the provided prometheus Metric channel.
+func (c *CpuInfoCollector) Collect(ctx *ScrapeContext, ch chan<- prometheus.Metric) error {
+	if desc, err := c.collect(ch); err != nil {
+		log.Error("failed collecting cpu_info metrics:", desc, err)
+		return err
+	}
+	return nil
+}
+
+func (c *CpuInfoCollector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, error) {
+	var dst []win32_Processor
+	// We use a static query here because the provided methods in wmi.go all issue a SELECT *;
+	// This results in the time consuming LoadPercentage field being read which seems to measure each CPU
+	// serially over a 1 second interval, so the scrape time is at least 1s * num_sockets
+	if err := wmi.Query(win32ProcessorQuery, &dst); err != nil {
+		return nil, err
+	}
+	if len(dst) == 0 {
+		return nil, errors.New("WMI query returned empty result set")
+	}
+
+	// Some CPUs end up exposing trailing spaces for certain strings, so clean them up
+	for _, processor := range dst {
+		ch <- prometheus.MustNewConstMetric(
+			c.CpuInfo,
+			prometheus.GaugeValue,
+			1.0,
+			strconv.Itoa(int(processor.Architecture)),
+			strings.TrimRight(processor.DeviceID, " "),
+			strings.TrimRight(processor.Description, " "),
+			strconv.Itoa(int(processor.Family)),
+			strconv.Itoa(int(processor.L2CacheSize)),
+			strconv.Itoa(int(processor.L3CacheSize)),
+			strings.TrimRight(processor.Name, " "),
+		)
+	}
+
+	return nil, nil
+}

docs/collector.cpu_info.md

@@ -0,0 +1,31 @@
+# cpu_info collector
+
+The cpu_info collector exposes metrics detailing a per-socket breakdown of the Processors in the system
+
+|||
+-|-
+Metric name prefix  | `cpu_info`
+Classes             | [`Win32_Processor`](https://docs.microsoft.com/en-us/windows/win32/cimwin32prov/win32-processor)
+Enabled by default? | No
+
+## Flags
+
+None
+
+## Metrics
+
+Name | Description | Type | Labels
+-----|-------------|------|-------
+`windows_cpu_info` | Labeled CPU information | gauge | `architecture`, `device_id`, `description`, `family`, `l2_cache_size` `l3_cache_size`, `name`
+
+### Example metric
+```
+windows_cpu_info{architecture="9",description="AMD64 Family 23 Model 49 Stepping 0",device_id="CPU0",family="107",l2_cache_size="32768",l3_cache_size="262144",name="AMD EPYC 7702P 64-Core Processor"} 1
+```
+The value of the metric is irrelevant, but the labels expose some useful information on the CPU installed in each socket.
+
+## Useful queries
+_This collector does not yet have any useful queries added, we would appreciate your help adding them!_
+
+## Alerting examples
+_This collector does not yet have alerting examples, we would appreciate your help adding them!_