feat: Support OpenMetrics (#1772)

Signed-off-by: Jan-Otto Kröpke <mail@jkroepke.de>

.run/all.run.xml

@@ -2,7 +2,7 @@
   <configuration default="false" name="all" type="GoApplicationRunConfiguration" factoryName="Go Application" folderName="run">
     <module name="windows_exporter" />
     <working_directory value="$PROJECT_DIR$" />
-    <parameters value="--web.listen-address=127.0.0.1:9182 --log.level=debug --collectors.enabled=ad,adcs,adfs,cache,container,cpu,cpu_info,cs,dfsr,dhcp,diskdrive,dns,exchange,filetime,fsrmquota,hyperv,iis,license,logical_disk,logon,memory,mscluster,msmq,mssql,net,netframework,nps,os,pagefile,perfdata,physical_disk,printer,process,remote_fx,scheduled_task,service,smb,smbclient,smtp,system,tcp,terminal_services,textfile,thermalzone,time,udp,update,vmware" />
+    <parameters value="--web.listen-address=127.0.0.1:9182 --log.level=info --collectors.enabled=ad,adcs,adfs,cache,container,cpu,cpu_info,cs,dfsr,dhcp,diskdrive,dns,exchange,filetime,fsrmquota,hyperv,iis,license,logical_disk,logon,memory,mscluster,msmq,mssql,net,netframework,nps,os,pagefile,perfdata,physical_disk,printer,process,remote_fx,scheduled_task,service,smb,smbclient,smtp,system,tcp,terminal_services,thermalzone,time,udp,update,vmware --debug.enabled" />
     <sudo value="true" />
     <kind value="PACKAGE" />
     <package value="github.com/prometheus-community/windows_exporter/cmd/windows_exporter" />

README.md

@@ -199,6 +199,14 @@ Windows Server 2012 and 2012R2 are supported as best-effort only, but not guaran
 
 The prometheus metrics will be exposed on [localhost:9182](http://localhost:9182)
 
+### HTTP Endpoints
+
+windows_exporter provides the following HTTP endpoints:
+
+* `/metrics`: Exposes metrics in the [Prometheus text format](https://prometheus.io/docs/instrumenting/exposition_formats/).
+* `/health`: Returns 200 OK when the exporter is running.
+* `/debug/pprof/`: Exposes the [pprof](https://golang.org/pkg/net/http/pprof/) endpoints. Only, if `--debug.enabled` is set.
+
 ## Examples
 
 ### Enable only service collector and specify a custom query

cmd/windows_exporter/main.go

@@ -87,10 +87,6 @@ func run() int {
 			"web.disable-exporter-metrics",
 			"Exclude metrics about the exporter itself (promhttp_*, process_*, go_*).",
 		).Bool()
-		maxRequests = app.Flag(
-			"telemetry.max-requests",
-			"Maximum number of concurrent requests. 0 to disable.",
-		).Default("5").Int()
 		enabledCollectors = app.Flag(
 			"collectors.enabled",
 			"Comma-separated list of collectors to use. Use '[defaults]' as a placeholder for all the collectors enabled by default.").
@@ -220,7 +216,6 @@ func run() int {
 	mux.Handle("GET "+*metricsPath, httphandler.New(logger, collectors, &httphandler.Options{
 		DisableExporterMetrics: *disableExporterMetrics,
 		TimeoutMargin:          *timeoutMargin,
-		MaxRequests:            *maxRequests,
 	}))
 
 	if *debugEnabled {

internal/httphandler/httphandler.go

@@ -49,7 +49,6 @@ type MetricsHTTPHandler struct {
 type Options struct {
 	DisableExporterMetrics bool
 	TimeoutMargin          float64
-	MaxRequests            int
 }
 
 func New(logger *slog.Logger, metricCollectors *collector.MetricCollectors, options *Options) *MetricsHTTPHandler {
@@ -57,7 +56,6 @@ func New(logger *slog.Logger, metricCollectors *collector.MetricCollectors, opti
 		options = &Options{
 			DisableExporterMetrics: false,
 			TimeoutMargin:          0.5,
-			MaxRequests:            5,
 		}
 	}
 
@@ -65,7 +63,9 @@ func New(logger *slog.Logger, metricCollectors *collector.MetricCollectors, opti
 		metricCollectors: metricCollectors,
 		logger:           logger,
 		options:          *options,
-		concurrencyCh:    make(chan struct{}, options.MaxRequests),
+
+		// We are expose metrics directly from the memory region of the Win32 API. We should not allow more than one request at a time.
+		concurrencyCh: make(chan struct{}, 1),
 	}
 
 	if !options.DisableExporterMetrics {
@@ -131,21 +131,11 @@ func (c *MetricsHTTPHandler) handlerFactory(logger *slog.Logger, scrapeTimeout t
 	if len(requestedCollectors) == 0 {
 		metricCollectors = c.metricCollectors
 	} else {
-		filteredCollectors := make(collector.Map)
+		var err error
 
-		for _, name := range requestedCollectors {
-			metricCollector, ok := c.metricCollectors.Collectors[name]
-			if !ok {
-				return nil, fmt.Errorf("couldn't find collector %s", name)
-			}
-
-			filteredCollectors[name] = metricCollector
-		}
-
-		metricCollectors = &collector.MetricCollectors{
-			Collectors:       filteredCollectors,
-			MISession:        c.metricCollectors.MISession,
-			PerfCounterQuery: c.metricCollectors.PerfCounterQuery,
+		metricCollectors, err = c.metricCollectors.CloneWithCollectors(requestedCollectors)
+		if err != nil {
+			return nil, fmt.Errorf("couldn't clone metric collectors: %w", err)
 		}
 	}
 
@@ -162,8 +152,10 @@ func (c *MetricsHTTPHandler) handlerFactory(logger *slog.Logger, scrapeTimeout t
 			promhttp.HandlerOpts{
 				ErrorLog:            slog.NewLogLogger(logger.Handler(), slog.LevelError),
 				ErrorHandling:       promhttp.ContinueOnError,
-				MaxRequestsInFlight: c.options.MaxRequests,
+				MaxRequestsInFlight: 1,
 				Registry:            c.exporterMetricsRegistry,
+				EnableOpenMetrics:   true,
+				ProcessStartTime:    c.metricCollectors.GetStartTime(),
 			},
 		)
 
@@ -178,7 +170,9 @@ func (c *MetricsHTTPHandler) handlerFactory(logger *slog.Logger, scrapeTimeout t
 			promhttp.HandlerOpts{
 				ErrorLog:            slog.NewLogLogger(logger.Handler(), slog.LevelError),
 				ErrorHandling:       promhttp.ContinueOnError,
-				MaxRequestsInFlight: c.options.MaxRequests,
+				MaxRequestsInFlight: 1,
+				EnableOpenMetrics:   true,
+				ProcessStartTime:    c.metricCollectors.GetStartTime(),
 			},
 		)
 	}
@@ -187,10 +181,6 @@ func (c *MetricsHTTPHandler) handlerFactory(logger *slog.Logger, scrapeTimeout t
 }
 
 func (c *MetricsHTTPHandler) withConcurrencyLimit(next http.HandlerFunc) http.HandlerFunc {
-	if c.options.MaxRequests <= 0 {
-		return next
-	}
-
 	return func(w http.ResponseWriter, r *http.Request) {
 		select {
 		case c.concurrencyCh <- struct{}{}:

internal/perfdata/collector.go

@@ -193,6 +193,13 @@ func (c *Collector) Collect() (CounterValues, error) {
 }
 
 func (c *Collector) collectRoutine() {
+	var (
+		itemCount   uint32
+		bytesNeeded uint32
+	)
+
+	buf := make([]byte, 1)
+
 	for range c.collectCh {
 		if ret := PdhCollectQueryData(c.handle); ret != ErrorSuccess {
 			c.counterValuesCh <- nil
@@ -207,25 +214,24 @@ func (c *Collector) collectRoutine() {
 			for _, counter := range c.counters {
 				for _, instance := range counter.Instances {
 					// Get the info with the current buffer size
-					var itemCount uint32
+					bytesNeeded = uint32(cap(buf))
 
-					// Get the info with the current buffer size
-					bufLen := uint32(0)
+					for {
+						ret := PdhGetRawCounterArray(instance, &bytesNeeded, &itemCount, &buf[0])
 
-					ret := PdhGetRawCounterArray(instance, &bufLen, &itemCount, nil)
-					if ret != PdhMoreData {
-						return nil, fmt.Errorf("PdhGetRawCounterArray: %w", NewPdhError(ret))
-					}
+						if ret == ErrorSuccess {
+							break
+						}
 
-					buf := make([]byte, bufLen)
-
-					ret = PdhGetRawCounterArray(instance, &bufLen, &itemCount, &buf[0])
-					if ret != ErrorSuccess {
-						if err := NewPdhError(ret); !isKnownCounterDataError(err) {
+						if err := NewPdhError(ret); ret != PdhMoreData && !isKnownCounterDataError(err) {
 							return nil, fmt.Errorf("PdhGetRawCounterArray: %w", err)
 						}
 
-						continue
+						if bytesNeeded <= uint32(cap(buf)) {
+							return nil, fmt.Errorf("PdhGetRawCounterArray reports buffer too small (%d), but buffer is large enough (%d): %w", uint32(cap(buf)), bytesNeeded, NewPdhError(ret))
+						}
+
+						buf = make([]byte, bytesNeeded)
 					}
 
 					items := unsafe.Slice((*PdhRawCounterItem)(unsafe.Pointer(&buf[0])), itemCount)

internal/perfdata/collector_bench_test.go

@@ -61,4 +61,6 @@ func BenchmarkTestCollector(b *testing.B) {
 	}
 
 	performanceData.Close()
+
+	b.ReportAllocs()
 }

pkg/collector/collector.go

@@ -19,8 +19,10 @@ import (
 	"errors"
 	"fmt"
 	"log/slog"
+	"maps"
 	"slices"
 	"sync"
+	stdtime "time"
 
 	"github.com/alecthomas/kingpin/v2"
 	"github.com/prometheus-community/windows_exporter/internal/collector/ad"
@@ -145,21 +147,21 @@ func NewWithConfig(config Config) *MetricCollectors {
 // New To be called by the external libraries for collector initialization.
 func New(collectors Map) *MetricCollectors {
 	return &MetricCollectors{
-		Collectors: collectors,
+		collectors: collectors,
 	}
 }
 
 // Enable removes all collectors that not enabledCollectors.
 func (c *MetricCollectors) Enable(enabledCollectors []string) error {
 	for _, name := range enabledCollectors {
-		if _, ok := c.Collectors[name]; !ok {
+		if _, ok := c.collectors[name]; !ok {
 			return fmt.Errorf("unknown collector %s", name)
 		}
 	}
 
-	for name := range c.Collectors {
+	for name := range c.collectors {
 		if !slices.Contains(enabledCollectors, name) {
-			delete(c.Collectors, name)
+			delete(c.collectors, name)
 		}
 	}
 
@@ -168,22 +170,24 @@ func (c *MetricCollectors) Enable(enabledCollectors []string) error {
 
 // Build To be called by the exporter for collector initialization.
 func (c *MetricCollectors) Build(logger *slog.Logger) error {
+	c.startTime = stdtime.Now()
+
 	err := c.initMI()
 	if err != nil {
 		return fmt.Errorf("error from initialize MI: %w", err)
 	}
 
 	wg := sync.WaitGroup{}
-	wg.Add(len(c.Collectors))
+	wg.Add(len(c.collectors))
 
-	errCh := make(chan error, len(c.Collectors))
-	errs := make([]error, 0, len(c.Collectors))
+	errCh := make(chan error, len(c.collectors))
+	errs := make([]error, 0, len(c.collectors))
 
-	for _, collector := range c.Collectors {
+	for _, collector := range c.collectors {
 		go func() {
 			defer wg.Done()
 
-			if err = collector.Build(logger, c.MISession); err != nil {
+			if err = collector.Build(logger, c.miSession); err != nil {
 				errCh <- fmt.Errorf("error build collector %s: %w", collector.GetName(), err)
 			}
 		}()
@@ -202,20 +206,20 @@ func (c *MetricCollectors) Build(logger *slog.Logger) error {
 
 // Close To be called by the exporter for collector cleanup.
 func (c *MetricCollectors) Close() error {
-	errs := make([]error, 0, len(c.Collectors))
+	errs := make([]error, 0, len(c.collectors))
 
-	for _, collector := range c.Collectors {
+	for _, collector := range c.collectors {
 		if err := collector.Close(); err != nil {
 			errs = append(errs, fmt.Errorf("error from close collector %s: %w", collector.GetName(), err))
 		}
 	}
 
-	app, err := c.MISession.GetApplication()
+	app, err := c.miSession.GetApplication()
 	if err != nil && !errors.Is(err, mi.ErrNotInitialized) {
 		errs = append(errs, fmt.Errorf("error from get MI application: %w", err))
 	}
 
-	if err := c.MISession.Close(); err != nil && !errors.Is(err, mi.ErrNotInitialized) {
+	if err := c.miSession.Close(); err != nil && !errors.Is(err, mi.ErrNotInitialized) {
 		errs = append(errs, fmt.Errorf("error from close MI session: %w", err))
 	}
 
@@ -226,7 +230,7 @@ func (c *MetricCollectors) Close() error {
 	return errors.Join(errs...)
 }
 
-// Close To be called by the exporter for collector cleanup.
+// initMI To be called by the exporter for collector initialization.
 func (c *MetricCollectors) initMI() error {
 	app, err := mi.Application_Initialize()
 	if err != nil {
@@ -242,10 +246,29 @@ func (c *MetricCollectors) initMI() error {
 		return fmt.Errorf("error from set locale: %w", err)
 	}
 
-	c.MISession, err = app.NewSession(destinationOptions)
+	c.miSession, err = app.NewSession(destinationOptions)
 	if err != nil {
 		return fmt.Errorf("error from create NewSession: %w", err)
 	}
 
 	return nil
 }
+
+// CloneWithCollectors To be called by the exporter for collector initialization.
+func (c *MetricCollectors) CloneWithCollectors(collectors []string) (*MetricCollectors, error) {
+	metricCollectors := &MetricCollectors{
+		collectors: maps.Clone(c.collectors),
+		miSession:  c.miSession,
+		startTime:  c.startTime,
+	}
+
+	if err := metricCollectors.Enable(collectors); err != nil {
+		return nil, err
+	}
+
+	return metricCollectors, nil
+}
+
+func (c *MetricCollectors) GetStartTime() stdtime.Time {
+	return c.startTime
+}

pkg/collector/prometheus.go

@@ -27,7 +27,7 @@ import (
 
 	"github.com/prometheus-community/windows_exporter/internal/mi"
 	"github.com/prometheus-community/windows_exporter/internal/perfdata"
-	types "github.com/prometheus-community/windows_exporter/internal/types"
+	"github.com/prometheus-community/windows_exporter/internal/types"
 	"github.com/prometheus/client_golang/prometheus"
 )
 
@@ -103,15 +103,15 @@ func (p *Prometheus) Collect(ch chan<- prometheus.Metric) {
 
 	// WaitGroup to wait for all collectors to finish
 	wg := sync.WaitGroup{}
-	wg.Add(len(p.metricCollectors.Collectors))
+	wg.Add(len(p.metricCollectors.collectors))
 
 	// Using a channel to collect the status of each collector
 	// A channel is safe to use concurrently while a map is not
-	collectorStatusCh := make(chan collectorStatus, len(p.metricCollectors.Collectors))
+	collectorStatusCh := make(chan collectorStatus, len(p.metricCollectors.collectors))
 
 	// Execute all collectors concurrently
 	// timeout handling is done in the execute function
-	for name, metricsCollector := range p.metricCollectors.Collectors {
+	for name, metricsCollector := range p.metricCollectors.collectors {
 		go func(name string, metricsCollector Collector) {
 			defer wg.Done()
 

pkg/collector/types.go

@@ -17,6 +17,7 @@ package collector
 
 import (
 	"log/slog"
+	"time"
 
 	"github.com/alecthomas/kingpin/v2"
 	"github.com/prometheus-community/windows_exporter/internal/mi"
@@ -26,9 +27,9 @@ import (
 const DefaultCollectors = "cpu,cs,memory,logical_disk,physical_disk,net,os,service,system"
 
 type MetricCollectors struct {
-	Collectors       Map
-	MISession        *mi.Session
-	PerfCounterQuery string
+	collectors Map
+	miSession  *mi.Session
+	startTime  time.Time
 }
 
 type (