Add refresh list of perf counters at every fetch elastic#13091

CHANGELOG.next.asciidoc

@@ -320,6 +320,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Add AWS elb metricset. {pull}12952[12952] {issue}11701[11701]
 - Add AWS ebs metricset. {pull}13167[13167] {issue}11699[11699]
 - Add rate metrics for ec2 metricset. {pull}13203[13203]
+- Add refresh list of perf counters at every fetch {issue}13091[13091]
 
 *Packetbeat*
 

metricbeat/module/windows/perfmon/pdh_query_windows.go

@@ -67,7 +67,7 @@ func (q *Query) Open() error {
 // AddCounter adds the specified counter to the query.
 func (q *Query) AddCounter(counterPath string, counter CounterConfig, wildcard bool) error {
 	if _, found := q.counters[counterPath]; found {
-		return errors.Errorf("counter %s has been already added", counterPath)
+		return nil
 	}
 	var err error
 	var instanceName string
@@ -130,6 +130,9 @@ func (q *Query) ExpandWildCardPath(wildCardPath string) ([]string, error) {
 	if err != nil {
 		return nil, err
 	}
+	if expdPaths == nil {
+		return nil, errors.New("No counter paths found")
+	}
 	return UTF16ToStringArray(expdPaths), nil
 }
 

metricbeat/module/windows/perfmon/perfmon.go

@@ -20,9 +20,8 @@
 package perfmon
 
 import (
-	"strings"
-
 	"github.com/pkg/errors"
+	"strings"
 
 	"github.com/elastic/beats/libbeat/common/cfgwarn"
 	"github.com/elastic/beats/libbeat/logp"
@@ -80,7 +79,6 @@ func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
 	if err != nil {
 		return nil, errors.Wrap(err, "initialization of reader failed")
 	}
-
 	return &MetricSet{
 		BaseMetricSet: base,
 		reader:        reader,
@@ -89,13 +87,17 @@ func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
 }
 
 func (m *MetricSet) Fetch(report mb.ReporterV2) {
+	var err error
+	// refresh performance counter list
+	if m.reader.executed {
+		err = m.reader.RefreshCounterPaths()
+	}
 	events, err := m.reader.Read()
 	if err != nil {
 		m.log.Debugw("Failed reading counters", "error", err)
 		err = errors.Wrap(err, "failed reading counters")
 		report.Error(err)
 	}
-
 	for _, event := range events {
 		report.Event(event)
 	}

metricbeat/module/windows/perfmon/reader.go

@@ -37,12 +37,12 @@ var (
 
 // Reader will contain the config options
 type Reader struct {
-	query             Query             // PDH Query
-	instanceLabel     map[string]string // Mapping of counter path to key used for the label (e.g. processor.name)
-	measurement       map[string]string // Mapping of counter path to key used for the value (e.g. processor.cpu_time).
-	executed          bool              // Indicates if the query has been executed.
-	log               *logp.Logger      //
-	groupMeasurements bool              // Indicates if measurements with the same instance label should be sent in the same event
+	query         Query             // PDH Query
+	instanceLabel map[string]string // Mapping of counter path to key used for the label (e.g. processor.name)
+	measurement   map[string]string // Mapping of counter path to key used for the value (e.g. processor.cpu_time).
+	executed      bool              // Indicates if the query has been executed.
+	log           *logp.Logger      //
+	config        Config            // Metricset configuration
 }
 
 // NewReader creates a new instance of Reader.
@@ -53,11 +53,11 @@ func NewReader(config Config) (*Reader, error) {
 	}
 
 	r := &Reader{
-		query:             query,
-		instanceLabel:     map[string]string{},
-		measurement:       map[string]string{},
-		log:               logp.NewLogger("perfmon"),
-		groupMeasurements: config.GroupMeasurements,
+		query:         query,
+		instanceLabel: map[string]string{},
+		measurement:   map[string]string{},
+		log:           logp.NewLogger("perfmon"),
+		config:        config,
 	}
 	for _, counter := range config.CounterConfig {
 		childQueries, err := query.ExpandWildCardPath(counter.Query)
@@ -94,8 +94,38 @@ func NewReader(config Config) (*Reader, error) {
 	return r, nil
 }
 
+// RefreshCounterPaths will recheck for any new instances and add them to the counter list
+func (r *Reader) RefreshCounterPaths() error {
+	for _, counter := range r.config.CounterConfig {
+		if !strings.Contains(counter.Query, "*") {
+			continue
+		}
+		childQueries, err := r.query.ExpandWildCardPath(counter.Query)
+		if err == nil && len(childQueries) >= 1 && !strings.Contains(childQueries[0], "*") {
+			for _, v := range childQueries {
+				if err := r.query.AddCounter(v, counter, len(childQueries) > 1); err != nil {
+					r.query.Close()
+					return errors.Wrapf(err, `failed to add counter (query="%v")`, counter.Query)
+				}
+				r.instanceLabel[v] = counter.InstanceLabel
+				r.measurement[v] = counter.MeasurementLabel
+			}
+			// Some counters, such as rate counters, require two counter values in order to compute a displayable value. In this case we must call PdhCollectQueryData twice before calling PdhGetFormattedCounterValue.
+			// For more information, see Collecting Performance Data (https://docs.microsoft.com/en-us/windows/desktop/PerfCtrs/collecting-performance-data).
+			if err := r.query.CollectData(); err != nil {
+				return errors.Wrap(err, "failed querying counter values")
+			}
+		}
+	}
+	return nil
+}
+
 // Read executes a query and returns those values in an event.
 func (r *Reader) Read() ([]mb.Event, error) {
+	//if r.config.IgnoreNECounters && len(r.query.counters) == 0 {
+	//	return nil, nil
+	//}
+
 	if err := r.query.CollectData(); err != nil {
 		return nil, errors.Wrap(err, "failed querying counter values")
 	}
@@ -119,7 +149,7 @@ func (r *Reader) Read() ([]mb.Event, error) {
 			}
 
 			var eventKey string
-			if r.groupMeasurements && val.Err == nil {
+			if r.config.GroupMeasurements && val.Err == nil {
 				// Send measurements with the same instance label as part of the same event
 				eventKey = val.Instance
 			} else {