add include/exclude options to logind collector

collector/logind_linux.go

@@ -22,6 +22,7 @@ import (
 	"slices"
 	"strconv"
 
+	"github.com/alecthomas/kingpin/v2"
 	"github.com/godbus/dbus/v5"
 	"github.com/prometheus/client_golang/prometheus"
 )
@@ -38,6 +39,8 @@ var (
 	attrRemoteValues = []string{"true", "false"}
 	attrTypeValues   = []string{"other", "unspecified", "tty", "x11", "wayland", "mir", "web"}
 	attrClassValues  = []string{"other", "user", "greeter", "lock-screen", "background"}
+	logindClassInclude = kingpin.Flag("collector.logind.class-include", "Regexp of logind session classes to include (mutually exclusive with class-exclude).").String()
+	logindClassExclude = kingpin.Flag("collector.logind.class-exclude", "Regexp of logind session classes to exclude (mutually exclusive with class-include).").String()
 
 	sessionsDesc = prometheus.NewDesc(
 		prometheus.BuildFQName(namespace, logindSubsystem, "sessions"),
@@ -46,6 +49,7 @@ var (
 )
 
 type logindCollector struct {
+	classFilter deviceFilter
 	logger *slog.Logger
 }
 
@@ -87,7 +91,10 @@ func init() {
 
 // NewLogindCollector returns a new Collector exposing logind statistics.
 func NewLogindCollector(logger *slog.Logger) (Collector, error) {
-	return &logindCollector{logger}, nil
+    return &logindCollector{
+        logger:      logger,
+        classFilter: newDeviceFilter(*logindClassExclude, *logindClassInclude),
+    }, nil
 }
 
 func (lc *logindCollector) Update(ch chan<- prometheus.Metric) error {
@@ -97,10 +104,10 @@ func (lc *logindCollector) Update(ch chan<- prometheus.Metric) error {
 	}
 	defer c.conn.Close()
 
-	return collectMetrics(ch, c)
+	return collectMetrics(ch, c, lc)
 }
 
-func collectMetrics(ch chan<- prometheus.Metric, c logindInterface) error {
+func collectMetrics(ch chan<- prometheus.Metric, c logindInterface, lc *logindCollector) error {
 	seats, err := c.listSeats()
 	if err != nil {
 		return fmt.Errorf("unable to get seats: %w", err)
@@ -123,6 +130,9 @@ func collectMetrics(ch chan<- prometheus.Metric, c logindInterface) error {
 	for _, remote := range attrRemoteValues {
 		for _, sessionType := range attrTypeValues {
 			for _, class := range attrClassValues {
+				if lc.classFilter.ignored(class) {
+					continue
+				}
 				for _, seat := range seats {
 					count := sessions[logindSession{seat, remote, sessionType, class}]
 

collector/logind_linux_test.go

@@ -102,3 +102,40 @@ func TestLogindCollectorCollectMetrics(t *testing.T) {
 		t.Errorf("collectMetrics did not generate the expected number of metrics: got %d, expected %d.", count, expected)
 	}
 }
+
+func TestLogindCollectorCollectMetricsWithFilter(t *testing.T) {
+	ch := make(chan prometheus.Metric)
+	// Create a dummy collector with a classFilter that excludes "greeter"
+	collector := &logindCollector{
+			classFilter: deviceFilter{
+					ignorePattern: regexp.MustCompile("greeter"),
+			},
+	}
+
+	// Wrap collectMetrics call in a goroutine feeding the metrics channel
+	go func() {
+			err := collectMetrics(ch, &testLogindInterface{})
+			if err != nil {
+					t.Errorf("collectMetrics returned error: %v", err)
+			}
+			close(ch)
+	}()
+
+	seenClasses := make(map[string]bool)
+	count := 0
+	for metric := range ch {
+			count++
+			desc := metric.Desc().String()
+			// Extract class label from the metric Desc string (approximate)
+			// The label list appears as '{seat=...,remote=...,type=...,class=...}'
+			// We'll parse class label from the Desc string for simplicity here:
+			// For a formal approach, you can use a prometheus.Metric introspection library.
+
+			if strings.Contains(desc, "class=\"greeter\"") {
+					t.Errorf("metric with excluded class 'greeter' was emitted")
+			}
+	}
+	if count == 0 {
+			t.Errorf("no metrics were emitted")
+	}
+}