fix(systemstatsmonitor): declare all labels for disk_percent_used

disk_percent_used records device_name, fs_type, mount_option and state but
only declared device_name. With per-metric label validation, Record now
rejects the undeclared labels and the metric is dropped from the export
(caught by the metriconly e2e). Declare all four labels, matching the
sibling disk_bytes_used, and add a regression test.

Author: hakman

pkg/systemstatsmonitor/disk_collector.go

@@ -157,7 +157,7 @@ func NewDiskCollectorOrDie(diskConfig *ssmtypes.DiskStatsConfig) *diskCollector
 		"Disk usage in percentage of total space",
 		"%",
 		metrics.LastValue,
-		[]string{deviceNameLabel})
+		[]string{deviceNameLabel, fsTypeLabel, mountOptionLabel, stateLabel})
 	if err != nil {
 		klog.Fatalf("Error initializing metric for %q: %v", metrics.DiskPercentUsedID, err)
 	}

pkg/systemstatsmonitor/disk_collector_test.go

@@ -19,10 +19,41 @@ package systemstatsmonitor
 import (
 	"testing"
 
+	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
+
 	ssmtypes "k8s.io/node-problem-detector/pkg/systemstatsmonitor/types"
+	"k8s.io/node-problem-detector/pkg/util/metrics"
+	otelutil "k8s.io/node-problem-detector/pkg/util/otel"
 )
 
 func TestDiskCollector(t *testing.T) {
 	dc := NewDiskCollectorOrDie(&ssmtypes.DiskStatsConfig{})
 	dc.collect()
 }
+
+// TestDiskCollectorPercentUsedLabels guards against the declared label set for
+// disk_percent_used drifting from the labels collect() records. Every label key
+// passed to Record must be in the metric's declared set, otherwise Record
+// rejects the call and the metric is silently dropped from the export.
+func TestDiskCollectorPercentUsedLabels(t *testing.T) {
+	otelutil.ResetForTesting()
+	defer otelutil.ResetForTesting()
+	otelutil.AddMetricReader(sdkmetric.NewManualReader())
+	otelutil.InitializeMeterProvider()
+
+	dc := NewDiskCollectorOrDie(&ssmtypes.DiskStatsConfig{
+		MetricsConfigs: map[string]ssmtypes.MetricConfig{
+			string(metrics.DiskPercentUsedID): {DisplayName: string(metrics.DiskPercentUsedID)},
+		},
+	})
+
+	// These are the labels collect() records disk_percent_used with.
+	if err := dc.mPercentUsed.Record(map[string]string{
+		deviceNameLabel:  "sda1",
+		fsTypeLabel:      "ext4",
+		mountOptionLabel: "rw,relatime",
+		stateLabel:       "used",
+	}, 42.0); err != nil {
+		t.Fatalf("disk_percent_used rejected the labels collect() records: %v", err)
+	}
+}