feat: add lsblk info collector

Dockerfile

@@ -10,7 +10,7 @@ RUN go build -ldflags="-s -w" -a -o node_exporter node_exporter.go
 
 
 FROM alpine:3.21
-RUN apk add smartmontools pciutils nvme-cli
+RUN apk add smartmontools pciutils nvme-cli util-linux
 COPY --from=builder /workspace/node_exporter /bin/node_exporter
 
 EXPOSE      9100

collector/lsblk_linux.go

@@ -0,0 +1,112 @@
+//go:build !nolsblk
+// +build !nolsblk
+
+package collector
+
+import (
+	"encoding/json"
+	"fmt"
+	"log/slog"
+	"os"
+
+	"github.com/alecthomas/kingpin/v2"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const lsblkDiskSubsystem = "disk"
+
+var lsblkPath = kingpin.Flag(
+	"collector.lsblk.path",
+	"Path to the lsblk binary.",
+).Default("/bin/lsblk").String()
+
+var lsblkTimeout = kingpin.Flag(
+	"collector.lsblk.timeout",
+	"Timeout for running lsblk.",
+).Default("5s").Duration()
+
+type lsblkCollector struct {
+	logger   *slog.Logger
+	infoDesc *prometheus.Desc
+}
+
+func init() {
+	registerCollector("lsblk", defaultEnabled, NewLsblkCollector)
+}
+
+// NewLsblkCollector returns a collector that exposes lsblk(8) JSON output as metrics.
+func NewLsblkCollector(logger *slog.Logger) (Collector, error) {
+	return &lsblkCollector{
+		logger: logger,
+		infoDesc: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, lsblkDiskSubsystem, "lsblk_info"),
+			"Non-numeric block device fields from lsblk --json, value is always 1.",
+			[]string{"name", "parent", "fstype", "mountpoint", "size", "fsused", "fsuse_percent"},
+			nil,
+		),
+	}, nil
+}
+
+type lsblkJSONRoot struct {
+	Blockdevices []lsblkJSONDevice `json:"blockdevices"`
+}
+
+type lsblkJSONDevice struct {
+	Name       string            `json:"name"`
+	Size       *string           `json:"size"`
+	Fstype     *string           `json:"fstype"`
+	Mountpoint *string           `json:"mountpoint"`
+	Fsused     *string           `json:"fsused"`
+	FsusePct   *string           `json:"fsuse%"`
+	Children   []lsblkJSONDevice `json:"children"`
+}
+
+func lsblkStringPtr(s *string) string {
+	if s == nil {
+		return ""
+	}
+	return *s
+}
+
+func (c *lsblkCollector) emitRecursive(ch chan<- prometheus.Metric, devices []lsblkJSONDevice, parent string) {
+	for _, d := range devices {
+		ch <- prometheus.MustNewConstMetric(c.infoDesc, prometheus.GaugeValue, 1,
+			d.Name,
+			parent,
+			lsblkStringPtr(d.Fstype),
+			lsblkStringPtr(d.Mountpoint),
+			lsblkStringPtr(d.Size),
+			lsblkStringPtr(d.Fsused),
+			lsblkStringPtr(d.FsusePct),
+		)
+		if len(d.Children) > 0 {
+			c.emitRecursive(ch, d.Children, d.Name)
+		}
+	}
+}
+
+func (c *lsblkCollector) Update(ch chan<- prometheus.Metric) error {
+	path := *lsblkPath
+	if path == "" {
+		return fmt.Errorf("collector.lsblk.path is empty")
+	}
+	if _, err := os.Stat(path); err != nil {
+		c.logger.Debug("lsblk binary not available", "path", path, "err", err)
+		return ErrNoData
+	}
+
+	args := []string{"--json", "-o", "NAME,SIZE,FSTYPE,MOUNTPOINT,FSUSED,FSUSE%"}
+	cmd := execCommand(path, args...)
+	out, err := CombinedOutputTimeout(cmd, *lsblkTimeout)
+	if err != nil {
+		return fmt.Errorf("lsblk failed: %w", err)
+	}
+
+	var root lsblkJSONRoot
+	if err := json.Unmarshal(out, &root); err != nil {
+		return fmt.Errorf("lsblk json parse error: %w", err)
+	}
+
+	c.emitRecursive(ch, root.Blockdevices, "")
+	return nil
+}

end-to-end-test.sh

@@ -94,6 +94,7 @@ supported_enabled_collectors=$(supported_collectors "${enabled_collectors}")
 disabled_collectors=$(cat << COLLECTORS
   selinux
   filesystem
+  lsblk
   timex
   uname
 COLLECTORS