add pool size to entropy collector

Signed-off-by: binjip978 <binjip978@gmail.com>

collector/entropy_linux.go

@@ -20,10 +20,13 @@ import (
 
 	"github.com/go-kit/kit/log"
 	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/procfs"
 )
 
 type entropyCollector struct {
+	fs              procfs.FS
 	entropyAvail    *prometheus.Desc
+	entropyPoolSize *prometheus.Desc
 	logger          log.Logger
 }
 
@@ -33,23 +36,44 @@ func init() {
 
 // NewEntropyCollector returns a new Collector exposing entropy stats.
 func NewEntropyCollector(logger log.Logger) (Collector, error) {
+	fs, err := procfs.NewFS(*procPath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to open procfs: %w", err)
+	}
+
 	return &entropyCollector{
+		fs: fs,
 		entropyAvail: prometheus.NewDesc(
 			prometheus.BuildFQName(namespace, "", "entropy_available_bits"),
 			"Bits of available entropy.",
 			nil, nil,
 		),
+		entropyPoolSize: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, "", "entropy_pool_size_bytes"),
+			"Bytes of entropy pool.",
+			nil, nil,
+		),
 		logger: logger,
 	}, nil
 }
 
 func (c *entropyCollector) Update(ch chan<- prometheus.Metric) error {
-	value, err := readUintFromFile(procFilePath("sys/kernel/random/entropy_avail"))
+	stats, err := c.fs.KernelRandom()
 	if err != nil {
-		return fmt.Errorf("couldn't get entropy_avail: %s", err)
+		return fmt.Errorf("failed to get kernel random stats: %w", err)
+	}
+
+	if stats.EntropyAvaliable == nil {
+		return fmt.Errorf("couldn't get entropy_avail")
 	}
 	ch <- prometheus.MustNewConstMetric(
-		c.entropyAvail, prometheus.GaugeValue, float64(value))
+		c.entropyAvail, prometheus.GaugeValue, float64(*stats.EntropyAvaliable))
+
+	if stats.PoolSize == nil {
+		return fmt.Errorf("couldn't get entropy pool size")
+	}
+	ch <- prometheus.MustNewConstMetric(
+		c.entropyPoolSize, prometheus.GaugeValue, float64(*stats.PoolSize))
 
 	return nil
 }

collector/fixtures/e2e-output.txt

@@ -627,6 +627,9 @@ node_edac_uncorrectable_errors_total{controller="0"} 5
 # HELP node_entropy_available_bits Bits of available entropy.
 # TYPE node_entropy_available_bits gauge
 node_entropy_available_bits 1337
+# HELP node_entropy_pool_size_bytes Bytes of entropy pool.
+# TYPE node_entropy_pool_size_bytes gauge
+node_entropy_pool_size_bytes 4096
 # HELP node_exporter_build_info A metric with a constant '1' value labeled by version, revision, branch, and goversion from which node_exporter was built.
 # TYPE node_exporter_build_info gauge
 # HELP node_filefd_allocated File descriptor statistics: allocated.

collector/fixtures/proc/sys/kernel/random/poolsize

@@ -0,0 +1 @@
+4096