Introduce entropy collector for Linux

collector/entropy_linux.go

@@ -0,0 +1,53 @@
+// Copyright 2015 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build !noentropy
+
+package collector
+
+import (
+	"fmt"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+type entropyCollector struct {
+	entropy_avail *prometheus.Desc
+}
+
+func init() {
+	Factories["entropy"] = NewEntropyCollector
+}
+
+// Takes a prometheus registry and returns a new Collector exposing
+// entropy stats
+func NewEntropyCollector() (Collector, error) {
+	return &entropyCollector{
+		entropy_avail: prometheus.NewDesc(
+			prometheus.BuildFQName(Namespace, "", "entropy_avail"),
+			"Bits of available entropy.",
+			nil, nil,
+		),
+	}, nil
+}
+
+func (c *entropyCollector) Update(ch chan<- prometheus.Metric) (err error) {
+	value, err := readUintFromFile(procFilePath("sys/kernel/random/entropy_avail"))
+	if err != nil {
+		return fmt.Errorf("couldn't get entropy_avail: %s", err)
+	}
+	ch <- prometheus.MustNewConstMetric(
+		c.entropy_avail, prometheus.GaugeValue, float64(value))
+
+	return nil
+}

collector/fixtures/e2e-output.txt

@@ -362,6 +362,9 @@ node_disk_writes_merged{device="mmcblk0p2"} 0
 node_disk_writes_merged{device="sda"} 1.1134226e+07
 node_disk_writes_merged{device="sr0"} 0
 node_disk_writes_merged{device="vda"} 2.0711856e+07
+# HELP node_entropy_avail Bits of available entropy.
+# TYPE node_entropy_avail gauge
+node_entropy_avail 1337
 # HELP node_exporter_scrape_duration_seconds node_exporter: Duration of a scrape job.
 # TYPE node_exporter_scrape_duration_seconds summary
 node_exporter_scrape_duration_seconds{collector="bonding",result="success",quantile="0.5"} 7.481600000000001e-05

collector/fixtures/proc/sys/kernel/random/entropy_avail

@@ -0,0 +1 @@
+1337