[metricbeat] Add system/entropy metricset (#12450)

* add system/entropy metricset

CHANGELOG.next.asciidoc

@@ -251,6 +251,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Always report Pod UID in the `pod` metricset. {pull}12345[12345]
 - Add Vsphere Virtual Machine operating system to `os` field in Vsphere virtualmachine module. {pull}12391[12391]
 - Add validation for elasticsearch and kibana modules' metricsets when xpack.enabled is set to true. {pull}12386[12386]
+- Add a system/entropy metricset {pull}12450[12450]
 
 *Packetbeat*
 

metricbeat/docs/fields.asciidoc

@@ -24566,6 +24566,35 @@ type: float
 Percentage of CPU time during which I/O requests were issued to the device (bandwidth utilization for the device). Device saturation occurs when this value is close to 100%.
 
 
+--
+
+[float]
+== entropy fields
+
+Available system entropy
+
+
+
+*`system.entropy.available_bits`*::
++
+--
+type: long
+
+The available bits of entropy
+
+
+--
+
+*`system.entropy.pct`*::
++
+--
+type: scaled_float
+
+format: percent
+
+The percentage of available entropy, relative to the pool size of 4096
+
+
 --
 
 [float]

metricbeat/docs/modules/system.asciidoc

@@ -116,6 +116,8 @@ The following metricsets are available:
 
 * <<metricbeat-metricset-system-diskio,diskio>>
 
+* <<metricbeat-metricset-system-entropy,entropy>>
+
 * <<metricbeat-metricset-system-filesystem,filesystem>>
 
 * <<metricbeat-metricset-system-fsstat,fsstat>>
@@ -144,6 +146,8 @@ include::system/cpu.asciidoc[]
 
 include::system/diskio.asciidoc[]
 
+include::system/entropy.asciidoc[]
+
 include::system/filesystem.asciidoc[]
 
 include::system/fsstat.asciidoc[]

metricbeat/docs/modules/system/entropy.asciidoc

@@ -0,0 +1,21 @@
+////
+This file is generated! See scripts/docs_collector.py
+////
+
+[[metricbeat-metricset-system-entropy]]
+=== System entropy metricset
+
+include::../../../module/system/entropy/_meta/docs.asciidoc[]
+
+
+==== Fields
+
+For a description of each field in the metricset, see the
+<<exported-fields-system,exported fields>> section.
+
+Here is an example document generated by this metricset:
+
+[source,json]
+----
+include::../../../module/system/entropy/_meta/data.json[]
+----

metricbeat/docs/modules_list.asciidoc

@@ -144,9 +144,10 @@ This file is generated! See scripts/docs_collector.py
 |<<metricbeat-metricset-redis-key,key>>   
 |<<metricbeat-metricset-redis-keyspace,keyspace>>   
 |<<metricbeat-module-system,System>>     |image:./images/icon-yes.png[Prebuilt dashboards are available]    |  
-.14+| .14+|  |<<metricbeat-metricset-system-core,core>>   
+.15+| .15+|  |<<metricbeat-metricset-system-core,core>>   
 |<<metricbeat-metricset-system-cpu,cpu>>   
 |<<metricbeat-metricset-system-diskio,diskio>>   
+|<<metricbeat-metricset-system-entropy,entropy>>   
 |<<metricbeat-metricset-system-filesystem,filesystem>>   
 |<<metricbeat-metricset-system-fsstat,fsstat>>   
 |<<metricbeat-metricset-system-load,load>>   

metricbeat/module/system/_meta/config.yml

@@ -8,6 +8,7 @@
     - process
     - process_summary
     - socket_summary
+    #- entropy
     #- core
     #- diskio
     #- socket

metricbeat/module/system/entropy/_meta/data.json

@@ -0,0 +1,20 @@
+{
+    "@timestamp": "2017-10-12T08:05:34.853Z",
+    "event": {
+        "dataset": "system.entropy",
+        "duration": 115000,
+        "module": "system"
+    },
+    "metricset": {
+        "name": "entropy"
+    },
+    "service": {
+        "type": "system"
+    },
+    "system": {
+        "entropy": {
+            "available_bits": 2801,
+            "pct": 0.683837890625
+        }
+    }
+}

metricbeat/module/system/entropy/_meta/docs.asciidoc

@@ -0,0 +1,5 @@
+This is the entropy metricset of the module system. It collects the amount of available entropy in bits. On kernel versions greater than 2.6, entropy will be out of a total pool size of 4096.
+
+This Metricset is available on:
+
+- linux

metricbeat/module/system/entropy/_meta/fields.yml

@@ -0,0 +1,15 @@
+- name: entropy
+  type: group
+  description: >
+    Available system entropy
+  release: ga
+  fields:
+    - name: available_bits
+      type: long
+      description: >
+        The available bits of entropy
+    - name: pct
+      type: scaled_float
+      format: percent
+      description: >
+        The percentage of available entropy, relative to the pool size of 4096

metricbeat/module/system/entropy/_meta/testdata/proc/sys/kernel/random/entropy_avail

@@ -0,0 +1 @@
+2801

metricbeat/module/system/entropy/_meta/testdata/proc/sys/kernel/random/poolsize

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

metricbeat/module/system/entropy/doc.go

@@ -0,0 +1,18 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you 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.
+
+package entropy

metricbeat/module/system/entropy/entropy.go

@@ -0,0 +1,106 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you 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 linux
+
+package entropy
+
+import (
+	"io/ioutil"
+	"path"
+	"strconv"
+	"strings"
+
+	"github.com/pkg/errors"
+
+	"github.com/elastic/beats/libbeat/common"
+	"github.com/elastic/beats/libbeat/common/cfgwarn"
+	"github.com/elastic/beats/metricbeat/mb"
+	"github.com/elastic/beats/metricbeat/module/system"
+)
+
+// init registers the MetricSet with the central registry as soon as the program
+// starts. The New function will be called later to instantiate an instance of
+// the MetricSet for each host defined in the module's configuration. After the
+// MetricSet has been created then Fetch will begin to be called periodically.
+func init() {
+	mb.Registry.MustAddMetricSet("system", "entropy", New)
+}
+
+// MetricSet holds any configuration or state information. It must implement
+// the mb.MetricSet interface. And this is best achieved by embedding
+// mb.BaseMetricSet because it implements all of the required mb.MetricSet
+// interface methods except for Fetch.
+type MetricSet struct {
+	mb.BaseMetricSet
+	randomPath string
+}
+
+// New creates a new instance of the MetricSet. New is responsible for unpacking
+// any MetricSet specific configuration options if there are any.
+func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
+	cfgwarn.Beta("The system entropy metricset is beta.")
+
+	systemModule, ok := base.Module().(*system.Module)
+	if !ok {
+		return nil, errors.New("unexpected module type")
+	}
+
+	totalPath := path.Join(systemModule.HostFS, "/proc/sys/kernel/random")
+
+	return &MetricSet{
+		BaseMetricSet: base,
+		randomPath:    totalPath,
+	}, nil
+}
+
+// Fetch methods implements the data gathering and data conversion to the right
+// format. It publishes the event which is then forwarded to the output. In case
+// of an error set the Error field of mb.Event or simply call report.Error().
+func (m *MetricSet) Fetch(report mb.ReporterV2) error {
+	entropy, err := getEntropyData(path.Join(m.randomPath, "entropy_avail"))
+	if err != nil {
+		return errors.Wrap(err, "error getting entropy")
+	}
+	poolsize, err := getEntropyData(path.Join(m.randomPath, "poolsize"))
+	if err != nil {
+		return errors.Wrap(err, "error getting poolsize")
+	}
+	report.Event(mb.Event{
+		MetricSetFields: common.MapStr{
+			"available_bits": entropy,
+			"pct":            float64(entropy) / float64(poolsize),
+		},
+	})
+
+	return nil
+}
+
+func getEntropyData(path string) (int, error) {
+	//This will be a number in the range 0 to 4096.
+	raw, err := ioutil.ReadFile(path)
+	if err != nil {
+		return 0, errors.Wrap(err, "error reading from random")
+	}
+
+	intval, err := strconv.ParseInt(strings.TrimSpace(string(raw)), 10, 64)
+	if err != nil {
+		return 0, errors.Wrap(err, "error parsing from random")
+	}
+
+	return int(intval), nil
+}

metricbeat/module/system/entropy/entropy_test.go

@@ -0,0 +1,59 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you 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 linux
+
+package entropy
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	mbtest "github.com/elastic/beats/metricbeat/mb/testing"
+	"github.com/elastic/beats/metricbeat/module/system"
+)
+
+func TestData(t *testing.T) {
+	testdata := "./_meta/testdata"
+	system.HostFS = &testdata
+	f := mbtest.NewReportingMetricSetV2Error(t, getConfig())
+	err := mbtest.WriteEventsReporterV2Error(f, t, ".")
+	if err != nil {
+		t.Fatal("write", err)
+	}
+}
+
+func TestFetch(t *testing.T) {
+	testdata := "./_meta/testdata"
+	system.HostFS = &testdata
+	f := mbtest.NewReportingMetricSetV2Error(t, getConfig())
+	events, errs := mbtest.ReportingFetchV2Error(f)
+
+	assert.Empty(t, errs)
+	if !assert.NotEmpty(t, events) {
+		t.FailNow()
+	}
+	assert.Equal(t, events[0].MetricSetFields["available_bits"], 2801)
+}
+
+func getConfig() map[string]interface{} {
+	return map[string]interface{}{
+		"module":     "system",
+		"metricsets": []string{"entropy"},
+	}
+}

metricbeat/modules.d/system.yml

@@ -11,6 +11,7 @@
     - process
     - process_summary
     - socket_summary
+    #- entropy
     #- core
     #- diskio
     #- socket