[Metricbeat][Kubernetes Volume] Add pvc reference to distinguish ephemeral from persistent volumes (#38839)

* Kubernetes add pvc reference in the kubernetes.volume dataset if present

* Reuse field kubernetes.persistentvolumeclaim instead of creating a new one

* Add only persistentvolumeclaim name and no namespace (that is redundant with the kubernetes.namespace)

* Add test to see if persistentvolumeclaim name is extracted

* Add a separate test for pvc

* Add changelog entry for the PR

* Add the persistentvolume claim field

* Run mage update to update the fields

* Remove the duplicate definition of the field kubernetes.persistentvolumeclaim.name

* Remove newline

* Fix key from kubernetes.volume.persistentvolumeclaim.name to kubernetes.persistentvolume

* Fix unit test after changing the populated field name

* Removed printf function

* Remove empty lines added by mistake

Author: herrBez

CHANGELOG.next.asciidoc

@@ -191,6 +191,7 @@ https://github.com/elastic/beats/compare/v8.8.1\...main[Check the HEAD diff]
 - Enable early event encoding in the Elasticsearch output, improving cpu and memory use {pull}38572[38572]
 - The environment variable `BEATS_ADD_CLOUD_METADATA_PROVIDERS` overrides configured/default `add_cloud_metadata` providers {pull}38669[38669]
 - Introduce log message for not supported annotations for Hints based autodiscover {pull}38213[38213]
+- Add persistent volume claim name to volume if available {pull}38839[38839]
 
 
 *Auditbeat*

metricbeat/module/kubernetes/_meta/test/stats_summary.json

@@ -122,7 +122,21 @@
       "inodes": 473560,
       "inodesUsed": 9,
       "name": "default-token-sg8x5"
-     }
+     },
+     {
+        "time": "2024-04-09T17:34:17Z",
+        "availableBytes": 31509590016,
+        "capacityBytes": 31526391808,
+        "usedBytes": 24576,
+        "inodesFree": 1966069,
+        "inodes": 1966080,
+        "inodesUsed": 11,
+        "name": "pvc-demo-vol",
+        "pvcRef": {
+          "name": "pvc-demo",
+          "namespace": "default"
+        }
+      }
     ]
    }
   ]

metricbeat/module/kubernetes/types.go

@@ -131,6 +131,10 @@ type Summary struct {
 			InodesUsed     uint64 `json:"inodesUsed"`
 			Name           string `json:"name"`
 			UsedBytes      uint64 `json:"usedBytes"`
+			PvcRef         struct {
+				Name      string `json:"name"`
+				Namespace string `json:"namespace"`
+			} `json:"pvcRef"`
 		} `json:"volume"`
 	} `json:"pods"`
 }

metricbeat/module/kubernetes/volume/data.go

@@ -75,6 +75,9 @@ func eventMapping(content []byte, logger *logp.Logger) ([]mapstr.M, error) {
 			if volume.Inodes > 0 {
 				kubernetes2.ShouldPut(volumeEvent, "fs.inodes.pct", float64(volume.InodesUsed)/float64(volume.Inodes), logger)
 			}
+			if volume.PvcRef.Name != "" {
+				kubernetes2.ShouldPut(volumeEvent, mb.ModuleDataKey+".persistentvolumeclaim.name", volume.PvcRef.Name, logger)
+			}
 			events = append(events, volumeEvent)
 		}
 

metricbeat/module/kubernetes/volume/volume_test.go

@@ -26,6 +26,7 @@ import (
 
 	"github.com/stretchr/testify/assert"
 
+	"github.com/elastic/beats/v7/metricbeat/mb"
 	"github.com/elastic/elastic-agent-libs/logp"
 	"github.com/elastic/elastic-agent-libs/mapstr"
 )
@@ -44,23 +45,32 @@ func TestEventMapping(t *testing.T) {
 	events, err := eventMapping(body, logger)
 	assert.NoError(t, err, "error mapping "+testFile)
 
-	assert.Len(t, events, 1, "got wrong number of events")
+	assert.Len(t, events, 2, "got wrong number of events")
 
-	testCases := map[string]interface{}{
-		"name": "default-token-sg8x5",
-
-		"fs.available.bytes": 1939689472,
-		"fs.capacity.bytes":  1939701760,
-		"fs.used.bytes":      12288,
-		"fs.used.pct":        float64(12288) / float64(1939701760),
-		"fs.inodes.used":     9,
-		"fs.inodes.free":     473551,
-		"fs.inodes.count":    473560,
-		"fs.inodes.pct":      float64(9) / float64(473560),
+	testCases := []map[string]interface{}{
+		// Test for ephemeral volume
+		{
+			"name":               "default-token-sg8x5",
+			"fs.available.bytes": 1939689472,
+			"fs.capacity.bytes":  1939701760,
+			"fs.used.bytes":      12288,
+			"fs.used.pct":        float64(12288) / float64(1939701760),
+			"fs.inodes.used":     9,
+			"fs.inodes.free":     473551,
+			"fs.inodes.count":    473560,
+			"fs.inodes.pct":      float64(9) / float64(473560),
+		},
+		// Test for the persistent volume claim
+		{
+			mb.ModuleDataKey + ".persistentvolumeclaim.name": "pvc-demo",
+			"name": "pvc-demo-vol",
+		},
 	}
 
-	for k, v := range testCases {
-		testValue(t, events[0], k, v)
+	for i := range testCases {
+		for k, v := range testCases[i] {
+			testValue(t, events[i], k, v)
+		}
 	}
 }