Add node deletionTimestamp metric

Adds deletionTimestamp metric, for nodes.

Signed-off-by: Pranshu Srivastava <[email protected]>

Author: rexagod

docs/node-metrics.md

@@ -12,3 +12,4 @@
 | kube_node_status_allocatable | Gauge | The allocatable for different resources of a node that are available for scheduling | `cpu`=&lt;core&gt; <br> `ephemeral_storage`=&lt;byte&gt; <br> `pods`=&lt;integer&gt; <br> `attachable_volumes_*`=&lt;byte&gt; <br> `hugepages_*`=&lt;byte&gt; <br> `memory`=&lt;byte&gt; |`node`=&lt;node-address&gt; <br> `resource`=&lt;resource-name&gt; <br> `unit`=&lt;resource-unit&gt;| STABLE |
 | kube_node_status_condition | Gauge | The condition of a cluster node | |`node`=&lt;node-address&gt; <br> `condition`=&lt;node-condition&gt; <br> `status`=&lt;true\|false\|unknown&gt; | STABLE |
 | kube_node_created | Gauge | Unix creation timestamp | seconds |`node`=&lt;node-address&gt;| STABLE |
+| kube_node_deletion_timestamp | Gauge | Unix creation timestamp | seconds |`node`=&lt;node-address&gt;| STABLE |

internal/store/node.go

@@ -44,9 +44,10 @@ var (
 
 func nodeMetricFamilies(allowAnnotationsList, allowLabelsList []string) []generator.FamilyGenerator {
 	return []generator.FamilyGenerator{
+		createNodeAnnotationsGenerator(allowAnnotationsList),
 		createNodeCreatedFamilyGenerator(),
+		createNodeDeletionTimestampFamilyGenerator(),
 		createNodeInfoFamilyGenerator(),
-		createNodeAnnotationsGenerator(allowAnnotationsList),
 		createNodeLabelsGenerator(allowLabelsList),
 		createNodeRoleFamilyGenerator(),
 		createNodeSpecTaintFamilyGenerator(),
@@ -57,6 +58,29 @@ func nodeMetricFamilies(allowAnnotationsList, allowLabelsList []string) []genera
 	}
 }
 
+func createNodeDeletionTimestampFamilyGenerator() generator.FamilyGenerator {
+	return *generator.NewFamilyGeneratorWithStability(
+		"kube_node_deletion_timestamp",
+		"Unix deletion timestamp",
+		metric.Gauge,
+		basemetrics.ALPHA,
+		"",
+		wrapNodeFunc(func(n *v1.Node) *metric.Family {
+			var ms []*metric.Metric
+
+			if n.DeletionTimestamp != nil && !n.DeletionTimestamp.IsZero() {
+				ms = append(ms, &metric.Metric{
+					Value: float64(n.DeletionTimestamp.Unix()),
+				})
+			}
+
+			return &metric.Family{
+				Metrics: ms,
+			}
+		}),
+	)
+}
+
 func createNodeCreatedFamilyGenerator() generator.FamilyGenerator {
 	return *generator.NewFamilyGeneratorWithStability(
 		"kube_node_created",