Kubernetes service discovery: add provider ID label (#9603)

When using Kubernetes on cloud providers, nodes will have the
spec.providerID field populated to contain the cloud provider specific
name of the EC2/GCE/...  instance.

Let's expose this information as an additional label, so that it's
easier to annotate metrics and alerts to contain the cloud provider
specific name of the instance to which it pertains.

Signed-off-by: Ed Schouten <eschouten@apple.com>

discovery/kubernetes/node.go

@@ -149,6 +149,7 @@ func nodeSourceFromName(name string) string {
 
 const (
 	nodeNameLabel               = metaLabelPrefix + "node_name"
+	nodeProviderIDLabel         = metaLabelPrefix + "node_provider_id"
 	nodeLabelPrefix             = metaLabelPrefix + "node_label_"
 	nodeLabelPresentPrefix      = metaLabelPrefix + "node_labelpresent_"
 	nodeAnnotationPrefix        = metaLabelPrefix + "node_annotation_"
@@ -161,6 +162,7 @@ func nodeLabels(n *apiv1.Node) model.LabelSet {
 	ls := make(model.LabelSet, 2*(len(n.Labels)+len(n.Annotations))+1)
 
 	ls[nodeNameLabel] = lv(n.Name)
+	ls[nodeProviderIDLabel] = lv(n.Spec.ProviderID)
 
 	for k, v := range n.Labels {
 		ln := strutil.SanitizeLabelName(k)

discovery/kubernetes/node_test.go

@@ -25,13 +25,16 @@ import (
 	"github.com/prometheus/prometheus/discovery/targetgroup"
 )
 
-func makeNode(name, address string, labels, annotations map[string]string) *v1.Node {
+func makeNode(name, address, providerID string, labels, annotations map[string]string) *v1.Node {
 	return &v1.Node{
 		ObjectMeta: metav1.ObjectMeta{
 			Name:        name,
 			Labels:      labels,
 			Annotations: annotations,
 		},
+		Spec: v1.NodeSpec{
+			ProviderID: providerID,
+		},
 		Status: v1.NodeStatus{
 			Addresses: []v1.NodeAddress{
 				{
@@ -49,7 +52,7 @@ func makeNode(name, address string, labels, annotations map[string]string) *v1.N
 }
 
 func makeEnumeratedNode(i int) *v1.Node {
-	return makeNode(fmt.Sprintf("test%d", i), "1.2.3.4", map[string]string{}, map[string]string{})
+	return makeNode(fmt.Sprintf("test%d", i), "1.2.3.4", fmt.Sprintf("aws:///de-west-3a/i-%d", i), map[string]string{}, map[string]string{})
 }
 
 func TestNodeDiscoveryBeforeStart(t *testing.T) {
@@ -61,6 +64,7 @@ func TestNodeDiscoveryBeforeStart(t *testing.T) {
 			obj := makeNode(
 				"test",
 				"1.2.3.4",
+				"aws:///nl-north-7b/i-03149834983492827",
 				map[string]string{"test-label": "testvalue"},
 				map[string]string{"test-annotation": "testannotationvalue"},
 			)
@@ -78,6 +82,7 @@ func TestNodeDiscoveryBeforeStart(t *testing.T) {
 				},
 				Labels: model.LabelSet{
 					"__meta_kubernetes_node_name":                              "test",
+					"__meta_kubernetes_node_provider_id":                       "aws:///nl-north-7b/i-03149834983492827",
 					"__meta_kubernetes_node_label_test_label":                  "testvalue",
 					"__meta_kubernetes_node_labelpresent_test_label":           "true",
 					"__meta_kubernetes_node_annotation_test_annotation":        "testannotationvalue",
@@ -109,7 +114,8 @@ func TestNodeDiscoveryAdd(t *testing.T) {
 					},
 				},
 				Labels: model.LabelSet{
-					"__meta_kubernetes_node_name": "test1",
+					"__meta_kubernetes_node_name":        "test1",
+					"__meta_kubernetes_node_provider_id": "aws:///de-west-3a/i-1",
 				},
 				Source: "node/test1",
 			},
@@ -146,6 +152,7 @@ func TestNodeDiscoveryUpdate(t *testing.T) {
 			obj2 := makeNode(
 				"test0",
 				"1.2.3.4",
+				"aws:///fr-south-1c/i-49508290343823952",
 				map[string]string{"Unschedulable": "true"},
 				map[string]string{},
 			)
@@ -165,6 +172,7 @@ func TestNodeDiscoveryUpdate(t *testing.T) {
 					"__meta_kubernetes_node_label_Unschedulable":        "true",
 					"__meta_kubernetes_node_labelpresent_Unschedulable": "true",
 					"__meta_kubernetes_node_name":                       "test0",
+					"__meta_kubernetes_node_provider_id":                "aws:///fr-south-1c/i-49508290343823952",
 				},
 				Source: "node/test0",
 			},

docs/configuration/configuration.md

@@ -1513,6 +1513,7 @@ node object in the address type order of `NodeInternalIP`, `NodeExternalIP`,
 Available meta labels:
 
 * `__meta_kubernetes_node_name`: The name of the node object.
+* `__meta_kubernetes_node_provider_id`: The cloud provider's name for the node object.
 * `__meta_kubernetes_node_label_<labelname>`: Each label from the node object.
 * `__meta_kubernetes_node_labelpresent_<labelname>`: `true` for each label from the node object.
 * `__meta_kubernetes_node_annotation_<annotationname>`: Each annotation from the node object.