lib/promscrape/discovery/kubernetes: localize Bookmark parsing code

This is a follow-up for e772d1c920

lib/promscrape/discovery/kubernetes/api_watcher.go

@@ -31,7 +31,6 @@ type WatchEvent struct {
 type object interface {
 	key() string
 	getTargetLabels(aw *apiWatcher) []map[string]string
-	resourceVersion() string
 }
 
 // parseObjectFunc must parse object from the given data.
@@ -397,13 +396,13 @@ func (uw *urlWatcher) readObjectUpdateStream(r io.Reader) error {
 		if err := d.Decode(&we); err != nil {
 			return err
 		}
-		o, err := uw.parseObject(we.Object)
-		if err != nil {
-			return err
-		}
-		key := o.key()
 		switch we.Type {
 		case "ADDED", "MODIFIED":
+			o, err := uw.parseObject(we.Object)
+			if err != nil {
+				return err
+			}
+			key := o.key()
 			uw.objectsByKey.update(key, o)
 			labels := o.getTargetLabels(aw)
 			swos := getScrapeWorkObjectsForLabels(aw.swcFunc, labels)
@@ -415,19 +414,44 @@ func (uw *urlWatcher) readObjectUpdateStream(r io.Reader) error {
 			}
 			uw.mu.Unlock()
 		case "DELETED":
+			o, err := uw.parseObject(we.Object)
+			if err != nil {
+				return err
+			}
+			key := o.key()
 			uw.objectsByKey.remove(key)
 			uw.mu.Lock()
 			delete(uw.swosByKey, key)
 			uw.mu.Unlock()
 		case "BOOKMARK":
 			// See https://kubernetes.io/docs/reference/using-api/api-concepts/#watch-bookmarks
-			uw.setResourceVersion(o.resourceVersion())
+			bm, err := parseBookmark(we.Object)
+			if err != nil {
+				return fmt.Errorf("cannot parse bookmark from %q: %w", we.Object, err)
+			}
+			uw.setResourceVersion(bm.Metadata.ResourceVersion)
 		default:
 			return fmt.Errorf("unexpected WatchEvent type %q for role %q", we.Type, uw.role)
 		}
 	}
 }
 
+// Bookmark is a bookmark from Kubernetes Watch API.
+// See https://kubernetes.io/docs/reference/using-api/api-concepts/#watch-bookmarks
+type Bookmark struct {
+	Metadata struct {
+		ResourceVersion string
+	}
+}
+
+func parseBookmark(data []byte) (*Bookmark, error) {
+	var bm Bookmark
+	if err := json.Unmarshal(data, &bm); err != nil {
+		return nil, err
+	}
+	return &bm, nil
+}
+
 func getAPIPaths(role string, namespaces []string, selectors []Selector) []string {
 	objectName := getObjectNameByRole(role)
 	if objectName == "nodes" || len(namespaces) == 0 {

lib/promscrape/discovery/kubernetes/api_watcher_test.go

@@ -160,3 +160,15 @@ func TestGetAPIPaths(t *testing.T) {
 		"/apis/networking.k8s.io/v1beta1/namespaces/y/ingresses?labelSelector=cde%2Cbaaa&fieldSelector=abc",
 	})
 }
+
+func TestParseBookmark(t *testing.T) {
+	data := `{"kind": "Pod", "apiVersion": "v1", "metadata": {"resourceVersion": "12746"} }`
+	bm, err := parseBookmark([]byte(data))
+	if err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
+	expectedResourceVersion := "12746"
+	if bm.Metadata.ResourceVersion != expectedResourceVersion {
+		t.Fatalf("unexpected resourceVersion; got %q; want %q", bm.Metadata.ResourceVersion, expectedResourceVersion)
+	}
+}

lib/promscrape/discovery/kubernetes/common_types.go

@@ -8,7 +8,6 @@ import (
 //
 // See https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.17/#objectmeta-v1-meta
 type ObjectMeta struct {
-	ResourceVersion string
 	Name            string
 	Namespace       string
 	UID             string

lib/promscrape/discovery/kubernetes/endpoints.go

@@ -47,10 +47,6 @@ type Endpoints struct {
 	Subsets  []EndpointSubset
 }
 
-func (eps *Endpoints) resourceVersion() string {
-	return eps.Metadata.ResourceVersion
-}
-
 // EndpointSubset implements k8s endpoint subset.
 //
 // See https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.17/#endpointsubset-v1-core

lib/promscrape/discovery/kubernetes/endpointslices.go

@@ -161,10 +161,6 @@ type EndpointSlice struct {
 	Ports       []EndpointPort
 }
 
-func (eps *EndpointSlice) resourceVersion() string {
-	return eps.Metadata.ResourceVersion
-}
-
 // Endpoint implements kubernetes object endpoint for endpoint slice.
 // https://v1-17.docs.kubernetes.io/docs/reference/generated/kubernetes-api/v1.17/#endpoint-v1beta1-discovery-k8s-io
 type Endpoint struct {

lib/promscrape/discovery/kubernetes/ingress.go

@@ -45,10 +45,6 @@ type Ingress struct {
 	Spec     IngressSpec
 }
 
-func (ig *Ingress) resourceVersion() string {
-	return ig.Metadata.ResourceVersion
-}
-
 // IngressSpec represents ingress spec in k8s.
 //
 // See https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.17/#ingressspec-v1beta1-extensions

lib/promscrape/discovery/kubernetes/node.go

@@ -48,10 +48,6 @@ type Node struct {
 	Status   NodeStatus
 }
 
-func (n *Node) resourceVersion() string {
-	return n.Metadata.ResourceVersion
-}
-
 // NodeStatus represents NodeStatus from k8s API.
 //
 // See https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.17/#nodestatus-v1-core

lib/promscrape/discovery/kubernetes/pod.go

@@ -50,10 +50,6 @@ type Pod struct {
 	Status   PodStatus
 }
 
-func (p *Pod) resourceVersion() string {
-	return p.Metadata.ResourceVersion
-}
-
 // PodSpec implements k8s pod spec.
 //
 // See https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.17/#podspec-v1-core

lib/promscrape/discovery/kubernetes/service.go

@@ -47,10 +47,6 @@ type Service struct {
 	Spec     ServiceSpec
 }
 
-func (s *Service) resourceVersion() string {
-	return s.Metadata.ResourceVersion
-}
-
 // ServiceSpec is k8s service spec.
 //
 // See https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.17/#servicespec-v1-core