feat: Support EventRegarding & EventRelated relationship

Signed-off-by: Justin Toh <tohjustin@hotmail.com>

.golangci.yaml

@@ -12,6 +12,8 @@ linters:
     - sqlclosecheck    # exclude 'sql' preset
     - exhaustivestruct
     - gochecknoglobals
+    - goconst
+    - godox
     - goerr113
     - gomnd
     - gomoddirectives

README.md

@@ -33,6 +33,7 @@ List of supported relationships used for discovering dependent objects:
 
 - Kubernetes
   - [Controller References](https://github.com/kubernetes/community/blob/master/contributors/design-proposals/api-machinery/controller-ref.md) & [Owner References](https://kubernetes.io/docs/concepts/overview/working-with-objects/owners-dependents/)
+  - [Event Regarding & Related References](https://kubernetes.io/docs/reference/kubernetes-api/cluster-resources/event-v1/)
 - Helm (Coming Soon)
 
 ## Installation

pkg/cmd/lineage/graph.go

@@ -3,8 +3,11 @@ package lineage
 import (
 	"sort"
 
+	corev1 "k8s.io/api/core/v1"
+	eventsv1 "k8s.io/api/events/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	unstructuredv1 "k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/klog/v2"
 )
@@ -15,7 +18,7 @@ func (s sortableStringSlice) Len() int           { return len(s) }
 func (s sortableStringSlice) Less(i, j int) bool { return s[i] < s[j] }
 func (s sortableStringSlice) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
 
-// Relationship represents a relationship type.
+// Relationship represents a relationship type between two Kubernetes objects.
 type Relationship string
 
 // RelationshipSet contains a set of relationships.
@@ -47,28 +50,50 @@ type Node struct {
 type NodeMap map[types.UID]*Node
 
 const (
+	// Kubernetes Event relationships.
+	RelationshipEventRegarding Relationship = "EventRegarding"
+	RelationshipEventRelated   Relationship = "EventRelated"
+
 	// Kubernetes Owner-Dependent relationships.
 	RelationshipControllerRef Relationship = "ControllerReference"
 	RelationshipOwnerRef      Relationship = "OwnerReference"
 )
 
 // resolveDependents resolves all dependents of the provided root object and
 // returns a relationship tree.
-//nolint:funlen,gocognit
+//nolint:funlen,gocognit,gocyclo
 func resolveDependents(objects []unstructuredv1.Unstructured, rootUID types.UID) NodeMap {
 	// Create global node map of all objects
 	globalMap := NodeMap{}
 	for ix, o := range objects {
+		gvk := o.GroupVersionKind()
 		node := Node{
 			Unstructured:    &objects[ix],
 			UID:             o.GetUID(),
+			Name:            o.GetName(),
+			Namespace:       o.GetNamespace(),
+			Group:           gvk.Group,
+			Kind:            gvk.Kind,
 			OwnerReferences: o.GetOwnerReferences(),
 			Dependents:      map[types.UID]RelationshipSet{},
 		}
 		globalMap[node.UID] = &node
+
+		if node.Group == "" && node.Kind == "Node" {
+			// Node events sent by the Kubelet uses the node's name as the
+			// ObjectReference UID, so we include them as keys in our global map to
+			// support lookup by nodename
+			globalMap[types.UID(node.Name)] = &node
+			// Node events sent by the kube-proxy uses the node's hostname as the
+			// ObjectReference UID, so we include them as keys in our global map to
+			// support lookup by hostname
+			if hostname, ok := o.GetLabels()["kubernetes.io/hostname"]; ok {
+				globalMap[types.UID(hostname)] = &node
+			}
+		}
 	}
 
-	// Populate dependents data for every node
+	// Populate dependents based on ControllerRef & OwnerRef relationships
 	for _, node := range globalMap {
 		uid, ownerRefs := node.UID, node.OwnerReferences
 		for _, ref := range ownerRefs {
@@ -86,6 +111,53 @@ func resolveDependents(objects []unstructuredv1.Unstructured, rootUID types.UID)
 		}
 	}
 
+	// Populate dependents based on EventRegarding & EventRelated relationships
+	// TODO: It's possible to have events to be in a different namespace from the
+	//       its referenced object, so update the resource fetching logic to
+	//       always try to fetch events at the cluster scope for event resources
+	var evUID, regUID, relUID types.UID
+	var err error
+	for _, node := range globalMap {
+		switch {
+		case node.Group == "" && node.Kind == "Event":
+			evUID = node.UID
+			regUID, err = getEventCoreReferenceUID(node.Unstructured)
+			if err != nil || len(regUID) == 0 {
+				klog.V(4).Infof("Failed to get object reference for event named \"%s\" in namespace \"%s\"", node.Name, node.Namespace)
+				continue
+			}
+			if ref, ok := globalMap[regUID]; ok {
+				if _, ok := ref.Dependents[evUID]; !ok {
+					ref.Dependents[evUID] = RelationshipSet{}
+				}
+				ref.Dependents[evUID][RelationshipEventRegarding] = struct{}{}
+			}
+		case node.Group == "events.k8s.io" && node.Kind == "Event":
+			evUID = node.UID
+			regUID, relUID, err = getEventReferenceUIDs(node.Unstructured)
+			if err != nil || len(regUID) == 0 {
+				klog.V(4).Infof("Failed to get object reference for event.events.k8s.io named \"%s\" in namespace \"%s\"", node.Name, node.Namespace)
+				continue
+			}
+			if ref, ok := globalMap[regUID]; ok {
+				if _, ok := ref.Dependents[evUID]; !ok {
+					ref.Dependents[evUID] = RelationshipSet{}
+				}
+				ref.Dependents[evUID][RelationshipEventRegarding] = struct{}{}
+			}
+			if len(relUID) > 0 {
+				if ref, ok := globalMap[relUID]; ok {
+					if _, ok := ref.Dependents[evUID]; !ok {
+						ref.Dependents[evUID] = RelationshipSet{}
+					}
+					ref.Dependents[evUID][RelationshipEventRelated] = struct{}{}
+				}
+			}
+		default:
+			continue
+		}
+	}
+
 	// Create submap of the root node & its dependents from the global map
 	nodeMap, uidQueue, uidSet := NodeMap{}, []types.UID{}, map[types.UID]struct{}{}
 	if node := globalMap[rootUID]; node != nil {
@@ -117,15 +189,38 @@ func resolveDependents(objects []unstructuredv1.Unstructured, rootUID types.UID)
 		}
 	}
 
-	// Populate remaining data for submap nodes
-	for _, o := range nodeMap {
-		gvk := o.GroupVersionKind()
-		o.Group = gvk.Group
-		o.Kind = gvk.Kind
-		o.Name = o.GetName()
-		o.Namespace = o.GetNamespace()
-	}
-
 	klog.V(4).Infof("Resolved %d dependents for root object (uid: %s)", len(nodeMap)-1, rootUID)
 	return nodeMap
 }
+
+// getEventCoreReferenceUID returns the UID of the object this Event is about.
+// The UID will be an empty string if the reference doesn't exist.
+func getEventCoreReferenceUID(u *unstructuredv1.Unstructured) (types.UID, error) {
+	var regUID types.UID
+	var ev corev1.Event
+	err := runtime.DefaultUnstructuredConverter.FromUnstructured(u.UnstructuredContent(), &ev)
+	if err != nil {
+		return "", err
+	}
+	regUID = ev.InvolvedObject.UID
+
+	return regUID, nil
+}
+
+// getEventReferenceUIDs returns the UID of the object this Event.events.k8s.io
+// is about & the UID of a secondary object if it exist. The UID will be an
+// empty string if the reference doesn't exist.
+func getEventReferenceUIDs(u *unstructuredv1.Unstructured) (types.UID, types.UID, error) {
+	var regUID, relUID types.UID
+	var ev eventsv1.Event
+	err := runtime.DefaultUnstructuredConverter.FromUnstructured(u.UnstructuredContent(), &ev)
+	if err != nil {
+		return "", "", err
+	}
+	regUID = ev.Regarding.UID
+	if ev.Related != nil {
+		relUID = ev.Related.UID
+	}
+
+	return regUID, relUID, nil
+}

pkg/cmd/lineage/printer_table.go

@@ -8,6 +8,7 @@ import (
 
 	appsv1 "k8s.io/api/apps/v1"
 	corev1 "k8s.io/api/core/v1"
+	eventsv1 "k8s.io/api/events/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	unstructuredv1 "k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime"
@@ -141,6 +142,42 @@ func getDeploymentReadyStatus(u *unstructuredv1.Unstructured) (string, string, e
 	return ready, "", nil
 }
 
+// getEventCoreReadyStatus returns the ready & status value of a Event.
+//nolint:unparam
+func getEventCoreReadyStatus(u *unstructuredv1.Unstructured) (string, string, error) {
+	var status string
+	var ev corev1.Event
+	err := runtime.DefaultUnstructuredConverter.FromUnstructured(u.UnstructuredContent(), &ev)
+	if err != nil {
+		return "", "", err
+	}
+	if ev.Count > 1 {
+		status = fmt.Sprintf("%s: %s (x%d)", ev.Reason, ev.Message, ev.Count)
+	} else {
+		status = fmt.Sprintf("%s: %s", ev.Reason, ev.Message)
+	}
+
+	return "", status, nil
+}
+
+// getEventReadyStatus returns the ready & status value of a Event.events.k8s.io.
+//nolint:unparam
+func getEventReadyStatus(u *unstructuredv1.Unstructured) (string, string, error) {
+	var status string
+	var ev eventsv1.Event
+	err := runtime.DefaultUnstructuredConverter.FromUnstructured(u.UnstructuredContent(), &ev)
+	if err != nil {
+		return "", "", err
+	}
+	if ev.DeprecatedCount > 1 {
+		status = fmt.Sprintf("%s: %s (x%d)", ev.Reason, ev.Note, ev.DeprecatedCount)
+	} else {
+		status = fmt.Sprintf("%s: %s", ev.Reason, ev.Note)
+	}
+
+	return "", status, nil
+}
+
 // getPodReadyStatus returns the ready & status value of a Pod which is based
 // off the table cell values computed by printPod from
 // https://github.com/kubernetes/kubernetes/blob/v1.22.1/pkg/printers/internalversion/printers.go.
@@ -275,7 +312,7 @@ func getStatefulSetReadyStatus(u *unstructuredv1.Unstructured) (string, string,
 }
 
 // nodeToTableRow converts the provided node into a table row.
-//nolint:goconst
+//nolint:gocognit,goconst
 func nodeToTableRow(node *Node, rset RelationshipSet, namePrefix string, showGroupFn func(kind string) bool) metav1.TableRow {
 	var name, ready, status, age string
 	var relationships interface{}
@@ -286,6 +323,8 @@ func nodeToTableRow(node *Node, rset RelationshipSet, namePrefix string, showGro
 		name = fmt.Sprintf("%s%s/%s", namePrefix, node.Kind, node.Name)
 	}
 	switch {
+	case node.Group == "" && node.Kind == "Event":
+		ready, status, _ = getEventCoreReadyStatus(node.Unstructured)
 	case node.Group == "" && node.Kind == "Pod":
 		ready, status, _ = getPodReadyStatus(node.Unstructured)
 	case node.Group == "" && node.Kind == "ReplicationController":
@@ -298,6 +337,8 @@ func nodeToTableRow(node *Node, rset RelationshipSet, namePrefix string, showGro
 		ready, status, _ = getReplicaSetReadyStatus(node.Unstructured)
 	case node.Group == "apps" && node.Kind == "StatefulSet":
 		ready, status, _ = getStatefulSetReadyStatus(node.Unstructured)
+	case node.Group == "events.k8s.io" && node.Kind == "Event":
+		ready, status, _ = getEventReadyStatus(node.Unstructured)
 	default:
 		ready, status, _ = getObjectReadyStatus(node.Unstructured)
 	}